tag:theconversation.com,2011:/africa/topics/galaxies-16767/articles
Galaxies – The Conversation
2024-03-26T00:01:06Z
tag:theconversation.com,2011:article/226397
2024-03-26T00:01:06Z
2024-03-26T00:01:06Z
We went looking for glowing interstellar gas – and stumbled on 49 unknown galaxies
<figure><img src="https://images.theconversation.com/files/583996/original/file-20240325-28-68vtd0.jpg?ixlib=rb-1.1.0&rect=350%2C5%2C1514%2C1385&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Gas detected by MeerKAT (white contours) on top of a three-colour optical image from the DECaLS DR10 survey.</span> <span class="attribution"><a class="source" href="https://academic.oup.com/MNRAS/article-lookup/doi/10.1093/mnras/stae684">Glowacki et al. 2024.</a></span></figcaption></figure><p>Stars are born from huge clouds of mostly hydrogen gas floating in space. Astronomers like me study this gas because it helps us understand how stars and galaxies form and grow.</p>
<p>Hydrogen gas gives off a faint glow that is invisible to human eyes but can be observed with a telescope tuned to detect radio waves. </p>
<p>Recently, my colleagues and I were using a telescope like this – a radio telescope called MeerKAT, in South Africa – to look for hydrogen gas in a particular galaxy. We were only observing for less than three hours, which is quite a short amount of time since the hydrogen glow is so faint. </p>
<p>When we looked at the results, we were in for a huge surprise. Instead of discovering hydrogen gas in the galaxy we aimed at, we spotted it in no less than 49 previously unknown galaxies. Our findings are <a href="https://academic.oup.com/MNRAS/article-lookup/doi/10.1093/mnras/stae684">published</a> in the Monthly Notices of the Royal Astronomical Society.</p>
<h2>Gas in galaxies</h2>
<p>The giant clouds of gas in which stars are born are called nebulae. When stars eventually die, they expel their gas into their surrounding environment, where it eventually cools and forms new nebulae. </p>
<p>Galaxies are like huge factories where the life cycle of stars repeats itself over and over. To properly understand galaxies and how they grow and evolve, astronomers need to consider both the stars and the gas making up the galaxy. </p>
<p>One thing we are particularly interested in is “merger events”, when two galaxies collide and merge into a single, larger galaxy. These events can also impact the gas, and kickstart star formation. </p>
<p>Studying gas can often help us understand a galaxy’s history. Gas often extends far further out than the stars in galaxies. </p>
<p>When we see trails of disturbed gas, it is a classic clue that a recent galaxy merger or interaction has occurred. </p>
<p>But we don’t see galactic gas easily with optical telescopes. Thankfully, radio telescopes are a great tool for finding hydrogen gas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of several large white radio dishes standing in a field." src="https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=408&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=408&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583828/original/file-20240323-30-pmfayi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=408&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The MeerKAT radio telescope, made up of 64 radio dishes working together to act as a larger telescope.</span>
<span class="attribution"><span class="source">South African Radio Astronomy Observatory (SARAO)</span></span>
</figcaption>
</figure>
<h2>The MeerKAT radio telescope</h2>
<p>The MeerKAT radio telescope in South Africa <a href="https://www.sarao.ac.za/news/sarao-hosts-meerkat-5-years-conference-in-2024/">recently celebrated its fifth birthday</a>. It is one of the “pathfinder” telescopes for the much larger Square Kilometre Array (SKA), a project under construction in South Africa and Australia. </p>
<p>MeerKAT has already achieved some great results, <a href="https://academic.oup.com/mnras/article/501/3/3833/6034001">from detecting giant radio galaxies</a> to studying the <a href="https://www.sarao.ac.za/media-releases/new-meerkat-radio-image-reveals-complex-heart-of-the-milky-way/">centre of our own galaxy</a>, the Milky Way.</p>
<p>There are large survey projects underway with MeerKAT to study the star-forming hydrogen gas in galaxies. These include the <a href="https://www.aanda.org/articles/aa/full_html/2021/02/aa39655-20/aa39655-20.html">MIGHTEE-HI</a> and <a href="https://science.uct.ac.za/laduma">LADUMA</a> surveys, the latter of which will use MeerKAT for more than 3,000 hours searching one part of the sky for hydrogen gas in very distant galaxies. These surveys are specifically focused on finding hydrogen gas and are carefully planned and carried out with that goal in mind.</p>
<p>But that’s not the only way MeerKAT can be used. Astronomers can also pitch ideas for “open time” observations to tackle other science questions or goals. </p>
<p>That’s how this discovery came about. I was hoping to detect hydrogen gas in one specific galaxy with MeerKAT, as it is the most sensitive telescope for these studies. </p>
<p>We did not find hydrogen gas in that galaxy, which was fine. We astronomers don’t always find what we are looking for.</p>
<p>But when I inspected the MeerKAT data, I spotted some gas located away from the target galaxy. So we investigated further. </p>
<p>By using techniques developed for the larger MeerKAT science surveys such as LADUMA, we found a lot more gas. In total, we had 49 detections.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of a field of stars with small loops of coloured lines." src="https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=587&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=587&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=587&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=738&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=738&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583822/original/file-20240323-16-unrb75.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=738&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The 49 new gas-rich galaxies detected by the MeerKAT radio telescope in South Africa. Each detection is shown as coloured contours, with redder colours indicating more distant gas from us, and bluer colours as closer gas. The background image comes from the optical PanSTARRS survey.</span>
<span class="attribution"><a class="source" href="https://academic.oup.com/MNRAS/article-lookup/doi/10.1093/mnras/stae684">Glowacki et al. 2024</a></span>
</figcaption>
</figure>
<h2>Meet the 49ers</h2>
<p>Each detection of the gas in these galaxies was brand new. In little more than two hours of observing time, MeerKAT had revealed several collections of neighbouring galaxies. </p>
<p>Some of these neighbours are even interacting with each other, as their gas content shows. This was not at all obvious from just looking at the optical images of their stars. </p>
<p>In one case, a galaxy is stealing gas from two companion galaxies, and using it to fuel its own star formation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=549&fit=crop&dpr=1 600w, https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=549&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=549&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=689&fit=crop&dpr=1 754w, https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=689&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/583826/original/file-20240323-16-g8ybij.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=689&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Examples of individual detections of the gas detected by MeerKAT (white contours) on top of a three-colour optical image from the DECaLS DR10 survey. The gas seen here extends further out than the stars in the galaxies.</span>
<span class="attribution"><a class="source" href="https://academic.oup.com/MNRAS/article-lookup/doi/10.1093/mnras/stae684">Glowacki et al. 2024</a></span>
</figcaption>
</figure>
<p>I’ve informally nicknamed this collection of galaxies the 49ers, <a href="https://www.loc.gov/collections/california-first-person-narratives/articles-and-essays/early-california-history/forty-niners/">a reference to the miners of the 1849 California gold rush</a>. </p>
<p>While MeerKAT took the observations containing the 49 gold nuggets in just a couple of hours, winnowing them out required several other tools. These included <a href="https://www.ilifu.ac.za/about/">the ilifu cloud supercomputer</a>, where we reduced the MeerKAT observations (“data reduction” is a kind of pre-processing that makes the raw observations useful) and a data visualisation tool called <a href="https://cartavis.org/">CARTA</a> which we used for the initial discovery of the 49 new galaxies.</p>
<p>We also examined our data with <a href="https://idavie.readthedocs.io/">iDaVIE-v, a virtual reality software for viewing astronomical datasets in 3D</a>. This software has already been <a href="https://theconversation.com/astronomers-have-discovered-a-rare-polar-ring-galaxy-wrapped-in-a-huge-ribbon-of-hydrogen-213254">used for new discoveries such as polar ring galaxies</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/T_AJlFeoRu0?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">VR view of several “49er” gas-rich galaxies.</span></figcaption>
</figure>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/lNuWz_EB9ls?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">VR view of a zoom-in of the 49er galaxies.</span></figcaption>
</figure>
<h2>More gold nuggets to be found</h2>
<p>Finding 49 new galaxies in such a short amount of observation time is quite unusual, even with a telescope as powerful as MeerKAT. However, we know there are more galaxies waiting to be found in upcoming and existing MeerKAT observations. </p>
<p>In some other recent work, our team found traces of gas in more than 80 galaxies (most brand new) across three separate MeerKAT observations. Each of these observations was originally focused on a single galaxy, like the “open time” observation in which we found the 49ers. </p>
<p>What will we find next? We don’t know, but with MeerKAT – and eventually its more powerful successor, the SKA telescope – we’re confident astronomers will turn up plenty more pieces of gold.</p><img src="https://counter.theconversation.com/content/226397/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcin Glowacki does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
An attempt to study gas in one galaxy with the MeerKAT radio telescope detected 49 other galaxies instead.
Marcin Glowacki, Research Associate, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/224564
2024-02-27T16:00:16Z
2024-02-27T16:00:16Z
A black hole discovery could force us to rethink how galaxies came to be
<figure><img src="https://images.theconversation.com/files/578316/original/file-20240227-30-ntlqbc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3834%2C2155&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2021/026/01F8QS893NVRJ6EYF0S46237KP?page=1&Tag=Active%20Galaxies/Quasars">NASA, ESA, Joseph Olmsted (STScI)</a></span></figcaption></figure><p>Peering deep into the infancy of the universe, the European Southern Observatory’s Very Large Telescope (VLT) recently confirmed the discovery of <a href="https://www.nature.com/articles/s41550-024-02195-x">the brightest and fastest growing quasar</a>. Quasars are <a href="https://esahubble.org/wordbank/quasar/">luminous objects in the night sky</a> powered by gas falling into a large black hole at the centre of a galaxy. </p>
<p>The discovery of this record-breaking object was fascinating enough. But another crucial aspect to the announcement is that it raises big questions about galaxy formation in the early universe. In particular, it remains puzzling how this quasar, which existed less than two billion years after the Big Bang, could have grown so large so quickly. Probing this conundrum could even lead to a rethink of how galaxies came to be.</p>
<p>Black holes, the densest objects in the universe, are given this name because their gravitational pull is so incredibly strong that not even light can escape their grasp. How then, can a black hole be the origin of such an intense light source? </p>
<p>Well, in some galaxies, <a href="https://science.nasa.gov/universe/black-holes/">where the black hole is sufficiently large</a>, matter is being drawn in at a ferociously high rate. As it spirals in, violent collisions between gases, dust, and stars result in the emission of huge amounts of light energy. The bigger the black hole, the more violent the collisions and the more light is emitted.</p>
<p>The quasar that was the subject of the latest study, known as J0529-4351, has a mass equivalent to 17 billion suns and is incredibly large. There is a spiralling disk of matter spanning a width of seven light years at the centre of the galaxy and the black hole is growing by accreting (accumulating) this matter. The disk’s width is comparable to the distance between Earth and <a href="https://www.britannica.com/place/Alpha-Centauri">the next nearest star system, Alpha Centauri</a>. </p>
<h2>Hiding in plain sight</h2>
<p>The black hole is growing rapidly by consuming a record-breaking amount of mass, equivalent to one sun each day. This intense accretion of matter releases an amount of radiative energy that’s equivalent to a quadrillion (thousand trillion) suns. </p>
<p>This raises the question of why an object so bright has only just been identified in the night sky, despite decades of astronomical observations. It turns out that this sneaky quasar had been hiding in plain sight.</p>
<p>Despite its astonishing luminosity, J0529-4351 is very distant, meaning that it seamlessly blends in among a sea of dimmer stars that lie much closer to Earth. In fact, this quasar is so far away that the light it emits takes a whopping 12 billion years to reach us here on Earth. </p>
<p>The age of the universe is around 13.7 billion years. So this quasar existed just 1.7 billion years after the <a href="https://science.nasa.gov/universe/the-big-bang/">Big Bang, at the beginning of the Universe</a>. </p>
<p>The universe’s expansion following the Big Bang is what permits us to measure the distance to, and therefore the age of, this quasar. A long-known simple <a href="https://www.bbc.co.uk/bitesize/guides/zphppv4/revision/3">formula called Hubble’s law</a>, states that knowing the velocity that an object is moving away from us allows us to calculate how far away it is.</p>
<figure class="align-center ">
<img alt="Very Large Telescope" src="https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The object was confirmed using the Very Large Telescope facility in Chile.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cerro-paranal-atacama-desert-chile-jan-750390019">Framalicious / Shutterstock</a></span>
</figcaption>
</figure>
<p>The collisions that occur as matter spirals into this quasar’s black hole raise it to scorching temperatures of 10,000°C. Under these conditions, the atoms in the system emit a characteristic spectrum of light. </p>
<p>These discrete frequencies of light form a sort of barcode that astronomers can use to identify the elemental compositions of objects in the night sky. As an object that’s emitting light moves away from us, the frequency of that observed light undergoes a shift, much like how the sound frequency of an ambulance siren shifts depending on whether it is driving towards or away from you. </p>
<p>This shift seen in astronomical objects is <a href="http://csep10.phys.utk.edu/OJTA2dev/ojta/c2c/galaxies/expanding/lookback_tl.html">known as redshift</a>. This, along with Hubble’s Law, has permitted both the age and the distance (both these properties are linked in cosmology) of J0529-4351 to be confirmed.</p>
<p>This bright beacon from the early universe has raised an important question that is baffling astronomers: how could this black hole, in such a relatively short period of time, grow so fast into such a massive object? Under well accepted models of the early universe, it should have taken longer for it to grow to this size. </p>
<p>What’s more, by tuning the artificial intelligence (AI) models used to scan telescope data for these unusual objects, more could still be found in the coming years. If they resemble J0529-4351, physicists would need to seriously rethink their models of the early universe and galaxy formation.</p>
<p>The fastest-growing black hole ever observed will be the perfect target for a system <a href="https://www.mpe.mpg.de/ir/gravityplus">called Gravity+</a>, an upcoming upgrade to an instrument on the Very Large Telescope called an interferometer. This interferometer is an ingenious way of combining data from the four separate telescopes that actually make up the VLT. </p>
<p>Gravity+ is designed to accurately measure the rotational speed and mass of black holes directly, especially those that lie far away from the Earth. </p>
<p>Furthermore, <a href="https://elt.eso.org/">the European Southern Observatory’s’s Extremely Large Telescope</a>, a 39-metre diameter reflecting telescope, is currently under construction in the Chilean Atacama Desert. This is designed for detecting the optical and near-infrared wavelengths characteristic of distant quasars and will make identifying and characterising such elusive objects even more likely in the future.</p><img src="https://counter.theconversation.com/content/224564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Smith does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
The discovery raises big questions about widely accepted models of galaxy formation.
Robin Smith, Senior Lecturer in Physics, Sheffield Hallam University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/218921
2023-12-28T20:38:02Z
2023-12-28T20:38:02Z
Want to get into stargazing? A professional astronomer explains where to start
<p>There are few things more peaceful and relaxing than a night under the stars. Through the holidays, many people head <a href="https://www.lightpollutionmap.info/#zoom=3.80&lat=-28.5041&lon=129.6954&state=eyJiYXNlbWFwIjoiTGF5ZXJCaW5nUm9hZCIsIm92ZXJsYXkiOiJ3YV8yMDE1Iiwib3ZlcmxheWNvbG9yIjpmYWxzZSwib3ZlcmxheW9wYWNpdHkiOjYwLCJmZWF0dXJlc29wYWNpdHkiOjg1fQ==">away from the bright city lights</a> to go camping. They revel in the dark skies, spangled with myriad stars.</p>
<p>As a child, I loved such trips, and they helped cement my passion for the night sky, and for all things space. </p>
<p>One of my great joys as an astronomer is sharing the night sky with people. There is something wondrous about helping people stare at the cosmos through a telescope, getting their first glimpses of the universe’s many wonders. But we can also share and enjoy the night sky just with our own eyes – pointing out the constellations and the planets, or discovering <a href="https://theconversation.com/the-geminids-the-years-best-meteor-shower-is-upon-us-and-this-one-will-be-a-true-spectacle-218923">the joys of watching meteor showers</a>.</p>
<p>It is easy to be bitten by the astronomy bug, and a common question I get asked is “how can I get more into stargazing?”. Here are ways to get started in this fascinating and timeless hobby that won’t break the bank.</p>
<h2>Learning the night sky</h2>
<p>A good place to start if you’re a budding astronomer is to learn your way around the night sky. When I was young, this involved getting hold of a planisphere (a star map, <a href="https://in-the-sky.org/planisphere/index.php">you can make your own here</a>), or a <a href="https://www.amazon.com.au/Turn-Left-Orion-Hundreds-Telescope-ebook/dp/B07H4KN8G2">good reference book</a>. </p>
<p>Today, there are <a href="https://www.space.com/best-stargazing-apps">countless good apps</a> to help you find your way around the night sky. </p>
<p>A great example of such an app is <a href="https://stellarium-web.org/">Stellarium</a> – a planetarium program allowing you to view the night sky from the comfort of your room or to plan an evening’s observing ahead of schedule.</p>
<p>To memorise the night sky, you can try star hopping. Pick out a bright, famous, easy to find constellation, and use it as a guide to help you identify the constellations around it. </p>
<p>Learn one constellation per week, and within a year, you’ll be familiar with most of <a href="https://www.iau.org/public/themes/constellations/">the constellations</a> visible from your location.</p>
<p>Let’s use Orion as an example. The slider below shows images from Stellarium, with Orion riding high in the sky on a summer’s evening. I’ve added arrows to show how you can use Orion (shown in the centre of the map below) to hop around the summer sky.</p>
<p><iframe id="tc-infographic-1007" class="tc-infographic" height="400px" src="https://cdn.theconversation.com/infographics/1007/811d84689c71ac5c004a402a84a7fb446f0ae803/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>To learn the constellations around Orion, your task is relatively straightforward. Head out on a clear, dark summer’s night, and find Orion high to the north. The three stars of Orion’s belt are a fantastic signpost to Orion’s neighbours. </p>
<p>If you follow the line of the belt upwards and to the right, you come to <a href="https://en.wikipedia.org/wiki/Sirius">Sirius</a> – the brightest star in the night sky, and the brightest star in <a href="https://en.wikipedia.org/wiki/Canis_Major">Canis Major</a>, the big hunting dog. Carry the line on and curve to the left as you go, and you’ll find <a href="https://en.wikipedia.org/wiki/Canopus">Canopus</a>, the second brightest star in the sky.</p>
<p>Now come back to Orion’s belt, and follow its line down and to the left. You’ll come to a V-shaped group of stars, including the bright red <a href="https://en.wikipedia.org/wiki/Aldebaran">Aldebaran</a>. This is the <a href="https://en.wikipedia.org/wiki/Hyades_(star_cluster)">Hyades star cluster</a> (with Aldebaran a foreground interloper), which makes up the head of <a href="https://en.wikipedia.org/wiki/Taurus_(constellation)">Taurus</a>, the bull.</p>
<p>Take the line further, and you come to <a href="https://www.space.com/pleiades.html">the Pleiades</a> – often known as the Seven Sisters – a beautiful star cluster easily visible to the naked eye.</p>
<p>Back to Orion again. This time, you’re going to draw a line from <a href="https://en.wikipedia.org/wiki/Rigel">Rigel</a> (the bright star at the top-left of Orion’s boxy body) through <a href="https://en.wikipedia.org/wiki/Betelgeuse">Betelgeuse</a> (the bright red star at the lower-right of the box) and continue it towards the horizon. This takes you to <a href="https://en.wikipedia.org/wiki/Gemini_(constellation)">Gemini</a> – the twins.</p>
<p>Just by using Orion as the signpost, you can find your way to a good number of constellations (the cyan line points to <a href="https://en.wikipedia.org/wiki/Lepus_(constellation)">Lepus</a>, the hare; the white line to <a href="https://en.wikipedia.org/wiki/Canis_Minor">Canis Minor</a>, the little hunting dog). </p>
<p>By star hopping, you’ll slowly but surely learn your way around the night sky until the constellations become familiar friends.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/kindred-skies-ancient-greeks-and-aboriginal-australians-saw-constellations-in-common-74850">Kindred skies: ancient Greeks and Aboriginal Australians saw constellations in common</a>
</strong>
</em>
</p>
<hr>
<h2>Virtual observing</h2>
<p>Looking at the sky with the naked eye is a wonderful thing, but it’s also great to zoom in and see more detail.</p>
<p>What if you don’t have access to binoculars or a telescope of your own? Thankfully, software like Stellarium can give you a fantastic virtual observing experience.</p>
<p>Imagine you want to see Saturn’s rings – a spectacular sight through even a small telescope. You can easily do this with Stellarium. Find Saturn by using the search bar and click on it to bring up the planet’s info. </p>
<p>Click on the cross-hair symbol to “lock on”, then zoom in. The further you zoom in, the more you’ll see. You can even run the clock forwards or backwards to see the planet’s moons move in their orbits, or the tilt of Saturn’s rings <a href="https://theconversation.com/will-saturns-rings-really-disappear-by-2025-an-astronomer-explains-217370">changing from our viewpoint over time</a>.</p>
<p>A virtual observing session is as simple as that – just pan around the sky until you find something you want to see, and zoom in.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close up of rotating Saturn" src="https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564091/original/file-20231207-17-qvar43.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Example of using the clock feature in Stellarium to see the movement of Saturn’s moons.</span>
<span class="attribution"><span class="source">Stellarium</span></span>
</figcaption>
</figure>
<h2>A hobby best shared</h2>
<p>Now, a virtual observing session is great, but it pales compared to the real thing. I’d recommend using planetarium programs like Stellarium to figure out what you want to see, then heading out to look at it with your own eyes.</p>
<p>Astronomy is a wonderful hobby, and one that is best shared. Most towns and cities have their own astronomy clubs, and they’re usually more than happy to welcome guests who want to gaze at the night sky. </p>
<p>I joined my local astronomy society, the <a href="https://www.wyas.org.uk/">West Yorkshire Astronomical Society</a> in the United Kingdom, when I was just eight years old. I owe them so much. The members were incredibly supportive of a young kid with so many questions, and I genuinely believe I would not be where I am today without their help. As a member, I saw firsthand just how fantastic the amateur astronomy community is. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A telescope inside a dome during daytime, with a young teen and two older men standing next to it" src="https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=438&fit=crop&dpr=1 600w, https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=438&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=438&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=550&fit=crop&dpr=1 754w, https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=550&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/562685/original/file-20231130-29-ogkxpc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=550&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The author Jonti Horner at age 16, showing then Astronomer Royal of the UK, Arnold Wolfendale (right), the WYAS 18-inch telescope, hand-made by members. Also seen is the society’s then president, Ken Willoughby.</span>
<span class="attribution"><span class="source">Alan Horner, author provided</span></span>
</figcaption>
</figure>
<p>At the society, we had weekly talks on astronomy, given by the club members and visiting astronomers from local universities. We also had regular night sky viewing nights, using the society’s very own telescope – a behemoth the members had built themselves. </p>
<p>People who are passionate about their hobby love nothing more than sharing it with others. The members of astronomical societies are fantastic guides to the night sky, and they often have incredible equipment they’re more than happy to share with you.</p>
<p>Both astronomy clubs and universities often offer public night sky viewing nights, which are the perfect opportunity to peer at the sky through a telescope, with an experienced guide on hand to find the most impressive sights to share. </p>
<p>So, if you want to learn more about the night sky, reach out to your local astronomy society – it could be the start of something very special.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/want-to-buy-a-home-telescope-tips-from-a-professional-astronomer-to-help-you-choose-218604">Want to buy a home telescope? Tips from a professional astronomer to help you choose</a>
</strong>
</em>
</p>
<hr>
<p><em>If you want to find a local astronomy group, check out <a href="https://astronomy.org.au/amateur/amateur-societies/australia/">this list</a>. If you’re a member of a group that isn’t listed, please reach out to get them to update the list using the ‘Contact Us’ link.</em></p><img src="https://counter.theconversation.com/content/218921/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonti Horner does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
People have been looking up at the stars for thousands of years. Here’s where to start if you want to learn more about the night sky – from spotting easy-to-find constellations to using the best apps.
Jonti Horner, Professor (Astrophysics), University of Southern Queensland
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/219205
2023-12-06T00:53:30Z
2023-12-06T00:53:30Z
Astronomers finally caught radio waves from 40 large galaxies in the nearby universe
<figure><img src="https://images.theconversation.com/files/563537/original/file-20231205-21-lmh6mq.jpg?ixlib=rb-1.1.0&rect=14%2C0%2C3196%2C2153&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Australian Square Kilometre Array Pathfinder in the Western Australian desert.</span> <span class="attribution"><a class="source" href="https://www.atnf.csiro.au/projects/askap/gallery.html">CSIRO</a></span></figcaption></figure><p>Supermassive black holes reside in some of the biggest galaxies in the universe. They tend to be billions of times more massive that our Sun, and not even light itself can escape a black hole once it gets too close.</p>
<p>But it’s not all darkness. Supermassive black holes power some of the most luminous celestial objects in the universe – active galactic nuclei, which shine across the spectrum of light, including radio waves. </p>
<p>The active galactic nucleus in nearby galaxy Messier 87 is a prodigious emitter of radio waves, 27 orders of magnitude more powerful than the <a href="https://en.wikipedia.org/wiki/Eglin_AFB_Site_C-6">most powerful radio transmitters on Earth</a>.</p>
<p>But not all galaxies blast radio waves like Messier 87. Some very massive nearby galaxies have gone undetected in the radio spectrum despite containing supermassive black holes. Are they switched on in the radio at all, or are they – and therefore their black holes – totally silent?</p>
<p>To find out, we searched for radio waves from the most massive galaxies in the nearby universe, with our results now accepted for publication <a href="https://ui.adsabs.harvard.edu/abs/2023arXiv231115456B/abstract">in the Publications of the Astronomical Society of Australia</a>.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A red and orange donut shape on a black background" src="https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=532&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=532&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=532&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=668&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=668&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563524/original/file-20231205-15-zu7j1t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=668&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The black hole in Messier 87 is the engine for a powerful radio source.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/black-hole-image-makes-history">Event Horizon Telescope Collaboration</a></span>
</figcaption>
</figure>
<h2>A big engine</h2>
<p>It may seem odd that black holes can power anything. After all, no matter – not even light – can escape a black hole. But a lot can happen before the point of no return, known as the event horizon.</p>
<p>As matter falls towards the black hole, it picks up tremendous speed. Particles can end up travelling close to the speed of light, and when particles smash at that speed, they can release a staggering amount of energy. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-do-black-holes-pull-in-light-208848">Curious Kids: how do black holes pull in light?</a>
</strong>
</em>
</p>
<hr>
<p>Several percent of the mass that falls towards a black
hole – “feeds” it – can get <a href="https://ui.adsabs.harvard.edu/abs/2017ApJ...836L...1T/abstract">released as light</a>. Feed a black hole, and it can be a big engine that blasts out radio waves. </p>
<p>So, supermassive black holes are in all the biggest galaxies, but are they always being fed? That question motivated our study. To listen for radio waves from these enormous objects, we used the ASKAP radio telescope in Western Australia, owned and operated by CSIRO – Australia’s national science agency.</p>
<h2>Tuning in on the radio</h2>
<p>Way back in the 1940s, astronomers started detecting radio waves from some massive galaxies using the first radio telescopes. This includes galaxies familiar to amateur astronomers, including Messier 87 in the Virgo constellation and NGC 5128 in Centaurus. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Black and white image of silhouettes of two people standing on a clifftop next to an antenna" src="https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563531/original/file-20231205-29-9eemqo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Very powerful celestial sources of radio waves were detected back in the 1940s, thanks to radio telescopes like this one at Dover Heights, Sydney.</span>
<span class="attribution"><span class="source">CSIRO Radio Astronomy Image Archive</span></span>
</figcaption>
</figure>
<p>As technology advanced, more very massive galaxies were detected in radio waves. In the early 2000s, astronomers found that about <a href="https://doi.org/10.1111/j.1365-2966.2007.11937.x">a third of very massive galaxies</a> in the Sloan Digital Sky Survey were detectable in the radio data from the Very Large Array, located in New Mexico. </p>
<p>A decade ago, <a href="https://ui.adsabs.harvard.edu/abs/2011ApJ...731L..41B/abstract">our team also used data</a> from the Very Large Array to search for radio emissions from the most massive nearby galaxies. Some were easily detected while others were indistinguishable from noise. </p>
<p>However, there was a strong hint. While the radio signals from the most massive galaxies were sometimes not distinguishable from noise individually, we always found a positive signal. </p>
<p>If some galaxies were not emitting radio waves, we would expect random noise to produce a mix of positive and negative signals. Getting a positive signal every time suggested all massive galaxies are radio sources. But digging into the noise left us unsure, until now.</p>
<h2>New telescopes and a new view</h2>
<p>There have been major advances in radio telescopes during the past decade, both in radio receivers and computing power. New radio telescopes include the ASKAP radio telescope and the Murchison Widefield Array, both located at Inyarrimanha Ilgari Bundara, CSIRO’s Murchison Radio-astronomy Observatory on Wajarri Yamaji country in Western Australia. There is also the <a href="https://www.astron.nl/telescopes/lofar/">Low Frequency Array</a> (Lofar) in Europe.</p>
<p>These telescopes can survey the sky with greater sensitivity and speed than the previous generation of radio telescopes. For example, <a href="https://research.csiro.au/racs/home/survey/">the Rapid ASKAP Continuum Survey</a> is just a preliminary radio survey of 83% of the entire sky, but is already three times more sensitive than comparable surveys with the previous generation of radio telescopes.</p>
<p>For our new study, we no longer needed to look for mere hints of the noise. We detected radio waves from all 40 of the most massive galaxies in our survey area.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-found-some-strange-radio-sources-in-a-distant-galaxy-cluster-theyre-making-us-rethink-what-we-thought-we-knew-187631">We found some strange radio sources in a distant galaxy cluster. They're making us rethink what we thought we knew.</a>
</strong>
</em>
</p>
<hr>
<h2>Dialled up and down</h2>
<p>So, it now looks like all very massive galaxies are emitting radio waves, but are all of their black holes being fed? Most are, but probably not all.</p>
<p><a href="https://ui.adsabs.harvard.edu/abs/2022A%26A...660A..93C/abstract">Studies with Lofar</a> suggest some radio sources in massive galaxies are afterglows from earlier activity. It is likely these are temporary pauses, and these black holes will fire up again. </p>
<p>Another piece of the puzzle is the radio power. Two galaxies of the same mass can differ in radio power by a factor of 10,000. Why does this happen?</p>
<p>We don’t know the answer yet, but there are some clues. Our work and <a href="https://ui.adsabs.harvard.edu/abs/2023A%26A...673A..12Z/abstract">a recent study with Lofar</a> find that, on average, the galaxies that rotate the least are the strongest radio wave emitters. Some of the exceptions to this trend are curious, with evidence of mergers with other galaxies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A star field with several galaxies of different shapes visible in the centre" src="https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=445&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=445&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=445&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=559&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=559&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563526/original/file-20231205-19-f7uav3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=559&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Galaxy NGC 6876 emits radio waves, but is thousands of times fainter than Messier 87.</span>
<span class="attribution"><span class="source">Legacy Imaging Surveys/D. Lang (Perimeter Institute)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>There is much to learn about very massive galaxies and their black holes, but data from the new generation of radio telescopes has revealed a great deal. </p>
<p>All very massive galaxies emit radio waves, but their power varies. Determining how all this works will be a challenge, but there are clues for astronomers to now follow.</p><img src="https://counter.theconversation.com/content/219205/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael J. I. Brown receives research funding from the Australian Research Council and Monash University.</span></em></p>
Do all big black holes in very massive galaxies emit radio waves? We used the latest radio telescopes to find out.
Michael J. I. Brown, Associate Professor in Astronomy, Monash University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/213254
2023-09-13T00:11:58Z
2023-09-13T00:11:58Z
Astronomers have discovered a rare ‘polar ring galaxy’ wrapped in a huge ribbon of hydrogen
<figure><img src="https://images.theconversation.com/files/547443/original/file-20230911-27-pc043c.jpg?ixlib=rb-1.1.0&rect=9%2C2%2C1588%2C831&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jayanne English (U. Manitoba) / N. Deg (Queen’s U.) / The WALLABY team / CSIRO / ASKAP / NAOJ / Subaru Telescope</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Galaxies come in many shapes and sizes, from giant, slowly rotating ovals and fast-whirling spiral disks to faint ball-shaped blobs and dwarf irregulars. Most large, bright galaxies – including our own Milky Way – are orbited by a gang of much smaller dwarf galaxies.</p>
<p>Most of this we know from optical images, whether taken with small backyard telescopes or much bigger dedicated ground- and space-based telescopes that reveal the light from billions of distant suns. However, as we are discovering, what happens beyond the bright disk of stars may be even more interesting.</p>
<p>With radio telescopes, we can map the distinctive glow of free-floating hydrogen atoms throughout the universe, whether they are inside galaxies, around them, or lurking in the lonely spaces between. </p>
<p>Using CSIRO’s <a href="https://www.atnf.csiro.au/projects/askap/">Australian Square Kilometre Array Pathfinder (ASKAP)</a> radio telescope, on Wajarri Yamaji Country in Western Australia, we recently discovered an enormous ribbon of hydrogen encircling a spiral galaxy called NGC 4632. The results are described in <a href="https://academic.oup.com/mnras/article-lookup/doi/10.1093/mnras/stad2312">a new paper</a> in Monthly Notices of the Royal Astronomical Society. </p>
<h2>Galactic leftovers</h2>
<p>NGC 4632 appears to be a very rare formation called a “polar ring galaxy”, as the hydrogen ring seems to be rotating over the poles of the galaxy’s disk. The gas in the ring, which makes up about half of the system’s mass, was likely hoovered up from a companion galaxy. </p>
<p>In the words of my colleague <a href="https://nathandeg.com/">Nathan Deg</a> at Queen’s University in Canada, who led the new study:</p>
<blockquote>
<p>Polar ring galaxies are some of the most spectacular looking galaxies that we can see. Beyond just being beautiful, they provide important clues about the formation and growth of galaxies over time. </p>
</blockquote>
<p>The location and movement of these polar rings can also tell us about the shape of the halo of invisible dark matter astronomers believe surrounds most galaxies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=261&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=261&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=261&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=328&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=328&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547710/original/file-20230912-23-aleskq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=328&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Left: the hydrogen ring discovered by ASKAP around the spiral galaxy NGC 4632, after removing the bright hydrogen emission detected in the galaxy’s disk. Middle: An optical image of the stellar disk from the Subaru telescope. Right: Composite image showing the stellar disk of NGC 4632 surrounded by the large hydrogen ring.</span>
<span class="attribution"><span class="source">Deg et al. 2023, MNRAS / Jayanne English / Tom Jarrett / Nathan Deg / Wallaby collaborators / CSIRO / ASKAP / NAOJ / Subaru Telescope.</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Spiral galaxies like NGC 4632 are typically rich in cold hydrogen gas. The gas provides the fuel for star formation and typically extends well beyond the bright disk of stars. </p>
<p>In the outskirts of spiral galaxies, we often see that the shape of the gas disk is warped. Why does this happen?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/experts-solve-the-mystery-of-a-giant-x-shaped-galaxy-with-a-monster-black-hole-as-its-engine-138205">Experts solve the mystery of a giant X-shaped galaxy, with a monster black hole as its engine</a>
</strong>
</em>
</p>
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<p>Some warps may be caused by a galaxy wrestling with its neighbours via gravity, stealing gas which collects in the galaxy’s outer disk or forms a polar ring. This is quite a common process by which galaxies grow: our Milky Way galaxy is known to have <a href="https://www.science.org/content/article/milky-way-messy-eater-map-shows-crumbs-it-has-left-behind">munched up</a> several small companions.</p>
<h2>Hunting hydrogen</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of the front cover of The Astronomical Journal showing a green and blue image of a galaxy." src="https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=782&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=782&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=782&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=983&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=983&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547694/original/file-20230912-17-izc514.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=983&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bärbel Koribalski and Magda Arnaboldi’s early results on hydrogen around the polar ring galaxy NGC 4650A made it to the front cover of The Astronomical Journal in 1997.</span>
<span class="attribution"><span class="source">The Astronomical Journal</span></span>
</figcaption>
</figure>
<p>I was first inspired to study polar ring galaxies in the 1990s by astronomers <a href="https://iceds.anu.edu.au/people/academics/prof-penny-sackett">Penny Sackett</a> and <a href="https://science.nasa.gov/astrophysics/organization-and-staff/staff-bios/dr-linda-sparke">Linda Sparke</a>. Eager to understand what these strange cosmic structures could reveal about dark matter, I teamed up with Magda Arnaboldi to observe <a href="https://articles.adsabs.harvard.edu/pdf/1997AJ....113..585A">hydrogen in the nearby galaxy NGC 4650A</a> using CSIRO’s <a href="https://www.narrabri.atnf.csiro.au/">Australia Telescope Compact Array (ATCA)</a> on Gomeroi Country, outside Narrabri in north-west New South Wales.</p>
<p>Two big projects, the <a href="https://www.atnf.csiro.au/research/multibeam/">HI Parkes All Sky Survey (HIPASS)</a> and the <a href="https://www.atnf.csiro.au/research/LVHIS/">Local Volume HI Survey (LVHIS)</a>, set the scene for much of my current research on galaxies. As plans advanced for the much larger and more powerful ASKAP telescope, I was one of the founders of the <a href="https://rdcu.be/b5Bfg">Wallaby project</a>, which uses ASKAP’s capabilities to conduct a <a href="https://wallaby-survey.org">huge survey</a> of hydrogen in the local universe.</p>
<figure class="align-right ">
<img alt="A photo of a woman standing on red soil with a large radio telescope in the background." src="https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547672/original/file-20230912-21-8ycush.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Bärbel Koribalski’s first visit to the ASKAP site in Western Australia. One of ASKAP’s 36 dishes dotted over a 6-km diameter area is seen in the background.</span>
<span class="attribution"><span class="source">Cornelia Brem</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>ASKAP began full operations in late 2022. The telescope is located at <a href="https://research.csiro.au/mro/inyarrimanha-ilgari-bundara/">Inyarrimanha Ilgari Bundara</a>, CSIRO’s Murchison radio astronomy observatory: the traditional name means ‘sharing sky and stars’ in the Wajarri language.</p>
<p>ASKAP now produces such vast amounts of data that we need dedicated software running on the <a href="https://pawsey.org.au/systems/setonix/">Setonix supercomputer</a> in Perth, not only to produce wide-field images and cubes, but also to sift through them for signs of hydrogen in distant galaxies. We can then conduct more detailed studies of the most interesting galaxies. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wtf-newly-discovered-ghostly-circles-in-the-sky-cant-be-explained-by-current-theories-and-astronomers-are-excited-142812">'WTF?': newly discovered ghostly circles in the sky can't be explained by current theories, and astronomers are excited</a>
</strong>
</em>
</p>
<hr>
<h2>Visualising galaxies</h2>
<p>Our latest paper highlights two galaxies (of 600 found in our first pilot study) that contain unusual structures. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A screenshot of a data cube showing the hydrogen gas in and around the galaxy NGC 4632." src="https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=542&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=542&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=542&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=681&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=681&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547671/original/file-20230912-31-s73lh2.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=681&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 3D visualisation of the Wallaby data cube around NGC 4632, created with the iDaVIE virtual reality software.</span>
<span class="attribution"><span class="source">Deg et al. / iDaVIE</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>As Deg puts it, “finding two potential polar ring galaxies in the Wallaby pilot survey is incredibly exciting, as it suggests that these objects may be more common than previously thought”.</p>
<p>To explore the shapes of galaxies we often use <a href="https://wwwmpa.mpa-garching.mpg.de/galform/data_vis/">3D visualisation</a> – and even virtual reality software such as <a href="https://www.sciencedirect.com/science/article/pii/S2213133721000561">iDaVIE</a>.</p>
<p>We expect the full Wallaby survey will reveal more than 200,000 hydrogen-rich galaxies. Among them will be many more unusual objects like the polar ring around NGC 4632, which can then be used to learn more about dark matter. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/dkMr-D2719w?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure><img src="https://counter.theconversation.com/content/213254/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Baerbel Koribalski is affiliated with the School of Science at Western Sydney University.</span></em></p>
New ASKAP images reveal a giant hydrogen ring around the spiral galaxy NGC 4632.
Baerbel Koribalski, Senior research scientist, CSIRO
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/207602
2023-08-08T12:29:39Z
2023-08-08T12:29:39Z
Looking back toward cosmic dawn − astronomers confirm the faintest galaxy ever seen
<figure><img src="https://images.theconversation.com/files/540179/original/file-20230731-16129-x8ubg4.jpg?ixlib=rb-1.1.0&rect=10%2C12%2C1012%2C1019&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A phenomenon called gravitational lensing can help astronomers observe faint, hard-to-see galaxies. </span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/chandra/images/abell-2744.html">NASA/STScI</a></span></figcaption></figure><p>The universe we live in is a transparent one, where light from stars and galaxies shines bright against a clear, dark backdrop. But this wasn’t always the case – in its early years, the universe was filled with a fog of hydrogen atoms that obscured light from the earliest stars and galaxies. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Clouds interrupted by bright spots" src="https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=477&fit=crop&dpr=1 600w, https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=477&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=477&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=599&fit=crop&dpr=1 754w, https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=599&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/541497/original/file-20230807-25-kgcqd9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=599&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The early universe was filled with a fog made up of hydrogen atoms until the first stars and galaxies burned it away.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/spitzer/multimedia/firststars-blue-20061218.html">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The intense ultraviolet light from the first generations of stars and galaxies is thought to have burned through the hydrogen fog, transforming the universe into what we see today. While previous generations of telescopes lacked the ability to study those early cosmic objects, astronomers are now using the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a>’s superior technology to study the stars and galaxies that formed in the immediate aftermath of the Big Bang.</p>
<p>I’m an <a href="https://www.robertsborsani.com/">astronomer who studies the farthest galaxies</a> in the universe using the world’s foremost ground- and space-based telescopes. Using new observations from the Webb telescope and a phenomenon called gravitational lensing, my team <a href="https://doi.org/10.1038/s41586-023-05994-w">confirmed the existence</a> of the faintest galaxy currently known in the early universe. The galaxy, called JD1, is seen as it was when the universe was only 480 million years old, or 4% of its present age.</p>
<h2>A brief history of the early universe</h2>
<p>The first billion years of the universe’s life were a <a href="https://doi.org/10.1038/nature09527">crucial period in its evolution</a>. In the first moments after the Big Bang, matter and light were bound to each other in a hot, dense “soup” of <a href="https://theconversation.com/explainer-what-are-fundamental-particles-38339">fundamental particles</a>.</p>
<p>However, a fraction of a second after the Big Bang, the universe <a href="https://doi.org/10.1051/0004-6361/201833887">expanded extremely rapidly</a>. This expansion eventually allowed the universe to cool enough for light and matter to separate out of their “soup” and – some 380,000 years later – form hydrogen atoms. The hydrogen atoms appeared as an intergalactic fog, and with no light from stars and galaxies, the universe was dark. This period is known as the <a href="https://doi.org/10.1126/science.1085325">cosmic dark ages</a>.</p>
<p>The arrival of the first generations of stars and galaxies several hundred million years after the Big Bang bathed the universe in extremely hot UV light, which <a href="https://www.youtube.com/watch?v=dgXfTx2e2MA&ab_channel=djxatlanta">burned – or ionized – the hydrogen fog</a>. <a href="https://theconversation.com/after-our-universes-cosmic-dawn-what-happened-to-all-its-original-hydrogen-65527">This process</a> yielded the transparent, complex and beautiful universe we see today.</p>
<p>Astronomers like me call the first billion years of the universe – when this hydrogen fog was burning away – the <a href="https://doi.org/10.1038/nature09527">epoch of reionization</a>. To fully understand this time period, we study when the first stars and galaxies formed, what their main properties were and whether they were able to produce enough UV light to burn through all the hydrogen.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/dgXfTx2e2MA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A visual model showing the burning of hydrogen fog by UV light in the ‘reionization’ era. Ionized, or burned, regions are blue and translucent. Ionization fronts are red and white, and neutral regions are dark and opaque. Via djxatlanta on Youtube.</span></figcaption>
</figure>
<h2>The search for faint galaxies in the early universe</h2>
<p>The first step toward understanding the epoch of reionization is finding and confirming the distances to galaxies that astronomers think might be responsible for this process. Since light travels at a finite speed, it takes time to arrive to our telescopes, so astronomers <a href="https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603">see objects as they were in the past</a>.</p>
<p>For example, light from the center of our galaxy, the Milky Way, takes about 27,000 years to reach us on Earth, so we see it as it was 27,000 years in the past. That means that if we want to see back to the very first instants after the Big Bang (the universe is 13.8 billion years old), we have to look for objects at extreme distances.</p>
<p>Because galaxies residing in this time period are so far away, they appear extremely <a href="https://doi.org/10.1038/s41586-023-05994-w">faint and small</a> to our telescopes and emit most of their light in the infrared. This means astronomers need powerful infrared telescopes like Webb to find them. Prior to Webb, virtually all of the distant galaxies found by astronomers were exceptionally bright and large, simply because our telescopes weren’t sensitive enough to see the fainter, smaller galaxies. </p>
<p>However, it’s the latter population that are far more numerous, representative and likely to be the main drivers to the reionization process, not the bright ones. So, these faint galaxies are the ones astronomers need to study in greater detail. It’s like trying to understand the evolution of humans by studying entire populations rather than a few very tall people. By allowing us to see faint galaxies, Webb is opening a new window into studying the early universe.</p>
<h2>A typical early galaxy</h2>
<p>JD1 is one such “typical” faint galaxy. It was <a href="https://doi.org/10.1088/2041-8205/793/1/L12">discovered in 2014 with the Hubble Space Telescope</a> as a suspect distant galaxy. But Hubble didn’t have the capabilities or sensitivity to confirm its distance – it could make only an educated guess.</p>
<p>Small and faint nearby <a href="https://doi.org/10.48550/arXiv.2303.15431">galaxies can sometimes be mistaken as distant ones</a>, so astronomers need to be sure of their distances before we can make claims about their properties. Distant galaxies therefore remain “candidates” until they are confirmed. The Webb telescope finally has the capabilities to confirm these, and JD1 was one of the first major confirmations by Webb of an extremely distant galaxy candidate found by Hubble. This confirmation ranks it as <a href="https://doi.org/10.1038/s41586-023-05994-w">the faintest galaxy yet seen in the early universe</a>.</p>
<p>To confirm JD1, an international team of astronomers and I used Webb’s near-infrared spectrograph, <a href="https://jwst.nasa.gov/content/observatory/instruments/nirspec.html">NIRSpec</a>, to obtain an infrared spectrum of the galaxy. The spectrum allowed us to pinpoint the distance from Earth and determine its age, the number of young stars it formed and the amount of dust and heavy elements that it produced.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bright lights (galaxies and a few stars) against a dark backdrop of sky. One faint galaxy is shown in a magnified box as a dim smudge." src="https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536357/original/file-20230707-23-dlm4qh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A sky full of galaxies and a few stars. JD1, pictured in a zoomed-in box, is the faintest galaxy yet found in the early universe.</span>
<span class="attribution"><span class="source">Guido Roberts-Borsani/UCLA; original images: NASA, ESA, CSA, Swinburne University of Technology, University of Pittsburgh, STScI</span></span>
</figcaption>
</figure>
<h2>Gravitational lensing, nature’s magnifying glass</h2>
<p>Even for Webb, JD1 would be impossible to see without a helping hand from nature. JD1 is located behind a large cluster of nearby galaxies, called <a href="https://webbtelescope.org/contents/media/images/2019/20/4376-Image">Abell 2744</a>, whose combined gravitational strength bends and amplifies the light from JD1. This effect, known as gravitational lensing, makes JD1 appear larger and 13 times brighter than it ordinarily would. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Rsx0AGQhQvs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Large galaxies can warp and distort light traveling around them. This video shows how this process, called gravitational lensing, works.</span></figcaption>
</figure>
<p>Without gravitational lensing, astronomers would not have seen JD1, even with Webb. The combination of JD1’s gravitational magnification and new images from another one of Webb’s near-infrared instruments, <a href="https://webb.nasa.gov/content/observatory/instruments/nircam.html">NIRCam</a>, made it possible for our team to study the galaxy’s structure in unprecedented detail and resolution. </p>
<p>Not only does this mean we as astronomers can study the inner regions of early galaxies, it also means we can start determining whether such early galaxies were small, compact and isolated sources, or if they were merging and interacting with nearby galaxies. By studying these galaxies, we are tracing back to the building blocks that shaped the universe and gave rise to our cosmic home.</p><img src="https://counter.theconversation.com/content/207602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with program JWST-ERS-1324, and the authors acknowledge financial support from NASA through grant JWST-ERS-1324.</span></em></p>
The universe used to be filled with a hydrogen fog, before early stars and galaxies burned through the haze. Astronomers are studying galaxies that tell them about this period in the early universe.
Guido Roberts-Borsani, Postdoctoral Researcher in Astrophysics, University of California, Los Angeles
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/203557
2023-05-24T21:06:10Z
2023-05-24T21:06:10Z
Astronomers detected two major targets with a single telescope – a mysterious signal and its source galaxy
<figure><img src="https://images.theconversation.com/files/521206/original/file-20230417-28-c0lcs2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">ASKAP multiple landscape backview.</span> <span class="attribution"><span class="source">CSIRO</span></span></figcaption></figure><p>Astronomers have been working to better understand the galactic environments of fast radio bursts (FRBs) – intense, momentary bursts of energy occurring in mere milliseconds and with unknown cosmic origins.</p>
<p>Now, a study of the slow-moving, star-forming gas in the same galaxy found to host an FRB <a href="https://doi.org/10.3847/1538-4357/acc1e3">has been published in The Astrophysical Journal</a>. This is only the fourth-ever publication on two completely different areas of astronomy describing the same galaxy. </p>
<p>Even more remarkable is the fact that a single telescope made the discovery possible – from the same observation. </p>
<h2>Fast radio mysteries</h2>
<p>FRBs, first detected in 2007, are incredibly powerful pulses of radio waves. They originate from distant galaxies, and the signal typically only lasts a few milliseconds.</p>
<p>FRBs are immensely useful for studying the cosmos, from investigating <a href="https://news.ucsc.edu/2020/05/missing-matter.html">the matter that makes up the universe</a>, to even using them <a href="https://academic.oup.com/mnras/article-abstract/516/4/4862/6694260">to constrain the Hubble constant</a> – the measure of how much the universe is expanding.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-brief-history-what-we-know-so-far-about-fast-radio-bursts-across-the-universe-154381">A brief history: what we know so far about fast radio bursts across the universe</a>
</strong>
</em>
</p>
<hr>
<p>However, the origin of FRBs is an ongoing puzzle for astronomers. Some FRBs are known to repeat, <a href="https://iopscience.iop.org/article/10.1088/1674-1056/aca7ed">sometimes over a thousand times</a>. Others have only been detected once.</p>
<p>Whether these repeating or non-repeating signals have formed differently <a href="https://academic.oup.com/mnras/article-abstract/500/3/3275/5944128">is currently being investigated by several research groups</a>. At one point, we had more theories on how fast radio bursts are made than detections of them.</p>
<p>It’s an exciting time to be studying FRBs, as showcased by the recent study <a href="https://theconversation.com/for-the-first-time-astronomers-have-linked-a-mysterious-fast-radio-burst-with-gravitational-waves-202341">associating an FRB with a gravitational wave</a>. If that finding holds true, it means at least some FRBs could be created by two neutron stars merging to form a black hole. </p>
<p>However, it is hard to pinpoint where exactly fast radio bursts come from. They are extremely bright yet so brief, getting an accurate position is hard for many radio telescopes. Without knowing where precisely these bursts originate, we cannot study the galaxies they are found in. And without knowing the environments FRBs are formed in, we cannot fully solve their mysteries. </p>
<p>One telescope in Australia is now helping us figure it out. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&rect=0%2C232%2C5725%2C3181&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521203/original/file-20230417-1956-ensh6k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some of the ASKAP dishes.</span>
<span class="attribution"><span class="source">CSIRO (Author provided)</span></span>
</figcaption>
</figure>
<h2>The tool for the job</h2>
<p><a href="https://www.csiro.au/askap">CSIRO’s ASKAP radio telescope</a> (Australian Square Kilometre Array Pathfinder), located in the Western Australian desert, is a remarkable instrument. Made up of an array of 36 dishes separated by up to six kilometres, ASKAP can detect FRBs and <a href="https://astronomy.curtin.edu.au/research/craft/">pinpoint them to their host galaxies</a>. </p>
<p>ASKAP can in fact perform its FRB search at the same time as observations for other science surveys. <a href="https://wallaby-survey.org/">One such ASKAP survey</a> will map the star-forming gas in galaxies across the Southern sky, helping us understand how galaxies evolve. </p>
<p>During a recent observation for this survey, ASKAP also detected a new FRB, and we were able to identify the galaxy it comes from – a nearby <a href="https://astronomy.swin.edu.au/cosmos/S/spiral+galaxy">spiral galaxy</a> much like our own Milky Way. </p>
<h2>A gas-filled galaxy</h2>
<p>ASKAP was able to find the cold neutral hydrogen gas – the source of star formation – in this spiral galaxy. As far as FRB host galaxies go, this is already a rare detection of this gas; only three other cases have been published so far. These <a href="https://iopscience.iop.org/article/10.3847/2041-8213/ac4ca8">had required follow-up observations</a>, or <a href="https://iopscience.iop.org/article/10.3847/2041-8213/ac2b35">relied on other older observations</a>, made with different telescopes.</p>
<p>Here, ASKAP gave us both the FRB and the gas surrounding it. It is the first simultaneous detection of these rarely overlapping occurrences.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=495&fit=crop&dpr=1 600w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=495&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=495&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=622&fit=crop&dpr=1 754w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=622&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/521001/original/file-20230414-20-jqg7qh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=622&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">ASKAP both found the cold hydrogen gas (white contours) in this spiral galaxy, and pinpointed an FRB near the centre (location given by the red ellipse). Glowacki et al. 2023; ESO and ASKAP.</span>
</figcaption>
</figure>
<p>Disturbed gas which ASKAP can detect can give us an indication that a galaxy merger recently happened, which tells us about the star forming history of the galaxy. In turn this gives us clues as to what may cause FRBs. </p>
<p>The previous studies of the gas surrounding FRBs found fast radio bursts reside in very dynamic systems, suggesting tumultuous galaxy mergers triggered the bursts.</p>
<p>For this particular FRB, however, the host galaxy environment is surprisingly calmer. Further studies will be needed to find out if overall we see disturbed gas environments for FRBs, or if there are distinct scenarios – and potentially multiple creation paths – for FRBs.</p>
<h2>More to come</h2>
<p>Given the uniqueness of such dual detections, this result showcases the strength and versatility of ASKAP. This is the first simultaneous detection of both an FRB and the gas in its host galaxy. </p>
<p>And this is just the start. ASKAP is set to detect and localise <a href="https://www.atnf.csiro.au/research/interferometry/public/How_CRACO_works.pdf">over a hundred FRBs a year</a>. By continuing to work collaboratively with each other, different survey groups will be able to untangle the mysteries behind FRBs, how they form, and their host galaxy environments. </p>
<hr>
<p><em>CSIRO acknowledges the Wajarri Yamaji as the Traditional Owners and native title holders of the Inyarrimanha Ilgari Bundara, our Murchison Radio-astronomy Observatory site, where ASKAP is located.</em></p><img src="https://counter.theconversation.com/content/203557/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcin Glowacki does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
One of the few examples of a fast radio burst and the slow-moving, star forming gas in its origin galaxy has been linked together – thanks to observations from a CSIRO telescope.
Marcin Glowacki, Research Associate, Curtin University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/204339
2023-05-22T12:27:17Z
2023-05-22T12:27:17Z
Gravitational wave detector LIGO is back online after 3 years of upgrades – how the world’s most sensitive yardstick reveals secrets of the universe
<figure><img src="https://images.theconversation.com/files/527292/original/file-20230519-29-jhi1qv.jpg?ixlib=rb-1.1.0&rect=335%2C178%2C6276%2C2651&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">When two massive objects – like black holes or neutron stars – merge, they warp space and time. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/gravitational-waves-illustration-royalty-free-illustration/685026451?phrase=gravitational+waves&adppopup=true">Mark Garlick/Science Photo Library via Getty Images</a></span></figcaption></figure><p>After a three-year hiatus, scientists in the U.S. have just turned on detectors capable of <a href="https://observing.docs.ligo.org/plan/">measuring gravitational waves</a> – tiny ripples in space itself that travel through the universe. </p>
<p>Unlike light waves, gravitational waves are nearly <a href="https://www.ligo.caltech.edu/page/why-detect-gw">unimpeded by the galaxies, stars, gas and dust</a> that fill the universe. This means that by measuring gravitational waves, <a href="https://scholar.google.com/citations?user=33fO9GoAAAAJ&hl=en&oi=sra">astrophysicists like me</a> can peek directly into the heart of some of these most spectacular phenomena in the universe. </p>
<p>Since 2020, the Laser Interferometric Gravitational-Wave Observatory – commonly known as <a href="https://www.ligo.caltech.edu">LIGO</a> – has been sitting dormant while it underwent some exciting upgrades. These improvements will <a href="https://doi.org/10.1103/PhysRevX.13.011048">significantly boost the sensitivity</a> of LIGO and should allow the facility to observe more-distant objects that produce smaller ripples in <a href="https://theconversation.com/why-does-gravity-pull-us-down-and-not-up-162141">spacetime</a>.</p>
<p>By detecting more events that create gravitational waves, there will be more opportunities for astronomers to also observe the light produced by those same events. Seeing an event <a href="https://theconversation.com/ligo-announcement-vaults-astronomy-out-of-its-silent-movie-era-into-the-talkies-85727">through multiple channels of information</a>, an approach called <a href="https://doi.org/10.1038/s42254-019-0101-z">multi-messenger astronomy</a>, provides astronomers <a href="https://doi.org/10.3847/2041-8213/aa91c9">rare and coveted opportunities</a> to learn about physics far beyond the realm of any laboratory testing.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the Sun and Earth warping space." src="https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=440&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=440&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527293/original/file-20230519-25-cqwibh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=440&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">According to Einstein’s theory of general relativity, massive objects warp space around them.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/gravity-and-general-theory-of-relativity-concept-royalty-free-image/923504630?phrase=gravity+general+relativity&adppopup=true">vchal/iStock via Getty Images</a></span>
</figcaption>
</figure>
<h2>Ripples in spacetime</h2>
<p>According to <a href="https://theconversation.com/why-does-gravity-pull-us-down-and-not-up-162141">Einstein’s theory of general relativity</a>, mass and energy warp the shape of space and time. The bending of spacetime determines how objects move in relation to one another – what people experience as gravity. </p>
<p>Gravitational waves are created when massive objects like black holes or neutron stars merge with one another, producing sudden, large changes in space. The process of space warping and flexing sends ripples across the universe like a <a href="https://www.ligo.caltech.edu/page/what-are-gw">wave across a still pond</a>. These waves travel out in all directions from a disturbance, minutely bending space as they do so and ever so slightly changing the distance between objects in their way. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_C5Bl_hE8fM?wmode=transparent&start=17" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">When two massive objects – like a black hole or a neutron star – get close together, they rapidly spin around each other and produce gravitational waves. The sound in this NASA visualization represents the frequency of the gravitational waves.</span></figcaption>
</figure>
<p>Even though the astronomical events that produce gravitational waves involve some of the most massive objects in the universe, the stretching and contracting of space is infinitesimally small. A strong gravitational wave passing through the Milky Way may only change the diameter of the entire galaxy by three feet (one meter).</p>
<h2>The first gravitational wave observations</h2>
<p>Though first predicted by Einstein in 1916, scientists of that era had little hope of measuring the tiny changes in distance postulated by the theory of gravitational waves.</p>
<p>Around the year 2000, scientists at Caltech, the Massachusetts Institute of Technology and other universities around the world finished constructing what is essentially the most precise ruler ever built – the <a href="https://doi.org/10.1088/0034-4885/72/7/076901">LIGO observatory</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An L-shaped facility with two long arms extending out from a central building." src="https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527294/original/file-20230519-21-zdmud0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The LIGO detector in Hanford, Wash., uses lasers to measure the minuscule stretching of space caused by a gravitational wave.</span>
<span class="attribution"><a class="source" href="https://www.ligo.org/multimedia/gallery/lho-images/Aerial5.jpg">LIGO Laboratory</a></span>
</figcaption>
</figure>
<p><a href="https://www.ligo.caltech.edu/page/what-is-ligo">LIGO is comprised of two separate observatories</a>, with one located in Hanford, Washington, and the other in Livingston, Louisiana. Each observatory is shaped like a giant L with two, 2.5-mile-long (four-kilometer-long) arms extending out from the center of the facility at 90 degrees to each other.</p>
<p>To measure gravitational waves, researchers shine a laser from the center of the facility to the base of the L. There, the laser is split so that a beam travels down each arm, reflects off a mirror and returns to the base. If a gravitational wave passes through the arms while the laser is shining, the two beams will return to the center at ever so slightly different times. By measuring this difference, physicists can discern that a gravitational wave passed through the facility.</p>
<p><a href="https://doi.org/10.1088/0034-4885/72/7/076901">LIGO began operating</a> in the early 2000s, but it was not sensitive enough to detect gravitational waves. So, in 2010, the LIGO team temporarily shut down the facility to perform <a href="https://doi.org/10.1088/0264-9381/32/7/074001">upgrades to boost sensitivity</a>. The upgraded version of LIGO started <a href="https://theconversation.com/what-happens-when-ligo-texts-you-to-say-its-detected-one-of-einsteins-predicted-gravitational-waves-53259">collecting data in 2015 and almost immediately</a> <a href="https://doi.org/10.1103/PhysRevLett.116.061102">detected gravitational waves</a> produced from the merger of two black holes. </p>
<p>Since 2015, LIGO has completed <a href="https://observing.docs.ligo.org/plan/#timeline">three observation runs</a>. The first, run O1, lasted about four months; the second, O2, about nine months; and the third, O3, ran for 11 months before the COVID-19 pandemic forced the facilities to close. Starting with run O2, LIGO has been jointly observing with an <a href="https://doi.org/10.1088/0264-9381/32/2/024001">Italian observatory called Virgo</a>.</p>
<p>Between each run, scientists improved the physical components of the detectors and data analysis methods. By the end of run O3 in March 2020, researchers in the LIGO and Virgo collaboration had detected <a href="https://doi.org/10.48550/arXiv.2111.03606">about 90 gravitational waves</a> from the merging of black holes and neutron stars.</p>
<p>The observatories have still <a href="https://dcc.ligo.org/LIGO-P1200087/public">not yet achieved their maximum design sensitivity</a>. So, in 2020, both observatories shut down for upgrades <a href="https://www.ligo.caltech.edu/news/ligo20200326">yet again</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two people in white lab outfits working on complicated machinery." src="https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527297/original/file-20230519-27-8k3n94.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Upgrades to the mechanical equipment and data processing algorithms should allow LIGO to detect fainter gravitational waves than in the past.</span>
<span class="attribution"><a class="source" href="https://www.ligo.caltech.edu/image/ligo20190326b">LIGO/Caltech/MIT/Jeff Kissel</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Making some upgrades</h2>
<p>Scientists have been working on <a href="https://dcc-llo.ligo.org/public/0182/G2200736/001/UpdateonLVKDetectors.pdf">many technological improvements</a>.</p>
<p>One particularly promising upgrade involved adding a 1,000-foot (300-meter) <a href="https://spie.org/news/photonics-focus/marapr-2023/squeezing-light-for-ligo?SSO=1">optical cavity</a> to improve a <a href="https://doi.org/10.1088/1361-6633/aab906">technique called squeezing</a>. Squeezing allows scientists to reduce detector noise using the quantum properties of light. With this upgrade, the LIGO team should be able to detect much weaker gravitational waves than before.</p>
<p><a href="https://igc.psu.edu/people/bio/crh184/#nav-members">My teammates and I</a> are data scientists in the LIGO collaboration, and we have been working on a number of different upgrades to <a href="https://doi.org/10.48550/arXiv.2305.05625">software used to process LIGO data</a> and the algorithms that recognize <a href="https://doi.org/10.48550/arXiv.2305.06286">signs of gravitational waves in that data</a>. These algorithms function by searching for patterns that match <a href="https://doi.org/10.48550/arXiv.2211.16674">theoretical models of millions</a> of possible black hole and neutron star merger events. The improved algorithm should be able to more easily pick out the faint signs of gravitational waves from background noise in the data than the previous versions of the algorithms.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A GIF showing a star brightening over a few days." src="https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=641&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=641&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=641&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=805&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=805&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527298/original/file-20230519-27-h3pm1c.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=805&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronomers have captured both the gravitational waves and light produced by a single event, the merger of two neutron stars. The change in light can be seen over the course of a few days in the top right inset.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/press-release/nasa-missions-catch-first-light-from-a-gravitational-wave-event">Hubble Space Telescope, NASA and ESA</a></span>
</figcaption>
</figure>
<h2>A hi-def era of astronomy</h2>
<p>In early May 2023, LIGO began a short test run – called an engineering run – to make sure everything was working. On May 18, LIGO detected gravitational waves likely <a href="https://gcn.nasa.gov/circulars/33813">produced from a neutron star merging into a black hole</a>.</p>
<p>LIGO’s 20-month observation run 04 will officially <a href="https://www.ligo.org/news/images/ER15-newsitem.pdf">start on May 24,</a> and it will later be joined by Virgo and a new Japanese observatory – the Kamioka Gravitational Wave Detector, or KAGRA. </p>
<p>While there are many scientific goals for this run, there is a particular focus on detecting and localizing gravitational waves in real time. If the team can identify a gravitational wave event, figure out where the waves came from and alert other astronomers to these discoveries quickly, it would enable astronomers to point other telescopes that collect visible light, radio waves or other types of data at the source of the gravitational wave. Collecting multiple channels of information on a single event – <a href="https://doi.org/10.3847/1538-4357/ab0e8f">multi-messenger astrophysics</a> – is like adding color and sound to a black-and-white silent film and can provide a much deeper understanding of astrophysical phenomena.</p>
<p>Astronomers have only observed a single event <a href="https://doi.org/10.3847/2041-8213/aa91c9">in both gravitational waves and visible light</a> to date – the merger of <a href="https://theconversation.com/ligo-announcement-vaults-astronomy-out-of-its-silent-movie-era-into-the-talkies-85727">two neutron stars seen in 2017</a>. But from this single event, physicists were able to study the <a href="https://doi.org/10.1038/nature24471">expansion of the universe</a> and confirm the origin of some of the universe’s most energetic events known as <a href="https://doi.org/10.3847/2041-8213/aa920c">gamma-ray bursts</a>.</p>
<p>With run O4, astronomers will have access to the most sensitive gravitational wave observatories in history and hopefully will collect more data than ever before. My colleagues and I are hopeful that the coming months will result in one – or perhaps many – multi-messenger observations that will push the boundaries of modern astrophysics.</p><img src="https://counter.theconversation.com/content/204339/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chad Hanna receives funding from the National Science Foundation and NASA.</span></em></p>
Upgrades to the hardware and software of the advanced observatory should allow astrophysicists to detect much fainter gravitational waves than before.
Chad Hanna, Professor of Physics, Penn State
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/204351
2023-05-03T12:10:32Z
2023-05-03T12:10:32Z
AI is helping astronomers make new discoveries and learn about the universe faster than ever before
<figure><img src="https://images.theconversation.com/files/523645/original/file-20230501-18-4e90m3.jpg?ixlib=rb-1.1.0&rect=0%2C299%2C4895%2C3031&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The sky is big and full of information that AI tools can help astronomers unlock. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/paul-wild-observatory-under-starry-sky-royalty-free-image/637273906?phrase=telescope+with+milky+way&adppopup=true">Yuga Kurita/Moment via Getty Images</a></span></figcaption></figure><p>The famous first image of a black hole <a href="https://doi.org/10.3847/2041-8213/acc32d">just got two times sharper</a>. A research team used artificial intelligence to dramatically improve upon <a href="https://doi.org/10.3847/2041-8213/ab0ec7">its first image</a> from 2019, which now shows the black hole at the center of the M87 galaxy as darker and bigger than the first image depicted.</p>
<p>I’m an <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">astronomer</a> who studies and has written about <a href="https://wwnorton.com/books/9780393343861">cosmology</a>, <a href="https://wwnorton.com/books/9780393357509">black holes</a> and <a href="https://www.penguinrandomhouse.com/books/718149/worlds-without-end-by-chris-impey/">exoplanets</a>. Astronomers have been using AI for decades. In fact, in 1990, astronomers from the University of Arizona, where I am a professor, were among the <a href="https://www.datasciencecentral.com/the-evolution-of-astronomical-ai/">first to use a type of AI called a neural network</a> to study the shapes of galaxies. </p>
<p>Since then, AI has spread into every field of astronomy. As the technology has become more powerful, AI algorithms have begun helping astronomers tame massive data sets and discover new knowledge about the universe.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A group of radio antennas pointed at the sky." src="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523641/original/file-20230501-18-3sjj1h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Astronomy is no longer limited to just optical images – radio telescopes produce huge amounts of data that researchers need to process.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/observatory-antenna-in-the-sunse-royalty-free-image/1309400138?phrase=astronomy+data&adppopup=true">Wenbin/Moment via Getty Images</a></span>
</figcaption>
</figure>
<h2>Better telescopes, more data</h2>
<p>As long as astronomy has been a science, it has involved trying to make sense of the multitude of objects in the night sky. That was relatively simple when the only tools were the naked eye or a simple telescope, and all that could be seen were a few thousand stars and a handful of planets.</p>
<p>A hundred years ago, Edwin Hubble used newly built telescopes to show that the universe is filled with not just stars and clouds of gas, <a href="https://www.nasa.gov/content/about-story-edwin-hubble">but countless galaxies</a>. As telescopes have continued to improve, the sheer number of celestial objects humans can see and the <a href="https://events.asiaa.sinica.edu.tw/school/20170904/talk/djorgovski1.pdf">amount of data</a> astronomers need to sort through have both grown exponentially, too.</p>
<p>For example, the soon-to-be-completed <a href="https://www.lsst.org/about">Vera Rubin Observatory</a> in Chile will make images so large that it would take 1,500 high-definition TV screens to view each one in its entirety. Over 10 years it is expected to generate 0.5 exabytes of data – about 50,000 times the amount of information held in all of the books contained within the Library of Congress. </p>
<p>There are 20 telescopes with mirrors larger than 20 feet (6 meters) in diameter. AI algorithms are the only way astronomers could ever hope to work through all of the data available to them today. There are a number of ways AI is proving useful in processing this data.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A sky filled with galaxies." src="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523642/original/file-20230501-292-iuhviz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One of the earliest uses of AI in astronomy was to pick out the multitude of faint galaxies hidden in the background of images.</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/nasawebbtelescope/52777397541/">ESA/Webb, NASA & CSA, J. Rigby</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Picking out patterns</h2>
<p>Astronomy often involves looking for needles in a haystack. About 99% of the pixels in an astronomical image contain background radiation, light from other sources or the blackness of space – only 1% have the subtle shapes of faint galaxies. </p>
<p>AI algorithms – in particular, neural networks that use many interconnected nodes and are able to learn to recognize patterns – are perfectly suited for picking out the patterns of galaxies. Astronomers began <a href="https://doi.org/10.1111/j.1365-2966.2010.16713.x">using neural networks to classify galaxies</a> in the early 2010s. Now the algorithms <a href="https://www.nao.ac.jp/en/news/science/2020/20200811-subaru.html">are so effective</a> that they can classify galaxies with an accuracy of 98%.</p>
<p>This story has been repeated in other areas of astronomy. Astronomers working on SETI, the Search for Extraterrestrial Intelligence, use radio telescopes to look for signals from distant civilizations. Early on, radio astronomers scanned charts by eye to <a href="https://earthsky.org/space/wow-signal-explained-comets-antonio-paris/">look for anomalies</a> that couldn’t be explained. More recently, researchers harnessed 150,000 personal computers and 1.8 million citizen scientists to look for artificial <a href="https://www.nytimes.com/2020/03/23/science/seti-at-home-aliens.html">radio signals</a>. Now, researchers are using AI to sift through reams of data much more quickly and thoroughly than people can. This has allowed SETI efforts to cover more ground while also greatly reducing the <a href="https://doi.org/10.1038/s41550-022-01872-z">number of false positive signals</a>.</p>
<p>Another example is the search for exoplanets. Astronomers discovered most of the <a href="https://exoplanets.nasa.gov/">5,300 known exoplanets</a> by measuring a dip in the amount of light coming from a star <a href="https://exoplanets.nasa.gov/resources/2338/exoplanet-detection-transit-method/">when a planet passes in front of it</a>. AI tools can now pick out the signs of an exoplanet with <a href="https://doi.org/10.48550/arXiv.2011.14135">96% accuracy</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A planet near a dim red star." src="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523643/original/file-20230501-16-xeiogk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">AI tools can help astronomers discover new exoplanets like TRAPPIST-1 b.</span>
<span class="attribution"><a class="source" href="https://flickr.com/photos/nasawebbtelescope/52775409328/">NASA, ESA, CSA, Joseph Olmsted (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Making new discoveries</h2>
<p>AI has proved itself to be excellent at identifying known objects – like galaxies or exoplanets – that astronomers tell it to look for. But it is also quite powerful at finding objects or phenomena that are theorized but have not yet been discovered in the real world.</p>
<p>Teams have used this approach to detect <a href="https://www.sciencedaily.com/releases/2023/02/230207144222.htm">new exoplanets</a>, learn about the <a href="https://www.quantamagazine.org/with-ai-astronomers-dig-up-the-stars-that-birthed-the-milky-way-20230328/">ancestral stars</a> that led to the formation and growth of the Milky Way, and predict the signatures of new types of <a href="https://cerncourier.com/a/gravitational-wave-astronomy-turns-to-ai/">gravitational waves</a>.</p>
<p>To do this, astronomers first use AI to convert theoretical models into observational signatures – including realistic levels of noise. They then use machine learning to sharpen the ability of AI to detect the predicted phenomena.</p>
<p>Finally, radio astronomers have also been using AI algorithms to sift through signals that don’t correspond to known phenomena. Recently a team from South Africa found a <a href="https://www.biznews.com/global-citizen/2023/04/06/machine-learnings-discovery-astronomy">unique object</a> that may be a remnant of the explosive merging of two supermassive black holes. If this proves to be true, the data will allow a new test of general relativity – Albert Einstein’s <a href="https://theconversation.com/why-does-gravity-pull-us-down-and-not-up-162141">description of space-time</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two side-by-side images of an orange circular haze around a dark center." src="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=301&fit=crop&dpr=1 600w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=301&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=301&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=378&fit=crop&dpr=1 754w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=378&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/523644/original/file-20230501-22-dihfie.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=378&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The team that first imaged a black hole, at left, used AI to generate a sharper version of the image, at right, showing the black hole to be larger than originally thought.</span>
<span class="attribution"><a class="source" href="https://iopscience.iop.org/article/10.3847/1538-4357/acaa9a/meta">Medeiros et al 2023</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Making predictions and plugging holes</h2>
<p>As in many areas of life recently, generative AI and large language models like ChatGPT are also making waves in the astronomy world.</p>
<p>The team that created the first image of a black hole in 2019 used a <a href="https://doi.org/10.3847/2041-8213/acc32d">generative AI to produce its new image</a>. To do so, it first taught an AI how to recognize black holes by feeding it simulations of many kinds of black holes. Then, the team used the AI model it had built to fill in gaps in the massive amount of data collected by the radio telescopes on the black hole M87. </p>
<p>Using this simulated data, the team was able to create a new image that is two times sharper than the original and is fully consistent with the predictions of general relativity.</p>
<p>Astronomers are also turning to AI to help tame the complexity of modern research. A team from the Harvard-Smithsonian Center for Astrophysics created a <a href="https://doi.org/10.48550/arXiv.2212.00744">language model called astroBERT</a> to read and organize 15 million scientific papers on astronomy. Another team, based at NASA, has even proposed using AI to <a href="https://www.technologyreview.com/2021/09/20/1035890/ai-predict-astro2020-decadal-survey/">prioritize astronomy projects</a>, a process that astronomers engage in every 10 years.</p>
<p>As AI has progressed, it has become an essential tool for astronomers. As telescopes get better, as data sets get larger and as AIs continue to improve, it is likely that this technology will play a central role in future discoveries about the universe.</p><img src="https://counter.theconversation.com/content/204351/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation and Epic Games.</span></em></p>
Artificial intelligence tools are making waves in almost every aspect of life, and astronomy is no different. An astronomer explains the history and future of AI in understanding the universe.
Chris Impey, University Distinguished Professor of Astronomy, University of Arizona
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/199688
2023-04-05T15:45:25Z
2023-04-05T15:45:25Z
Astronomers used machine learning to mine data from South Africa’s MeerKAT telescope: what they found
<figure><img src="https://images.theconversation.com/files/515439/original/file-20230315-28-t0q61o.jpg?ixlib=rb-1.1.0&rect=94%2C111%2C715%2C558&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">SAURON: radio intensity (purple) from MeerKAT overlaid on an optical image from the Dark Energy Survey.</span> <span class="attribution"><span class="source">Michelle Lochner / The Dark Energy Survey Collaboration 2005</span></span></figcaption></figure><p>New telescopes with unprecedented sensitivity and resolution are being unveiled around the world – and beyond. Among them are the <a href="https://giantmagellan.org/">Giant Magellan Telescope</a> under construction in Chile, and the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a>, which is parked a million and a half kilometres out in space. </p>
<p>This means there is a wealth of data available to scientists that simply wasn’t there before. The raw data off just a single observation from the <a href="https://www.sarao.ac.za/science/meerkat/">MeerKAT radio telescope</a> in South Africa’s Northern Cape province can measure a terabyte. That’s enough to fill a laptop computer’s hard drive. <a href="https://theconversation.com/a-big-moment-for-africa-why-the-meerkat-and-astronomy-matter-99714">MeerKAT</a> is an array of 64 large antenna dishes. It uses radio signals from space to study the evolution of the universe and everything it contains – galaxies, for example. Each dish is said to generate as much <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">data in one second</a> as you’d find on a DVD.</p>
<p><a href="https://www.britannica.com/technology/machine-learning">Machine learning</a> is helping astronomers to work through this data quickly and more accurately than poring over it manually. Perhaps surprisingly, despite increasing reliance on computers, up until recently the discovery of rare or new astrophysical phenomena has completely relied on human inspection of the data. </p>
<p>Machine learning is essentially a set of algorithms designed to automatically learn patterns and models from data. Because we astronomers aren’t sure what we’re going to find – we don’t know what we don’t know – we also design algorithms to look out for anomalies that don’t fit known parameters or “labels”.</p>
<p>This approach allowed my colleagues and I <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stad074/6985618?redirectedFrom=fulltext">to spot</a> a previously overlooked object in data from MeerKAT. It sits some seven billion light years from Earth (a light year is a measure of how far light would travel in a year). From what we know of the object so far, it has many of the makings of what’s known as an Odd Radio Circle (ORC). </p>
<p>Odd Radio Circles are identifiable by their <a href="https://astronomy.com/news/2022/05/understanding-the-origins-of-orcs-odd-radio-circles">strange, ring-like structure</a>. Only a handful of these circles have been detected since the first discovery in 2019, so not much is known about them yet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/combined-power-of-two-telescopes-is-helping-crack-the-mystery-of-eerie-rings-in-the-sky-180595">Combined power of two telescopes is helping crack the mystery of eerie rings in the sky</a>
</strong>
</em>
</p>
<hr>
<p>In a new <a href="https://academic.oup.com/mnras/advance-article-abstract/doi/10.1093/mnras/stad074/6985618?redirectedFrom=fulltext">paper</a> we outline the features of our potential Odd Radio Circle, which we’ve named SAURON (a Steep and Uneven Ring Of Non-thermal Radiation). SAURON is, to our knowledge, the first scientific discovery made in MeerKAT data with machine learning. (There have been a handful of other discoveries assisted by machine learning in astronomy.)</p>
<p>Not only is discovering something new incredibly exciting, new discoveries are critical for challenging our understanding of the <a href="https://www.britannica.com/science/Cosmos-astronomy">cosmos</a>. These new objects may match our theories of how galaxies form and evolve, or we may need to change how we see the universe. New discoveries of anomalous astrophysical objects help science to make progress. </p>
<h2>Identifying anomalies</h2>
<p>We spotted SAURON in data from the <a href="https://arxiv.org/abs/2111.05673">MeerKAT Galaxy Cluster Legacy Survey</a>. The survey is a programme of observations conducted with South Africa’s MeerKAT telescope, a precursor to the <a href="https://www.skao.int/">Square Kilometre Array</a>. The array is a global project to build the world’s largest and most sensitive radio telescope within the coming decade, co-located in South Africa and Australia. </p>
<p>The survey was conducted between June 2018 and June 2019. It zeroed in on some 115 galaxy clusters, each made up of hundreds or even thousands of galaxies.</p>
<p>That’s a lot of data to sift through – which is where machine learning comes in. </p>
<p>We developed and used a coding framework which we called <a href="https://arxiv.org/abs/2010.11202">Astronomaly</a> to sort through the data. Astronomaly ranked unknown objects according to an anomaly scoring system. The human team then manually evaluated the 200 anomalies that interested us most. Here, we drew on vast collective expertise to make sense of the data. </p>
<p>It was during this part of the process that we identified SAURON. Instead of having to look at 6,000 individual images, we only had to look through the first 60 that Astronomaly flagged as anomalous to pick up SAURON. </p>
<p>But the question remains: what, exactly, have we found?</p>
<h2>Is SAURON an Odd Radio Circle?</h2>
<p>We know very little about Odd Radio Circles. It is currently thought that their bright, blast-like emission is the wreckage of a huge <a href="https://theconversation.com/odd-radio-circles-that-baffled-astronomers-are-likely-explosions-from-distant-galaxies-178290">explosion</a> in their host galaxies.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Purple roughly circular shape on dark background" src="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=561&fit=crop&dpr=1 754w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=561&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/517713/original/file-20230327-23-vb272r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=561&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">SAURON.</span>
<span class="attribution"><span class="source">Michelle Lochner</span></span>
</figcaption>
</figure>
<p>The name SAURON captures the fundamentals of the object’s make-up. “Steep” refers to its spectral slope, indicating that at higher radio frequencies the “source” (or object) very quickly grows fainter. “Ring” refers to the shape. And the “Non-Thermal Radiation” refers to the type of radiation, suggesting that there must be particles accelerating in powerful magnetic fields. SAURON is at least 1.2 million light years across, about 20 times the size of the Milky Way.</p>
<p>But SAURON doesn’t tick all the right boxes for us to say that it’s definitely an Odd Radio Circle. We detected a host galaxy but can find no evidence of radio emissions with the wavelengths and frequency that match those of host galaxies of the other known ORCs. </p>
<p>And even though SAURON has a number of features in common with Odd Radio Circle1 – the first Odd Radio Circle spotted – it differs in others. Its strange shape and its oddly behaving magnetic fields don’t align well with the main structure.</p>
<p>One of the most exciting possibilities is that SAURON is a remnant of the explosive merger of two supermassive black holes. These are incredibly dense objects at the centre of galaxies such as our Milky Way that could cause a massive explosion when galaxies collide. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-were-probing-the-secrets-of-a-giant-black-hole-at-our-galaxys-centre-108181">How we're probing the secrets of a giant black hole at our galaxy's centre</a>
</strong>
</em>
</p>
<hr>
<h2>More to come</h2>
<p>More investigation is required to unravel the mystery. Meanwhile, machine learning is quickly becoming an indispensable tool to find more strange objects by sorting through enormous datasets from telescopes. With this tool, we can expect to unveil more of what the universe is hiding.</p><img src="https://counter.theconversation.com/content/199688/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michelle Lochner receives funding from the National Research Foundation and the Department of Science and Innovation. </span></em></p>
Machine learning is becoming an indispensable tool in astronomy by sorting through enormous datasets from telescopes.
Michelle Lochner, Staff Scientist at the South African Radio Astronomy Observatory and Senior Lecturer in Astronomy, University of the Western Cape
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/199831
2023-02-15T17:16:17Z
2023-02-15T17:16:17Z
Black holes may be the source of mysterious dark energy that makes up most of the universe
<figure><img src="https://images.theconversation.com/files/509870/original/file-20230213-4443-xsmxpu.jpg?ixlib=rb-1.1.0&rect=313%2C0%2C2251%2C1483&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">black hole</span> </figcaption></figure><p><a href="https://www.nasa.gov/vision/universe/starsgalaxies/black_hole_description.html">Black holes</a> could explain a mysterious form of energy that makes up most of the universe, according to astronomers. The existence of <a href="https://en.wikipedia.org/wiki/Dark_energy">“dark energy”</a> has been inferred from observations of stars and galaxies, but no one has been able to explain what it is, or where it comes from.</p>
<p>The stuff, or matter, that makes up the familiar world around us is just 5% of everything in the universe. Another 27% is <a href="https://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy">dark matter</a>, a shadowy counterpart of ordinary matter which does not emit, reflect or absorb light. However, the majority of the cosmos – around 68% – is dark energy.</p>
<p>The new evidence that black holes could be the source of dark energy is described in <a href="https://iopscience.iop.org/article/10.3847/2041-8213/acb704">a scientific paper</a> published in The Astrophysical Journal Letters. The study is the work of 17 astronomers in nine countries and was led by the University of Hawaii. The collaboration included researchers in the UK, based at STFC RAL Space, The Open University, and Imperial College London.</p>
<p>Searching through data spanning nine billion years of cosmic history, the astronomers have uncovered the first evidence of <a href="https://physicsworld.com/a/cosmological-coupling-is-making-black-holes-bigger-study-suggests/">“cosmological coupling”</a>, which would mean that the growth of black holes over time is linked to the expansion of the universe itself.</p>
<p>The idea that black holes might contain something called <a href="https://en.wikipedia.org/wiki/Vacuum_energy">vacuum energy</a> (a manifestation of dark energy) is not particularly new and in fact was discussed theoretically as far back as the 1960s. But this latest work assumes this energy (and therefore the mass of the black holes) would increase with time as the universe expands as a result of cosmological coupling.</p>
<p>The team calculated how much of the dark energy in the universe could be attributed to this process. They found that black holes could potentially explain the total amount of dark energy we measure in the universe today. The result could solve one of the most fundamental problems in modern cosmology.</p>
<h2>Rapid expansion</h2>
<p><a href="https://hubblesite.org/contents/articles/the-big-bang">Our universe began in a Big Bang</a> around 13.7 billion years ago. The energy from this explosion of space and time caused the universe to expand rapidly, with all the galaxies flying away from each other. However, we expect that this expansion would gradually slow down because of the effect of gravity on all the stuff in the cosmos.</p>
<p>This is the version of the universe we thought we lived in until the late 1990s, when the Hubble space telescope discovered something strange. Observations of distant exploding stars showed that, in the past, the universe <a href="https://en.wikipedia.org/wiki/Accelerating_expansion_of_the_universe">was actually expanding more slowly than it is today</a>. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gjwxnoPoEHQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The new discovery is explained by Chris Pearson of RAL Space and The Open University.</span></figcaption>
</figure>
<p>So the expansion of the universe has not been slowing due to gravity, as everyone thought, but instead has been accelerating. This was highly unexpected and astronomers struggled to explain it.</p>
<p>To account for this, it was proposed that a “dark energy” was responsible for pushing things apart more strongly than gravity pulled things together. The concept of dark energy was very similar to a mathematical construct Einstein had proposed but later discarded – a <a href="https://en.wikipedia.org/wiki/Cosmological_constant">“cosmological constant”</a> that opposed gravity and kept the universe from collapsing.</p>
<h2>Stellar explosions</h2>
<p>But what is dark energy? The solution, it seems, might lie with another cosmic mystery: black holes. Black holes are commonly born when <a href="https://public.nrao.edu/ask/when-does-a-neutron-star-or-black-hole-form-after-a-supernova/">massive stars explode and die at the ends of their lives</a>. The gravity and pressure in these violent explosions compresses vast amounts of material into a small space. For instance, a star about the same mass as our sun would be squashed into a space of just a few tens of kilometres. </p>
<p>A black hole’s gravitational pull is so strong that not even light can escape it – everything gets sucked in. At the centre of the black hole is a place called a <a href="https://bigthink.com/starts-with-a-bang/singularity-black-hole/">singularity</a>, where matter is crushed into a point of infinite density. The problem is that singularities are a mathematical construct that should not exist.</p>
<figure class="align-center ">
<img alt="The Andromeda galaxy" src="https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/509866/original/file-20230213-14-3kjqam.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dark energy explains why the expansion of the universe is speeding up.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/galex/pia15416.html">NASA/JPL-Caltech</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The black holes nestled at the centres of galaxies are much heftier than those born when stars die violently. These galactic “supermassive” black holes can weigh millions to billions of times the mass of our Sun.</p>
<p>All black holes increase in size by accumulating matter, by swallowing stars that get too close, or by merging with other black holes. So we expect them to get bigger as the universe gets older.</p>
<p>In the latest paper, the team looked at supermassive black holes in the centres of galaxies and found that these black holes gain mass over billions of years. </p>
<h2>Radical rethink</h2>
<p>The team compared observations of <a href="https://en.wikipedia.org/wiki/Elliptical_galaxy">elliptical galaxies</a>, which lack star formation, in the past and in the present day. These dead galaxies have used up all their fuel so any increase in their black hole mass over this time cannot be ascribed to the normal processes by which black holes grow by accumulating matter.</p>
<p>Instead, the team proposed that these black holes actually contain vacuum energy and that they are “coupled” to the expansion of the universe, so that they increase in mass as the universe expands. </p>
<figure class="align-center ">
<img alt="Visualisation of a black hole" src="https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&rect=17%2C34%2C3782%2C2098&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/509864/original/file-20230213-18-s6s06q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A visualisation of a black hole, which could play a role in dark energy.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/goddard/2019/nasa-visualization-shows-a-black-hole-s-warped-world">NASA’s Goddard Space Flight Center/Jeremy Schnittman</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>This model neatly provides a possible origin for the dark energy in the universe. It also circumvents the mathematical problems that affect some studies of black holes, because it avoids the need for a singularity at the centre.</p>
<p>The team also calculated how much of the dark energy in the universe could be attributed to this process of coupling. They concluded that it would be possible for black holes to provide the necessary amount of vacuum energy to account for all the dark energy that we measure in the universe today. </p>
<p>This would not only explain the origin of dark energy in the universe but would also make us radically rethink our understanding of black holes and their role in the cosmos.</p>
<p>Much more work needs to be done to test and confirm this idea, both from observations of the sky and from theory. But we may at last be seeing a new way to solve the problem of dark energy.</p><img src="https://counter.theconversation.com/content/199831/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Pearson receives funding from STFC and is head of astronomy at STFC RAL Space and a visiting fellow at the Open University </span></em></p><p class="fine-print"><em><span>Dave Clements receives funding from STFC and the UKSA and works at Imperial College London.</span></em></p>
Astronomers have found that mysterious dark energy may originate in black holes.
Chris Pearson, Astronomy Group Lead, Space Operations Division at RAL Space, and Visiting Fellow, The Open University
Dave Clements, Reader in Astrophysics, Imperial College London
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/198996
2023-02-02T19:15:43Z
2023-02-02T19:15:43Z
Why do black holes twinkle? We studied 5,000 star-eating behemoths to find out
<figure><img src="https://images.theconversation.com/files/507733/original/file-20230201-15-6lbgd6.jpg?ixlib=rb-1.1.0&rect=222%2C151%2C2477%2C1637&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Somchat Parkaythong/Shutterstock</span></span></figcaption></figure><p>Black holes are bizarre things, even by the standards of astronomers. Their mass is so great, it bends space around them so tightly that nothing can escape, even light itself.</p>
<p>And yet, despite their famous blackness, some black holes are quite visible. The gas and stars these galactic vacuums devour are sucked into a glowing disc before their one-way trip into the hole, and these discs can shine more brightly than entire galaxies. </p>
<p>Stranger still, these black holes twinkle. The brightness of the glowing discs can fluctuate from day to day, and nobody is entirely sure why.</p>
<p>We piggy-backed on NASA’s asteroid defence effort to watch more than 5,000 of the fastest-growing black holes in the sky for five years, in an attempt to understand why this twinkling occurs. In <a href="https://rdcu.be/c4Je0">a new paper in Nature Astronomy</a>, we report our answer: a kind of turbulence driven by friction and intense gravitational and magnetic fields. </p>
<h2>Gigantic star-eaters</h2>
<p>We study supermassive black holes, the kind that sit at the centres of galaxies and are as massive as millions or billions of Suns. </p>
<p>Our own galaxy, the Milky Way, has one of these giants at its centre, with a mass of about four million Suns. For the most part, the 200 billion or so stars that make up the rest of the galaxy (including our Sun) happily orbit around the black hole at the centre.</p>
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Read more:
<a href="https://theconversation.com/are-black-holes-time-machines-yes-but-theres-a-catch-195418">Are black holes time machines? Yes, but there's a catch</a>
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</em>
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<p>However, things are not so peaceful in all galaxies. When pairs of galaxies pull on each other via gravity, many stars may end up tugged too close to their galaxy’s black hole. This ends badly for the stars: they are torn apart and devoured.</p>
<p>We are confident this must have happened in galaxies with black holes that weigh as much as a billion suns, because we can’t imagine how else they could have grown so large. It may also have happened in the Milky Way in the past.</p>
<p>Black holes can also feed in a slower, more gentle way: by sucking in clouds of gas blown out by geriatric stars known as red giants.</p>
<h2>Feeding time</h2>
<p>In our new study, we looked closely at the feeding process among the 5,000 fastest-growing black holes in the Universe. </p>
<p>In earlier studies, we discovered the black holes with the most voracious appetite. Last year, we found a black hole that eats <a href="https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/discovery-of-the-most-luminous-quasar-of-the-last-9-gyr/F7FEDC02A19FE9CA90A116552CC6BE14">an Earth’s-worth of stuff every second</a>. In 2018, we found one that eats <a href="https://www.cambridge.org/core/journals/publications-of-the-astronomical-society-of-australia/article/discovery-of-the-most-ultraluminous-qso-using-gaia-skymapper-and-wise/6FB5687AE7326F09557AD625C2889A0F">a whole Sun every 48 hours</a>.</p>
<p>But we have lots of questions about their actual feeding behaviour. We know material on its way into the hole spirals into a glowing “accretion disc” that can be bright enough to outshine entire galaxies. These visibly feeding black holes are called quasars. </p>
<p>Most of these black holes are a long, long way away – much too far for us to see any detail of the disc. We have some images of accretion discs around nearby black holes, but they are merely breathing in some cosmic gas rather than feasting on stars.</p>
<figure class="align-center ">
<img alt="A blobby photo of a red-yellow ring around a central black hole." src="https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507563/original/file-20230201-14-cillry.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The glowing accretion disc around the black hole Sagittarius A*, at the centre of the Milky Way, was imaged in 2022.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso2208-eht-mwa/">EHT Collaboration</a></span>
</figcaption>
</figure>
<h2>Five years of flickering black holes</h2>
<p>In <a href="https://rdcu.be/c4Je0">our new work</a>, we used data from NASA’s ATLAS telescope in Hawaii. It scans the entire sky every night (weather permitting), monitoring for asteroids approaching Earth from the outer darkness. </p>
<p>These whole-sky scans also happen to provide a nightly record of the glow of hungry black holes, deep in the background. Our team put together a five-year movie of each of those black holes, showing the day-to-day changes in brightness caused by the bubbling and boiling glowing maelstrom of the accretion disc.</p>
<p>The twinkling of these black holes can tell us something about accretion discs. </p>
<p>In 1998, astrophysicists Steven Balbus and John Hawley proposed a theory of “<a href="https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.70.1">magneto-rotational instabilities</a>” that describes how magnetic fields can cause turbulence in the discs. If that is the right idea, then the discs should sizzle in regular patterns. They would twinkle in random patterns that unfold as the discs orbit. Larger discs orbit more slowly with a slow twinkle, while tighter and faster orbits in smaller discs twinkle more rapidly.</p>
<p>But would the discs in the real world prove this simple, without any further complexities? (Whether “simple” is the right word for turbulence in an ultra-dense, out-of-control environment embedded in intense gravitational and magnetic fields where space itself is bent to breaking point is perhaps a separate question.)</p>
<p>Using statistical methods we measured how much the light emitted from our 5,000 discs flickered over time. The pattern of flickering in each one looked somewhat different. </p>
<p>But when we sorted them by size, brightness and colour, we began to see intriguing patterns. We were able to determine the orbital speed of each disc – and once you set your clock to run at the disc’s speed, all the flickering patterns started to look the same. </p>
<p>This universal behaviour is indeed predicted by the theory of “magneto-rotational instabilities”.</p>
<p>That was comforting! It means these mind-boggling maelstroms are “simple” after all. </p>
<p>And it opens new possibilities. We think the remaining subtle differences between accretion discs occur because we are looking at them from different orientations.</p>
<p>The next step is to examine these subtle differences more closely and see whether they hold clues to discern a black hole’s orientation. Eventually, our future measurements of black holes could be even more accurate.</p><img src="https://counter.theconversation.com/content/198996/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christian Wolf receives funding from the Australian Research Council (ARC). He is a member of the Astronomical Society of Australia (ASA).</span></em></p>
While we can’t see inside a black hole, we can spot the intensely bright glowing disc that surrounds one. Now, we might better understand why these discs appear to ‘twinkle’.
Christian Wolf, Associate Professor, Astronomy & Astrophysics, Australian National University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/196649
2022-12-15T16:23:01Z
2022-12-15T16:23:01Z
How the James Webb Space Telescope has revealed a surprisingly bright, complex and element-filled early universe – podcast
<figure><img src="https://images.theconversation.com/files/501209/original/file-20221215-15338-7jlg2y.png?ixlib=rb-1.1.0&rect=5%2C191%2C1886%2C1613&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The James Webb Space Telescope is providing astronomers with images and data that reveal secrets from the earliest era of the universe.</span> <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/034/01G7DA5ADA2WDSK1JJPQ0PTG4A?news=true">NASA/STScI</a></span></figcaption></figure><p>If you want to know what happened in the earliest years of the universe, you are going to need a very big, very specialized telescope. Much to the joy of astronomers and space fans everywhere, the world has one – the <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-on-the-team-explains-how-to-send-a-giant-telescope-to-space-and-why-167516">James Webb Space Telescope</a>. </p>
<p>In this episode of “<a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a>,” we talk to three experts about what astronomers have learned about the first galaxies in the universe and how just six months of data from James Webb is already changing astronomy. </p>
<iframe src="https://embed.acast.com/60087127b9687759d637bade/639ae709691e1f00111140ea" frameborder="0" width="100%" height="190px"></iframe>
<p><iframe id="tc-infographic-561" class="tc-infographic" height="100" src="https://cdn.theconversation.com/infographics/561/4fbbd099d631750693d02bac632430b71b37cd5f/site/index.html" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>The James Webb Space Telescope successfully launched into space on Dec. 25, 2021. After about six months of travel, setup and calibration, the telescope began collecting data and NASA published the first <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">stunning images</a>.</p>
<p>One of Webb’s nicknames is the “<a href="https://theconversation.com/is-the-james-webb-space-telescope-finding-the-furthest-oldest-youngest-or-first-galaxies-an-astronomer-explains-187915">first light telescope</a>.” This is because Webb was specifically designed to be able to see as far back as possible into the earliest days of the universe and detect some of the first visible light. </p>
<p>You can see these galaxies in the <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">images NASA has released</a>. <a href="https://scholar.google.com/citations?user=AWluLnoAAAAJ&hl=en&oi=ao">Jonathan Trump</a>, an astronomer at the University of Connecticut, is on one of the teams working on some of the early James Webb data. He was watching the release of the first images live and noticed some things many nonastronomers might have missed. “In the background, behind these beautiful arcs and spirals and massive elliptical galaxies are these tiny, itty-bitty red smudges. That’s what I was most interested in, because those are some of the first galaxies in the universe.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two images showing a suite of galaxies with small boxes around faint red smudges." src="https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=247&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=247&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=247&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=310&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=310&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501213/original/file-20221215-22-oaoozi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=310&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This compound image shows some of the earliest galaxies ever seen, highlighted by the small boxes in the images on the left and right, and shown up close in the images in the center.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/goddard/2022/nasa-s-webb-draws-back-curtain-on-universe-s-early-galaxies">NASA, ESA, CSA, Tommaso Treu (UCLA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>To see any of these galaxies from the earliest days of the universe would be exciting, but right off the bat, <a href="https://scholar.google.com/citations?user=oXVDWEcAAAAJ&hl=en&oi=ao">Jeyhan Kartaltepe</a>, an astronomer at the Rochester Institute of Technology, found something exciting when she started digging into the data. </p>
<p>“One of the things we’ve learned is that there are more of these galaxies than we expected to see.” In addition to working on identifying these early galaxies, Kartaltepe has been using Webb’s incredible resolution to study their structure and shape. “We expect there to be discs because discs form pretty naturally in the universe whenever you have something that’s rotating. But we’ve been seeing a lot of them, which has been a bit of a surprise.”</p>
<p>In addition to noting the shape of the galaxies in the early universe, astronomers like Trump are starting to be able to assess the <a href="https://arxiv.org/pdf/2207.12388.pdf">chemical composition of these galaxies</a>. He does this by looking at the spectrum of light James Webb is collecting. “We look at these distant galaxies and we look for particular patterns of emission lines. We often call them a chemical fingerprint because it really is like a particular fingerprint of particular elements in the gas in a galaxy.” </p>
<p>The universe started with just hydrogen and helium, but as stars formed and fused elements together, bigger, heavier elements started to emerge and fill in the periodic table as it is today. And just like Kartaltepe, Trump is finding evidence that things were happening faster in the early universe than astronomers expected. “I would’ve guessed that the universe would have struggled to make the periodic table and build up things. But that’s not what we found. Instead, the universe seems to have proceeded pretty rapidly.”</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photos showing thousands of galaxies in a night sky." src="https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/501210/original/file-20221215-20-lvlbo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photo shows Webb’s first deep-field image, a long exposure of a small part of the sky revealing thousands of galaxies, many of which are too faint for even Hubble to detect.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/035/01G7DCWB7137MYJ05CSH1Q5Z1Z?news=true">NASA/STScI</a></span>
</figcaption>
</figure>
<p>The discoveries coming out of James Webb are already changing how astronomers think of the early universe and challenging much of the existing theory. But the truly exciting part is that we are just beginning to see what this telescope is capable of, as <a href="https://scholar.google.com/citations?user=npUHvbwAAAAJ&hl=en&oi=ao">Michael Brown</a>, an astronomer at Monash University, explains. </p>
<p>“I’ve been on science papers that have used literally just a couple of minutes of data,” Brown says. “The image quality is just so good that a couple of minutes can do amazing things.” But soon Webb will begin to do follow-up surveys, take deep-field images and stare at parts of the sky for days and even weeks. Over the coming months, years and decades, Webb is going to keep giving astronomers plenty to work on, and astronomers like Brown are excited. “There is just all this complexity there, and we are barely scratching the surface. This will be the stuff that people who are students now are going to devote their careers to. And it’s going to be marvelous.”</p>
<hr>
<p>This episode was produced by Katie Flood and Daniel Merino, with sound design by Eloise Stevens. It was written by Katie Flood and Daniel Merino. Mend Mariwany is the show’s executive producer. Our theme music is by Neeta Sarl. </p>
<p>You can find us on Twitter <a href="https://twitter.com/TC_Audio">@TC_Audio</a>, on Instagram at <a href="https://www.instagram.com/theconversationdotcom/">theconversationdotcom</a> or <a href="mailto:podcast@theconversation.com">via email</a>. You can also sign up to The Conversation’s <a href="https://theconversation.com/newsletter">free daily email here</a>. A transcript of this episode will be available soon. </p>
<p>Listen to “The Conversation Weekly” via any of the apps listed above, download it directly via our <a href="https://feeds.acast.com/public/shows/60087127b9687759d637bade">RSS feed</a>, or find out <a href="https://theconversation.com/how-to-listen-to-the-conversations-podcasts-154131">how else to listen here</a>.</p><img src="https://counter.theconversation.com/content/196649/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span> </span></em></p><p class="fine-print"><em><span>Jeyhan Kartaltepe receives funding from NASA and the National Science Foundation.</span></em></p><p class="fine-print"><em><span>Jonathan Trump receives funding from NASA and NSF. </span></em></p><p class="fine-print"><em><span>Michael J. I. Brown receives research funding from the Australian Research Council and Monash University.</span></em></p>
It has been one year since the launch of the James Webb Space Telescope and six months since the first pictures were released. Astronomers are already learning unexpected things about the early universe.
Daniel Merino, Associate Science Editor & Co-Host of The Conversation Weekly Podcast, The Conversation
Nehal El-Hadi, Science + Technology Editor & Co-Host of The Conversation Weekly Podcast, The Conversation
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/187656
2022-08-30T13:44:48Z
2022-08-30T13:44:48Z
We don’t know if dark matter exists. So why do astronomers keep looking?
<figure><img src="https://images.theconversation.com/files/476134/original/file-20220726-32571-v7qdc9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Spiral galaxies like M100, pictured here, may hold answers about the nature of dark matter.</span> <span class="attribution"><span class="source">NASA Spitzer Space Telescope/NASA/JPL-Caltech</span></span></figcaption></figure><p>Scientists know very little about the matter that makes up the galaxies in the Universe. About 20% of the matter in galaxies is visible or <a href="https://astronomy.swin.edu.au/cosmos/b/Baryonic+Matter">baryonic</a>: subatomic particles like protons, neutrons and electrons. The other 80%, referred to as “dark matter”, remains mysterious and unseen. </p>
<p>In fact, it may not exist at all. “Dark matter” is just a hypothesis. Physicists and astronomers may be chasing a phantom – but that doesn’t stop us from looking. Why? Because if dark matter isn’t real, then the behaviour of the stars, planets and galaxies makes little sense. </p>
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<p>Today dark matter – and its cousin, dark energy – are the main pillars of a cosmological model called Lambda Cold Dark Matter, or <a href="https://www.universetoday.com/tag/lambda-cdm/">Lambda-CDM</a>. This model stresses that dark matter affects baryonic matter only via gravity. It does not interact with the electromagnetic force, meaning that it does not absorb, reflect or emit light.</p>
<p>In a recent study, published in <a href="https://www.aanda.org/articles/aa/abs/2021/09/aa40532-21/aa40532-21.html">Astronomy and Astrophysics</a>, we provide further evidence to support the existence of dark matter halos around early galaxies (when the Universe was half of its current age). We also challenge some assumptions about it. This is a way to deepen our understanding of the Universe and its galaxies.</p>
<h2>Origins of the theory</h2>
<p>In the 1970s, astronomers Vera Rubin and Kent Ford unveiled <a href="https://www.space.com/vera-rubin.html">the theory of dark matter</a>. They weren’t just taking a shot in the dark: there had long been a debate about why stars, planets and galaxies behaved in certain ways. For instance, why aren’t stars and gases constantly flung far and wide into outer space? What sort of glue keeps galaxies intact, exerting a <a href="https://www.astro.princeton.edu/%7Eburrows/classes/250/dark_matter.html">gravitational effect</a> on everyday baryonic particles?</p>
<p>Scientists also wondered why objects far beyond the centre of a galaxy orbit at much the same speeds (or velocities) as objects closer to the centre. This flies in the face of <a href="https://www.britannica.com/science/Newtons-laws-of-motion">Newton’s law</a>, which suggests that stars and gas should be slowing down the further they are from a galaxy’s centre. The greater abundance of stars and gases near the core should provide the necessary gravitational force that speeds up the stars and gas. The more thinly distributed they are at the edges of the galaxy, the less the gravitational force – and so, stars and gas should slow down. But observations suggest that they don’t.</p>
<p>To account for these discrepancies, Rubin and Ford argued that every galaxy is engulfed by a large halo of dark matter, providing the unaccounted-for mass. Dark matter, they claimed, provides around 85% of the matter within any one galaxy. Its <a href="https://www.sciencedaily.com/releases/2022/02/220211102628.htm">dominant presence</a> throughout galaxies arises from the fact that the stars and hydrogen gas are moving as if governed by an invisible element.</p>
<p>Their theory hasn’t been universally embraced. Some scientists have argued that <a href="https://iopscience.iop.org/article/10.3847/1538-4357/abbb96">dark matter doesn’t exist</a>.</p>
<p>But we and many others agree with Rubin and Ford. Dark matter exists because it explains so much. As one writer <a href="https://www.science.org/content/article/explain-away-dark-matter-gravity-would-have-be-really-weird-cosmologists-say">put it</a>:</p>
<blockquote>
<p>many [physicists] would happily dismiss the idea – if it didn’t work so well.</p>
</blockquote>
<h2>Looking way back into the Universe</h2>
<p>For <a href="https://www.aanda.org/articles/aa/abs/2021/09/aa40532-21/aa40532-21.html">our new study</a> we observed about 260 spiral-shaped star-forming galaxies some seven billion light years away. This is essentially a glimpse into the past. It is estimated that these galaxies existed when the Universe was half its present age of around 13.8 billion years. They appear to us now as no more than light signals. Spiral galaxies, of which our Milky Way is one, are characterised by the distinctive coiled, spiral arms of stars and gas clouds.</p>
<p>Our aim was to observe and determine, and then compare, the distribution of mass in these distant spiral galaxies with more recent, nearer galaxies of more or less the same characteristics. </p>
<p>Some recent studies have suggested that the earlier star-forming galaxies appear to be <a href="https://www.mpg.de/11170451/early-galaxies-dark-matter">deficient in dark matter</a> when compared to more recent or local ones. This has led <a href="https://www.mpg.de/11170451/early-galaxies-dark-matter">some researchers</a> to assert that dark matter plays a much smaller role in early star systems than in today’s galaxies. Our findings refute this suggestion. </p>
<p>We were able to confirm that the earlier galaxies we studied have the trademark halos of dark matter that build up from the centre and maintain a constant density up to a certain radius. This is largely in keeping with the standard scenario of dark matter observed in the galaxies of the local Universe. A surprise finding, however, was that these halos are <a href="https://www.aanda.org/articles/aa/full_html/2022/03/aa41822-21/aa41822-21.html">much more compact</a> than those galaxies closer to our Milky Way. This suggests that distribution of dark matter within a galaxy expand slowly over time. But how is this process powered?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=236&fit=crop&dpr=1 600w, https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=236&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=236&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=297&fit=crop&dpr=1 754w, https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=297&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/481594/original/file-20220829-9177-u3jh7b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=297&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>Our conclusion is that this phenomenon illustrates a direct interaction between dark matter particles and the everyday baryonic particles. This alters the density of the halos – and in doing so, goes beyond just the textbook gravitational relationship.</p>
<p>These findings don’t provide all the answers to all or even a few of the questions that exist about dark matter. But it certainly narrows the long search for dark matter particles. </p>
<p>It also provides some direction to the identification of dark matter particles, based on what they are capable of. That, in turn, opens up the discussion to other theories of dark matter, such as warm dark matter, self-interacting dark matter, and ultra light dark matter. All of these are much more interactive than cold dark matter. </p>
<h2>A deeper look</h2>
<p>For those of us equally mesmerised and confounded by dark matter, there may well be a light at the end of the tunnel. New technology is helping us to better understand the Universe and its dynamics.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-explains-the-stunning-newly-released-first-images-186800">James Webb Space Telescope: An astronomer explains the stunning, newly released first images</a>
</strong>
</em>
</p>
<hr>
<p>Finding answers will mean peering ever deeper into the centre of these earlier and “younger” galaxies. The new James Webb Space Telescope, launched at the end of 2021 and now orbiting some 1,500,000 km beyond Earth’s orbit around the Sun, may help in this regard. </p>
<p>So, too, will the new <a href="https://www.newscientist.com/article/2327468-worlds-most-sensitive-dark-matter-detector-tested-for-the-first-time/">LUX-ZEPLIN</a> dark matter detector, <a href="https://www.space.com/dark-matter-most-sensitive-detector-first-results">touted as</a> the “world’s most sensitive dark matter detector” and located around 1.5km underground in the US.</p>
<p><em>Professor Paolo Salucci (SISSA, Italy) and Professor Glenn van de Ven (UniVie, Austria) co-authored this article.</em></p><img src="https://counter.theconversation.com/content/187656/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gauri Sharma receives funding from SARAO and NRF. She is affiliated with University of the Western Cape, South Africa, SISSA, IFPU and INFN Trieste (Italy)</span></em></p>
A comparison of star-forming galaxies suggests, surprisingly, that dark matter and visible matter do interact – taking us closer to understanding what keeps the galaxies together.
Gauri Sharma, SARAO Postdoctoral Fellow, University of the Western Cape
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/187915
2022-08-01T04:04:51Z
2022-08-01T04:04:51Z
Is the James Webb Space Telescope finding the furthest, oldest, youngest or first galaxies? An astronomer explains
<figure><img src="https://images.theconversation.com/files/476660/original/file-20220729-20-z3fsbn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">James Webb has peered into the distant Universe</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet">NASA</a></span></figcaption></figure><p>We’ve now seen the <a href="https://www.nasa.gov/webbfirstimages">first data from the James Webb Space Telescope</a>. It has observed the atmospheres of distant planets, groups of nearby galaxies, galaxy light bent by unseen dark matter, and clouds of gas and dust in stellar nurseries. </p>
<p>We have also seen headlines claiming Webb has found “<a href="https://www.newscientist.com/article/2329601-jwst-has-found-the-oldest-galaxy-we-have-ever-seen-in-the-universe/">the oldest galaxies we have ever seen</a>”, but what does that mean? </p>
<p>I’m a professional astronomer who <a href="https://ui.adsabs.harvard.edu/abs/2008ApJ...682..937B/abstract">studies old galaxies</a>, and even I find this a little puzzling.</p>
<h2>Looking far, looking back</h2>
<p>One of the key <a href="https://webb.nasa.gov/content/science/">science goals of Webb</a> is to peer back in time and observe the early Universe. Webb can do this because, like all telescopes, it is a time machine. </p>
<p>Light travels at 300,000 kilometres per second, so when we look at the Moon we are seeing it as it was a second ago. As the planets of our Solar System are millions or billions of kilometres away, we see them as they were minutes or hours ago. </p>
<p>Going further still, when we look at distant galaxies with telescopes we are often looking at light that has taken millions or billions of years to reach us. This means we are seeing these galaxies as they were millions or billions of years ago.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/when-you-look-up-how-far-back-in-time-do-you-see-101176">When you look up, how far back in time do you see?</a>
</strong>
</em>
</p>
<hr>
<h2>What has James Webb seen?</h2>
<p>The James Webb Space Telescope is able to see more distant galaxies than other telescopes, including the Hubble Space Telescope. </p>
<p>Like Hubble it is above the glowing and turbulent atmosphere of the Earth. However, whereas Hubble has a 2.3 metre mirror for focusing light, Webb has a vast 6.5 metre mirror formed from 18 hexagonal segments. Finally, Webb is optimised to detect infrared light, which is what we observe from the most distant galaxies as the expansion of the Universe has stretched ultraviolet and infrared light into the infrared. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="James Webb has a vast segmented mirror." src="https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476657/original/file-20220729-19-43296g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">James Webb has a vast segmented mirror that allows it to look into the distant past.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Among the first data obtained by Webb were infrared images looking towards a cluster of galaxies called <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet">SMACS 0723</a>. </p>
<p>The light from SMACS 0723 has taken 4.6 billion years to reach us, so we are seeing it as it was 4.6 billion years ago. That’s slightly older than the Sun and the Earth, which only formed 4.56 billion years ago.</p>
<p>In recent weeks, galaxies far beyond SMACS 0723 have gained attention. Webb has detected a number of galaxies in the direction of SMACS 0723 and <a href="https://ceers.github.io/index.html">other regions</a> that could be so distant their light has taken 13.5 billion years to reach us. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1551864183230177280"}"></div></p>
<p>I say “could” because more data will be needed to absolutely confirm their distances, but some of these galaxies are <a href="https://twitter.com/astrosteven/status/1551732076734455808">very compelling</a> candidates (others <a href="https://twitter.com/stewilkins/status/1552334303383650304">less so</a>).</p>
<p>As the light has taken 13.5 billion years to reach us, we are seeing these galaxies as they were 13.5 billion years ago. The Universe itself is 13.8 billion years old, so we could be seeing galaxies as they were just a few hundred million years after the <a href="https://theconversation.com/au/topics/big-bang-470">Big Bang</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Maise's galaxy" src="https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=292&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=292&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=292&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=367&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=367&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476667/original/file-20220729-25-960hmj.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=367&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Maisie’s Galaxy may be one of the most distant celestial objects yet observed.</span>
<span class="attribution"><span class="source">Steve Finkelstein/Twitter</span></span>
</figcaption>
</figure>
<h2>Young, old or early?</h2>
<p>While these very distant galaxies have been advertised as the “<a href="https://www.dailymail.co.uk/sciencetech/article-11032541/James-Webb-discovers-oldest-galaxy-universe-13-5-billion-year-old-stars.html">oldest galaxies</a>”, I find this a little confusing. We are actually seeing these galaxies as they appeared when they were very young, perhaps a hundred million years old or so.</p>
<p>It is true that these galaxies will be old now, but our own Milky Way galaxy is very old now too. While our Sun is 4.56 billion years old, many stars in our galaxy are 10 billion years old and some stars in the Milky Way are <a href="https://www.anu.edu.au/news/all-news/oldest-stars-found-near-milky-way-centre">13 billion years old</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Milky Way is billions of years old." src="https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/476663/original/file-20220729-12-jfj12d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The galaxy we live in, the Milky Way, is billions of years old.</span>
<span class="attribution"><span class="source">Caroline Jones/Flickr</span></span>
</figcaption>
</figure>
<p>Furthermore, the very distant galaxies Webb has spotted will look very different today. Galaxies grow by acquiring gas and dark matter, forming new stars and merging with other galaxies. </p>
<p>A small galaxy that was vigorously forming stars soon after the Big Bang may have ended up being the seed of a galaxy that today is very massive and stopped forming stars long ago. That small galaxy and its old stars could also have ended up being just part of a larger galaxy formed relatively recently by merging galaxies together.</p>
<h2>A record set to fall</h2>
<p>So should we call these most distant galaxies young or old? Perhaps neither. </p>
<p>James Webb is seeing the <em>earliest</em> galaxies yet observed – some of the <em>first</em> galaxies that formed soon after the Big Bang.</p>
<p>I have thrown in one last caveat – “yet observed”. Webb has only just begun its <a href="https://webb.nasa.gov/content/about/faqs/facts.html">mission</a>, and current analyses are based on data collected over hours. </p>
<p>With days’ worth of data, Webb will push its view out to fainter and further objects, and see yet-more-distant galaxies. The record for the most distant and thus earliest observed galaxy will probably tumble a few times before the year is out.</p><img src="https://counter.theconversation.com/content/187915/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael J. I. Brown receives research funding from the Australian Research Council and Monash University.
</span></em></p>
James Webb has spotted extremely distant galaxies formed soon after the Big Bang, but are they old or young? Or is this the wrong question to ask?
Michael J. I. Brown, Associate Professor in Astronomy, Monash University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/186818
2022-07-13T20:01:49Z
2022-07-13T20:01:49Z
How the James Webb deep field images reminded me the divide between science and art is artificial
<figure><img src="https://images.theconversation.com/files/473735/original/file-20220713-24-ecd3xg.png?ixlib=rb-1.1.0&rect=0%2C0%2C2000%2C1152&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA/STScI</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The first task I give photography students is to create a starscape. </p>
<p>To do this, I ask them to sweep the floor beneath them, collect the dust and dirt in a paper bag and then sprinkle it onto a sheet of 8x10 inch photo paper. Then, using the photographic enlarger, expose the detritus-covered paper to light. After removing the dust and dirt, the paper is submerged in a bath of chemical developer. </p>
<p>In less than two minutes, an image slowly emerges of a universe teeming with galaxies. </p>
<p>I love it when the darkroom fills with the sound of their astonishment the moment they realise the dust beneath their feet is transformed into a scene of scientific wonder.</p>
<p>I was reminded of this analogue exercise when NASA’s James Webb Space Telescope shared the <a href="https://theconversation.com/two-experts-break-down-the-james-webb-space-telescopess-first-images-and-explain-what-weve-already-learnt-186738">first deep field images</a>. The public expression of wonder is not unlike that of my students in the darkroom. </p>
<p>But unlike our makeshift starscapes, the Deep Field images capture an actual galaxy cluster, “the deepest, the sharpest infrared view of the universe to date.” </p>
<p>This imaging precision will help scientists to solve the mysteries in our solar system and our place in it. </p>
<p>But they will also inspire continued experiments by artists who address the subject of space, the universe and our fragile place in it. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/two-experts-break-down-the-james-webb-space-telescopes-first-images-and-explain-what-weve-already-learnt-186738">Two experts break down the James Webb Space Telescope's first images, and explain what we've already learnt</a>
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</em>
</p>
<hr>
<h2>Creating art of space</h2>
<p>Images of the cosmos afford considerable visual pleasure. I listen to scientists passionately describing the information stored in their saturated colours and amorphous shapes, what the luminosity and shadows are, and what lurks in the deep blacks that are spotted and speckled. </p>
<p>The mysteries of the universe are the stuff of science and of the imagination. </p>
<p>Throughout history, artists have imagined and created proxy universes: constructions that are lyrical and speculative, alternate worlds that are stand-ins for what we imagine, hope and fear is “out there”. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A group of five galaxies that appear close to each other in the sky" src="https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=723&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=723&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473736/original/file-20220713-22-f9vc3b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=723&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The James Webb Space Telescope’s image of Stephan’s Quintet.</span>
<span class="attribution"><span class="source">NASA/STScI</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>There are the photo-real drawings and paintings of <a href="https://www.tate.org.uk/art/artworks/celmins-night-sky-19-ar00163">Vija Celmins</a>. The night sky painstakingly drawn or painted by hand with extraordinary detail and precision. </p>
<p>There is David Stephenson’s <a href="https://fstoppers.com/fine-art/david-stephensons-long-exposure-star-paths-3382">time lapse photographs</a> that read as lyrical celestial drawings reminding us that we are on a moving planet. Yosuke Takeda’s ambiguous <a href="https://www.artbasel.com/catalog/artwork/80779/Yosuke-Takeda-021019">star bursts</a> of colour and light. Thomas Ruff’s sensuous <a href="https://publicdelivery.org/thomas-ruff-stars/">star photos</a> made through the close cropping of the details of existing science images he bought after failing to be able to capture the cosmos with his own camera. </p>
<p>There’s also the incredible work of the Blue Mountains based duo <a href="https://pica.org.au/whats-on/energies-haines-hinterding/">Haines & Hinterding</a> where polka dots become stars, black pigment is the night sky, bleeding coloured ink is a gas formation. They make rocks hum and harness the sun’s rays so we can hear and smell its energy. </p>
<p>These artworks highlight the creative drive to draw on science for the purposes of art. The divide between science and art is an artificial one. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-making-a-film-exploring-indigenous-stories-of-the-night-sky-enriched-my-perspective-as-a-scientist-167529">How making a film exploring Indigenous stories of the night sky enriched my perspective as a scientist</a>
</strong>
</em>
</p>
<hr>
<h2>Pictures of our imaginations</h2>
<p>The Webb telescope shows science’s capacity to bring us images that are aesthetically imaginative, expressive and technically accomplished but – strangely – they don’t make me feel anything. </p>
<p>Science tells me these shapes are galaxies and stars billions of years away, but it isn’t sinking in. Instead, I see a fabulously constructed landscape like James Nasmyth’s famous <a href="https://special-collections.wp.st-andrews.ac.uk/2019/07/19/james-nasmyths-moon-images-1874/">moon images from 1874</a>. </p>
<p>In my imagination, I picture the Webb images as made of fairy lights, coloured gels, mirrors, black cloth, filters and photoshop. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=559&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=559&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=559&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=702&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=702&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473733/original/file-20220713-16-xnnw7j.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=702&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A planetary nebula, seen by the Webb telescope.</span>
<span class="attribution"><span class="source">NASA/STScI</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Art’s stand-ins invade my psyche. When I look at the deep field and planetary nebula, I remember that even these “objective” machine made images <a href="https://www.vox.com/2019/8/1/20750228/scientists-colorize-photos-space-hubble-telescope">are constructed</a>. The rays of light, holes and gases are artistic experiments in photographic abstraction, examining what lies beyond vision. </p>
<p>Imaging technology always transforms what is “out there”, and how we see it is determined by what is “in here”: our own subjectivity; what we bring of ourselves and our lives to the reading of the image. </p>
<p>The telescope is a photographer crawling through the cosmos, making more of the unseen seen. Giving artists more references for appropriation, imagination and also critique.</p>
<p>While scientists see structure and detail, artists see aesthetic and performative possibilities for asking pressing questions that concern the politics of space and place. </p>
<h2>Art in space</h2>
<p>Webb’s images present a renewed opportunity to reflect on the work of American artist Trevor Paglen, who sent the world’s <a href="https://news.artnet.com/art-world/trevor-paglen-orbital-reflector-lost-space-1533073">first artwork into space</a>. </p>
<p>Paglen’s work examines the political geography that is space and the ways in which governments aided by science use space for mass surveillance and data collection.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The background of space is black. Thousands of galaxies appear all across the view" src="https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473737/original/file-20220713-22-gmmupn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The deepest and sharpest infrared image of the early universe ever taken.</span>
<span class="attribution"><span class="source">NASA/STScI</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>He created a 30 metre diamond-shaped balloon called the Orbital Reflector, that was supposed to open up into an enormous reflective balloon and be seen from Earth as a bright star. It was rocketed into space on a satellite, but the engineers could not complete the sculpture’s deployment due the unexpected government shutdown. </p>
<p>Paglen’s artwork was <a href="https://news.artnet.com/art-world/trevor-paglen-responds-to-angry-astronomers-1337462">criticised</a> by scientists. </p>
<p>Unlike astronomers, he wasn’t trying to unlock the mystery of the universe or our place in it. He was asking: is space a place for art? Who owns space, and who is space for? </p>
<p>Space is readily available to government, military, commercial and scientific interests. For the time being, Earth remains the place for art.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/james-webb-telescope-a-scientist-explains-what-its-first-amazing-images-show-and-how-it-will-change-astronomy-186668">James Webb telescope: a scientist explains what its first, amazing images show – and how it will change astronomy</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/186818/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cherine Fahd does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Long before the James Webb telescope brought us these deep field images, artists have been capturing notions of space.
Cherine Fahd, Associate Professor of Visual Communication in the School of Design, University of Technology Sydney
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/186800
2022-07-13T00:01:03Z
2022-07-13T00:01:03Z
James Webb Space Telescope: An astronomer explains the stunning, newly released first images
<figure><img src="https://images.theconversation.com/files/473703/original/file-20220712-12-aekfeq.png?ixlib=rb-1.1.0&rect=0%2C134%2C1880%2C1368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">This cluster of galaxies, called Stephan's Quintet, is a composite image produced from two cameras aboard the James Webb Space Telescope.</span> <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/034/01G7DA5ADA2WDSK1JJPQ0PTG4A?news=true">NASA/STScI</a></span></figcaption></figure><p>The James Webb Space Telescope team has <a href="https://www.nasa.gov/webbfirstimages">released the first science-quality images</a> from the new telescope. In them are the oldest galaxies ever seen by human eyes, evidence of water on a planet 1,000 light-years away and incredible details showing the birth and death of stars. Webb’s purpose is to explore origins – of the universe, of galaxies, of stars and of life – and the five images released on July 12, 2022, make good on that promise. </p>
<p>Once the suite of instruments onboard all <a href="https://theconversation.com/the-james-webb-space-telescope-is-finally-ready-to-do-science-and-its-seeing-the-universe-more-clearly-than-even-its-own-engineers-hoped-for-184989">cooled down and were running smoothly</a>, astronomers wasted no time in putting Webb to work. Each of the first images contains enough data to produce major scientific results on their own. </p>
<p>Webb was designed to <a href="https://theconversation.com/the-most-powerful-space-telescope-ever-built-will-look-back-in-time-to-the-dark-ages-of-the-universe-169603">collect light across the entire red to mid-infrared spectrum</a> – wavelengths of light that are blocked by Earth’s atmosphere. And with its giant mirror and sun-shade blocking infrared emitted by the Sun, Earth and Moon, Webb can produce images of a sharpness never before achieved by any other telescope. </p>
<p>The buzz among <a href="https://www.uml.edu/Sciences/physics/faculty/Laycock-Silas.aspx">professional astronomers like me</a> has been electric since members of the Webb team shared tantalizing test images. And the real images are even better than anyone could have hoped for. During the presentation where the first images were released, Webb <a href="https://www.nasa.gov/content/first-images-from-the-james-webb-space-telescope">project scientist Jane Rigby remarked</a> “for Webb there is no blank sky, everywhere it looks it sees distant galaxies.” Most of those galaxies were invisible until now.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing thousands of galaxies in a night sky." src="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473704/original/file-20220712-12-qk9b76.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This photo shows gravitational lensing and many bright galaxies, but the smaller, fainter, less distinct galaxies in this image are some of the oldest light ever detected by a human-made object.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/035/01G7DCWB7137MYJ05CSH1Q5Z1Z?news=true">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Ancient galaxies and the early universe</h2>
<p>The first Webb image the world saw is of a galaxy cluster known to astronomers as <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet">SMACS 0723</a>. It lies in the southern hemisphere sky and is 5.12 billion light-years from Earth. </p>
<p>The detail of the thousands of individual galaxies in the image is stunning. It is like the universe in high definition, and I encourage you to look at the <a href="https://stsci-opo.org/STScI-01G7JJADTH90FR98AKKJFKSS0B.png">full resolution image</a> and zoom in to truly appreciate the details. </p>
<p>The large white galaxies in the middle of the image belong to the cluster and are similar in age to the Sun and Earth. Surrounding and interspersed among the cluster galaxies are more distant galaxies, but stretched into spectacular arcs as if seen through a magnifying glass. And that is exactly what is happening. The background galaxies are much farther from Earth but appear magnified, as their light is bent toward Earth by the gravity of the much closer cluster. </p>
<p>In the background you can see faint red galaxies scattered like rubies across the sky. Those galaxies are even farther away. By measuring precise attributes of their light, astronomers can tell that they formed over 13 billion years ago and even determine the abundance of different elements in these early galaxies. </p>
<p>Webb is not only producing incredibly sharp images, but it is doing so easily when compared to its predecessor, the Hubble Space Telescope, which was launched in 1990. As Rigby quipped, “… the Hubble Extremely Deep Field took two weeks of exposure, Webb went deeper before breakfast.” Once Webb carries out longer observations that allow it to collect more light from faint stars or galaxies, astronomers will be able to see some of the first stars and galaxies that formed right after the Big Bang. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A chart showing peaks and valleys of light at different wavelengths." src="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473706/original/file-20220712-9214-uyqbas.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The James Webb Space Telescope is sensitive enough to not only detect light that passes though the atmospheres of distant planets, but to measure the strength of this light at different wavelengths – as shown here – which can suggest the presence of water or other molecules in an atmosphere.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2022/032/01G72VSFW756JW5SXWV1HYMQK4?news=true">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Understanding planets around other stars</h2>
<p>The second reveal was not of an image but a spectrum – a breakdown of the strength of light at different wavelengths. </p>
<p>Webb pointed its mirror at the <a href="https://theconversation.com/accelerating-exoplanet-discovery-using-chemical-signatures-of-stars-118818">exoplanet</a> WASP 96-B – a giant hot gas planet orbiting a star about 1,000 light-years from Earth – as the planet passed in front of its parent star. During this transit, a portion of the star’s light was filtered through the planet’s atmosphere and left a “chemical fingerprint” in the light’s unique spectrum. The specifics of this fingerprint strongly suggest that there is water vapor, clouds and haze in the atmosphere of WASP 96-B. </p>
<p>As Webb moves on to observe <a href="https://theconversation.com/an-earth-sized-planet-found-in-the-habitable-zone-of-a-nearby-star-129290">smaller planets that could potentially harbor life</a>, astronomers expect to detect the fingerprints of oxygen, nitrogen, ammonia and carbon in the form of methane and other hydrocarbons. The goal is to find biosignatures of life – that is, chemistry that would point toward the atmosphere being modified by living organisms. </p>
<p>The technical challenge of doing this type of observation, called transit spectroscopy, is enormous, and this initial result barely scratches the surface of the scientific content of the spectrum.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A giant hazy cloud of gas and dust with points of light within." src="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473711/original/file-20220712-31570-vot4hk.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fine details seen in this image of the Carina Nebula offer clues to how stars are born.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth">NASA/STScI</a></span>
</figcaption>
</figure>
<h2>Galactic dances and the lives of stars</h2>
<p>The last three images showed the incredible resolution of Webb’s optics as the telescope explored the birth and death of stars. </p>
<p>Webb’s ability to capture light in the mid-infrared range allows its cameras to cut through dense clouds of dust and gas. This ability helped Webb to capture <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-reveals-cosmic-cliffs-glittering-landscape-of-star-birth">spectacular details of the Carina Nebula</a> where stars are born.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two side-by-side images of a round cloud of gas around a bright star." src="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473705/original/file-20220712-26-cqe66p.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=350&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Webb telescope can take high resolution images using multiple cameras with each revealing different details, as demonstrated in these side-by-side photos of a dying star.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-captures-dying-star-s-final-performance-in-fine-detail">NASA/STScI</a></span>
</figcaption>
</figure>
<p>Webb is also excellently suited to study the end of a star’s life. As stars get old, they can puff off their outer layers and form nebulas like the stunning <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-captures-dying-star-s-final-performance-in-fine-detail">Southern Ring Nebula, which was imaged by Webb</a>. The image revealed never-before-seen details of successive waves of matter expelled by the dying central star. While Hubble was unable to see through the expanding cloud of dust and debris, Webb provided the first look at the binary star system that formed the nebula.</p>
<p>The last photo from Webb’s coming out party <a href="https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-sheds-light-on-galaxy-evolution-black-holes">showed Stephan’s Quintet</a>, a group of five galaxies 300 million light-years from Earth, interacting in a cosmic dance. Thanks to the suite of complementary instruments aboard Webb, the telescope can simultaneously pick up details of individual stars in these galaxies, see the cold dust and gas fueling star formation within these galaxies and – most remarkably – block out the stars, gas and dust to see the material swirling around the supermassive black hole at the center of one of the galaxies. </p>
<p>Webb also captured data on the spectra of hundreds of individual star-forming regions in the Quintet, which will take months to analyze and study.</p>
<p>Webb is the result of 25 years of work by thousands of scientists, engineers and administrators belonging to an international collaboration of space agencies, companies, research centers and universities worldwide. John Mather, a project leader for Webb, <a href="https://www.nasa.gov/content/first-images-from-the-james-webb-space-telescope">emotionally described the journey</a>: “This was hard to do. It is difficult to express just how hard this was. There were so many thousands of ways it could have gone wrong.”</p>
<p>But it didn’t go wrong. It all came together, and now humanity’s greatest space telescope is open for business.</p>
<p><em>This story was updated to correct the description of the photo of the Southern Ring Nebula.</em></p><img src="https://counter.theconversation.com/content/186800/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Silas Laycock works at The University of Massachusetts Lowell. He receives funding from NASA and the NSF. He is affiliated with the American Astronomical Society, and the Lowell Center for Space Science and Technology.</span></em></p>
NASA released five new images from the James Webb Space Telescope, revealing incredible details of ancient galaxies, stars and the presence of water in the atmosphere of a distant planet.
Silas Laycock, Professor of Astronomy, UMass Lowell
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/186668
2022-07-12T16:15:46Z
2022-07-12T16:15:46Z
James Webb telescope: a scientist explains what its first, amazing images show – and how it will change astronomy
<figure><img src="https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&rect=0%2C32%2C3573%2C2010&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A star forming region in the Milky Way.</span> <span class="attribution"><span class="source"> NASA, ESA, CSA, and STScI</span></span></figcaption></figure><p>After decades of development and many trials and frustrations along the way, the <a href="https://theconversation.com/how-hubbles-successor-will-give-us-a-glimpse-into-the-very-first-galaxies-45970">James Webb telescope</a> has finally started to deliver what it came for. On July 12, Nasa released the first scientific observations made by the suite of instruments carried on board the mission, marking what we eagerly anticipate will be the <a href="https://theconversation.com/james-webb-telescope-how-it-could-uncover-some-of-the-universes-best-kept-secrets-173717">beginning of a new era in astronomy</a>.</p>
<p>After the <a href="https://theconversation.com/james-webb-space-telescope-how-our-launch-of-worlds-most-complex-observatory-will-rest-on-a-nail-biting-knife-edge-173619">nail-biting launch</a> on Christmas Day, a series of critical deployments followed to open up the telescope and its sun-shade. If any of these operations had failed, James Webb would have been an unusable disaster. But the programme was perfectly executed, a process that ran more smoothly and successfully than any one of us had dared hope, let alone expect. </p>
<p>This is not just a testament to the skill of the engineers, technicians and scientists in the project. It also highlights the tremendous importance of the testing programme carried out on Earth to verify the procedures and which occasionally revealed problems that needed to be fixed before launch. While this sometimes resulted in schedule slippages and cost increases, it has ultimately produced a perfect telescope.</p>
<p>During July, the telescope moved from its checkout and testing phase to operation, as the amazing observatory it has long been planned to be. Those of us who have been involved in the journey and will work on the data, can hardly wait. </p>
<h2>Crisp images</h2>
<p>The new “early release observations”, selected by an international committee of representatives from Nasa, Esa (European Space Agency), CSA (Canadian Space Agency), and the Space Telescope Science Institute, are part of a programme designed to highlight the wide range of science the telescope will carry out.</p>
<p>It is very exciting to see the new images – I was not prepared for the level of crispness and fine detail that can be seen. It’s a joy to finally have such high-quality data.</p>
<p>Unveiled by US president Joe Biden, the stunning image of <a href="https://esawebb.org/images/webb-first-deep-field/">SMACS 0723</a>, a cluster of thousands of galaxies, was released on July 11. The massive foreground galaxy groups magnify and distort the light of objects behind them, helping us to peer back in time at very faint objects. </p>
<p>The image shows the galaxy cluster as it appeared 4.6 billion years ago. But more distant galaxies in the image (the ones which appear stretched) are about 13 billion years old – and we already have more data on them than we have on any other ancient galaxy.</p>
<p>Images such as this will help us understand how the first stars and galaxies formed. Some of these may be among the most distant objects known, from the beginning of the universe. The picture is a composite “colour” image made from observations made at different wavelengths. It was taken by the telescope’s Near-Infrared Camera (NIRCam). </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of SMACS 0723." src="https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=612&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=612&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=612&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=769&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=769&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473574/original/file-20220712-16-pndrc3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=769&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">SMACS 0723.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>James Webb has also caught a glimpse of <a href="https://www.nasa.gov/mission_pages/hubble/multimedia/ero/ero_stephan_quintet.html">Stephan’s Quintet</a>, a group of five galaxies that are merging some 290 million light-years away in the constellation Pegasus. The image also suggests there’s a supermassive black hole at the centre, and shows stars being born. The data will tell us more about how galaxies evolve and the rate at which supermassive black holes grow. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of Stephan's Quintet." src="https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=723&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=723&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473658/original/file-20220712-16-vorzg4.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=723&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stephen’s quintet.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The next picture shows the <a href="https://hubblesite.org/contents/media/images/2007/16/2099-Image.html">Carina Nebula</a>, seen in the image below, which is one of the largest and brightest nebulas (clouds of dust and gas in which stars are born). James Webb can probe deep inside dust in the infrared light, to reveal the inside of the stellar nursery – which we’ve never seen before – to discover more about how stars are born. </p>
<p>The Carina Nebula is located approximately 7,600 light-years away in the southern constellation Carina. The image shows hundreds of completely new stars (every dot of light is a star), and jets and bubbles created by them. We can also see details that we cannot yet explain.</p>
<figure class="align-center ">
<img alt="Image of the Carina nebula." src="https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&rect=0%2C32%2C3573%2C2010&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=348&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=348&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=348&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=437&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=437&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473660/original/file-20220712-14-qv200v.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=437&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A star-forming region in the Milky Way.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The next, spectacular image is of the <a href="https://www.nasa.gov/multimedia/imagegallery/image_feature_443.html">Southern Ring</a> or “Eight-Burst” nebula, a planetary nebula, which is an expanding cloud of gas, surrounding a dying star, or in this case two dying stars orbiting each other. It is nearly half a light-year in diameter and is located approximately 2,000 light years away from Earth. </p>
<p>The foamy orange shell in the image is molecular hydrogen (a gas which forms when two hydrogen atoms bond together), whereas the blue centre is an electrically charged gas. In the right-hand image, you can see the two dying stars in the centre, giving us an opportunity to study stellar death in unprecedented detail.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of the Southern Ring Nebula." src="https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=278&fit=crop&dpr=1 600w, https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=278&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=278&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=350&fit=crop&dpr=1 754w, https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=350&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/473655/original/file-20220712-31833-jg3tta.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=350&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Southern Ring Nebula.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, and STScI</span></span>
</figcaption>
</figure>
<p>The new data is the result of months of painstaking measurement and testing to make the James Webb ready for use as a scientific tool following deployment. The first steps were to focus and align the images of each of the mirror segments. Each of the telescope’s scientific instruments - NIRCam, <a href="https://www.jwst.nasa.gov/content/observatory/instruments/nirspec.html">The Near InfraRed Spectrograph</a> (NIRSpec) and <a href="https://webb.nasa.gov/content/observatory/instruments/miri.html">Mid-Infrared Instrument</a> (MIRI) – were also switched on and tested. </p>
<p>All these instruments, which look at deep space in different wavelengths, had to be cooled down, along with the telescope, otherwise they would radiate background heat which would interfere with the sensitive observations of astronomical objects. The last to be turned on was MIRI, which operates at the lowest temperature, just seven degrees above absolute zero, which took several months to achieve.</p>
<p>The size of a telescope – its aperture – is the key thing that decides the ultimate quality of the images and the detail that can be observed. Bigger is better. Large telescopes with apertures up to ten metres in diameter have been constructed on the ground. </p>
<p>However, the interfering effects of the atmosphere, which disturb the light reaching the telescope, make it hard to achieve the ultimate resolution. Also, on Earth, background light from the night sky limits the telescope sensitivity, the faintest objects we can see.</p>
<p>With its six-metre aperture, James Webb is the largest telescope ever launched into space and from its vantage point a million miles from Earth, free from the Earth’s atmosphere, it is expected to deliver the best, most detailed views of the universe we have ever seen. There is no doubt that it will revolutionise our understanding of the cosmos, just as its predecessor, the Hubble Space Telescope, once did.</p><img src="https://counter.theconversation.com/content/186668/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Barstow receives funding from Uk Space Agency. </span></em></p>
Even experts were not prepared for the crispness of the new images from the James Webb space telescope.
Martin Barstow, Professor of Astrophysics and Space Science, University of Leicester
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/186344
2022-07-07T16:47:33Z
2022-07-07T16:47:33Z
Dark matter: our review suggests it’s time to ditch it in favour of a new theory of gravity
<figure><img src="https://images.theconversation.com/files/472844/original/file-20220706-25-fxgof1.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1022%2C873&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The barred spiral galaxy UGC 12158.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Barred_spiral_galaxy#/media/File:UGC_12158.jpg">Wikimedia </a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>We can model the motions of planets in the Solar System quite accurately using Newton’s laws of physics. But in the early 1970s, scientists noticed that <a href="https://www.sciencedirect.com/topics/physics-and-astronomy/disk-galaxies">this didn’t work for</a> <a href="https://astronomy.swin.edu.au/cosmos/d/Disk+Galaxies">disc galaxies</a> – stars at their outer edges, far from the gravitational force of all the matter at their centre – were moving much faster than Newton’s theory predicted. </p>
<p>This made physicists propose that an invisible substance called “dark matter” was providing extra gravitational pull, causing the stars to speed up – a theory that’s become hugely popular. However, in a <a href="https://www.mdpi.com/2073-8994/14/7/1331">recent review</a> my colleagues and I suggest that observations across a vast range of scales are much better explained in an alternative theory of gravity proposed by Israeli physicist Mordehai Milgrom in 1982 called Milgromian dynamics or <a href="https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics">Mond</a> – requiring no invisible matter.</p>
<p>Mond’s main postulate is that when gravity becomes very weak, as occurs at the edge of galaxies, it starts behaving differently from Newtonian physics. In this way, it is possible to <a href="https://doi.org/10.1051/0004-6361/201732547">explain</a> why stars, planets and gas in the outskirts of over 150 galaxies rotate faster than expected based on just their visible mass. But Mond doesn’t merely <em>explain</em> such rotation curves, in many cases, it <em>predicts</em> them.</p>
<p>Philosophers of science <a href="https://www.cambridge.org/core/books/philosophical-approach-to-mond/9E770E2F021E79EE639C9A750143C589">have argued</a> that this power of prediction makes Mond superior to the standard cosmological model, which proposes there is more dark matter in the universe than visible matter. This is because, according to this model, galaxies have a highly uncertain amount of dark matter that depends on details of how the galaxy formed – which we don’t always know. This makes it impossible to predict how quickly galaxies should rotate. But such predictions are routinely made with Mond, and so far these have been confirmed.</p>
<p>Imagine that we know the distribution of visible mass in a galaxy but do not yet know its rotation speed. In the standard cosmological model, it would only be possible to say with some confidence that the rotation speed will come out between 100km/s and 300km/s on the outskirts. Mond makes a more definite prediction that the rotation speed must be in the range 180-190km/s.</p>
<p>If observations later reveal a rotation speed of 188km/s, then this is consistent with both theories – but clearly, Mond is preferred. This is a modern version of <a href="https://en.wikipedia.org/wiki/Occam%27s_razor">Occam’s razor</a> – that the simplest solution is preferable to more complex ones, in this case that we should explain observations with as few “free parameters” as possible. Free parameters are constants - certain numbers that we must plug into equations to make them work. But they are not given by the theory itself – there’s no reason they should have any particular value – so we have to measure them observationally. An example is the gravitation constant, G, in Newton’s gravity theory or the amount of dark matter in galaxies within the standard cosmological model.</p>
<p>We introduced a concept known as “theoretical flexibility” to capture the underlying idea of Occam’s razor that a theory with more free parameters is consistent with a wider range of data – making it more complex. In our review, we used this concept when testing the standard cosmological model and Mond against various astronomical observations, such as the rotation of galaxies and the motions within galaxy clusters.</p>
<p>Each time, we gave a theoretical flexibility score between –2 and +2. A score of –2 indicates that a model makes a clear, precise prediction without peeking at the data. Conversely, +2 implies “anything goes” – theorists would have been able to fit almost any plausible observational result (because there are so many free parameters). We also rated how well each model matches the observations, with +2 indicating excellent agreement and –2 reserved for observations that clearly show the theory is wrong. We then subtract the theoretical flexibility score from that for the agreement with observations, since matching the data well is good – but being able to fit anything is bad.</p>
<p>A good theory would make clear predictions which are later confirmed, ideally getting a combined score of +4 in many different tests (+2 -(-2) = +4). A bad theory would get a score between 0 and -4 (-2 -(+2)= -4). Precise predictions would fail in this case – these are unlikely to work with the wrong physics.</p>
<p>We found an average score for the standard cosmological model of –0.25 across 32 tests, while Mond achieved an average of +1.69 across 29 tests. The scores for each theory in many different tests are shown in figures 1 and 2 below for the standard cosmological model and Mond, respectively.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Comparing the standard cosmological model with observations" src="https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=502&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=502&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=502&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=631&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=631&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472829/original/file-20220706-4568-wcqncw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=631&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Comparison of the standard cosmological model with observations based on how well the data matches the theory (improving bottom to top) and how much flexibility it had in the fit (rising left to right). The hollow circle is not counted in our assessment, as that data was used to set free parameters. Reproduced from table 3 of our review.</span>
<span class="attribution"><span class="source">Arxiv</span></span>
</figcaption>
</figure>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Comparing MOND with observations" src="https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=361&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=361&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=361&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=454&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=454&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472828/original/file-20220706-14-a9kfqm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=454&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Similar to Figure 1, but for Mond with hypothetical particles that only interact via gravity called sterile neutrinos. Notice the lack of clear falsifications. Reproduced from Table 4 of our review.</span>
<span class="attribution"><span class="source">Arxiv</span></span>
</figcaption>
</figure>
<p>It is immediately apparent that no major problems were identified for Mond, which at least plausibly agrees with all the data (notice that the bottom two rows denoting falsifications are blank in figure 2).</p>
<h2>The problems with dark matter</h2>
<p>One of the most striking failures of the standard cosmological model relates to “galaxy bars” – rod-shaped bright regions made of stars – that spiral galaxies often have in their central regions (see lead image). The bars rotate over time. If galaxies were embedded in massive halos of dark matter, their bars would slow down. However, most, if not all, observed galaxy bars are fast. This <a href="https://astrobites.org/2022/06/04/the-standard-model-fails-to-pass-the-bar/">falsifies</a> the standard cosmological model with very high confidence.</p>
<p>Another problem is that the <a href="https://ui.adsabs.harvard.edu/abs/1973ApJ...186..467O">original models</a> that suggested galaxies have dark matter halos made a big mistake – they assumed that the dark matter particles provided gravity to the matter around it, but were not affected by the gravitational pull of the normal matter. This simplified the calculations, but it doesn’t reflect reality. When this was taken into account in <a href="https://doi.org/10.1093/mnras/stz1145">subsequent simulations</a> it was clear that dark matter halos around galaxies do not reliably explain their properties.</p>
<p>There are many other failures of the standard cosmological model that we investigated in our review, with Mond often able to <a href="https://doi.org/10.3847/1538-4357/abc623">naturally explain</a> the observations. The reason the standard cosmological model is nevertheless so popular could be down to computational mistakes or limited knowledge about its failures, some of which were discovered quite recently. It could also be due to people’s reluctance to tweak a gravity theory that has been so successful in many other areas of physics.</p>
<p>The huge lead of Mond over the standard cosmological model in our study led us to conclude that Mond is strongly favoured by the available observations. While we do not claim that Mond is perfect, we still think it gets the big picture correct – galaxies really do lack dark matter.</p><img src="https://counter.theconversation.com/content/186344/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Indranil Banik is paid from a grant awarded by the STFC whose primary objective is to test MOND using wide binary stars in the Solar neighbourhood.</span></em></p>
Recent results cast doubt on dark matter.
Indranil Banik, Postdoctoral Research Fellow of Astrophysics, University of St Andrews
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/184989
2022-06-15T12:26:32Z
2022-06-15T12:26:32Z
The James Webb Space Telescope is finally ready to do science – and it’s seeing the universe more clearly than even its own engineers hoped for
<figure><img src="https://images.theconversation.com/files/468846/original/file-20220614-21-gxm00d.jpg?ixlib=rb-1.1.0&rect=170%2C463%2C4769%2C2962&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The mirror on the James Webb Space Telescope is fully aligned and producing incredibly sharp images, like this test image of a star.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/51942047253/">NASA/STScI via Flickr</a></span></figcaption></figure><p><em>NASA is scheduled to release the first images taken by the James Webb Space Telescope on July 12, 2022. They’ll mark the beginning of the next era in astronomy as Webb – the largest space telescope ever built – begins collecting scientific data that will help answer questions about the earliest moments of the universe and allow astronomers to study exoplanets in greater detail than ever before. But it has taken nearly eight months of travel, setup, testing and calibration to make sure this most valuable of telescopes is ready for prime time. <a href="https://scholar.google.com/citations?user=WajSxxMAAAAJ&hl=en&oi=ao">Marcia Rieke, an astronomer at the University of Arizona</a> and the scientist in charge of one of Webb’s four cameras, explains what she and her colleagues have been doing to get this telescope up and running.</em> </p>
<h2>1. What’s happened since the telescope launched?</h2>
<p>After the successful launch of the James Webb Space Telescope on Dec. 25, 2021, the team began the long process of moving the telescope into its final orbital position, unfolding the telescope and – as everything cooled – calibrating the cameras and sensors onboard. </p>
<p>The launch went as smoothly as a rocket launch can go. One of the first things my colleagues at NASA noticed was that the telescope had more remaining fuel onboard than predicted to make future adjustments to its orbit. This will allow Webb to <a href="https://blogs.nasa.gov/webb/2021/12/29/nasa-says-webbs-excess-fuel-likely-to-extend-its-lifetime-expectations/">operate for much longer</a> than the mission’s initial 10-year goal.</p>
<p>The first task during Webb’s monthlong journey to its final location in orbit was to unfold the telescope. This went along without any hitches, starting with the <a href="https://www.nasa.gov/press-release/sunshield-successfully-deploys-on-nasa-s-next-flagship-telescope">white-knuckle deployment of the sun shield</a> that helps cool the telescope, followed by the alignment of the mirrors and the turning on of sensors.</p>
<p>Once the sun shield was open, our team began monitoring the temperatures of the <a href="https://theconversation.com/james-webb-space-telescope-an-astronomer-on-the-team-explains-how-to-send-a-giant-telescope-to-space-and-why-167516">four cameras and spectrometers onboard</a>, waiting for them to reach temperatures low enough so that we could start testing each of the <a href="https://blogs.nasa.gov/webb/2022/05/12/seventeen-modes-to-discovery-webbs-final-commissioning-activities/">17 different modes in which the instruments can operate</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A gold-plated complicated piece of technology sitting on a table." src="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=497&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=497&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468847/original/file-20220614-12-bdzy11.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=497&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The NIRCam on Webb was the first instrument to go online and helped align the 18 mirror segments.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:JWST_Nircam1lwres.jpg#/media/File:JWST_Nircam1lwres.jpg">NASA Goddard Space Center/Wikimedia Commons</a></span>
</figcaption>
</figure>
<h2>2. What did you test first?</h2>
<p>The cameras on Webb cooled just as the engineers predicted, and the first instrument the team turned on was the Near Infrared Camera – or NIRCam. NIRCam is designed to study the <a href="https://www.jwst.nasa.gov/content/observatory/instruments/nircam.html">faint infrared light produced by the oldest stars or galaxies</a> in the universe. But before it could do that, NIRCam had to help align the 18 individual segments of Webb’s mirror.</p>
<p>Once NIRCam cooled to minus 280 F, it was cold enough to start detecting light reflecting off of Webb’s mirror segments and produce the telescope’s first images. The NIRCam team was ecstatic when the first light image arrived. We were in business! </p>
<p>These images showed that the mirror segments were <a href="https://blogs.nasa.gov/webb/2022/02/11/photons-received-webb-sees-its-first-star-18-times/">all pointing at a relatively small area of the sky</a>, and the alignment was much better than the worst-case scenarios we had planned for.</p>
<p>Webb’s Fine Guidance Sensor also went into operation at this time. This sensor helps keep the telescope pointing steadily at a target – much like image stabilization in consumer digital cameras. Using the star HD84800 as a reference point, my colleagues on the NIRCam team helped dial in the alignment of the mirror segments until it was virtually perfect, <a href="https://www.nasa.gov/press-release/nasa-s-webb-reaches-alignment-milestone-optics-working-successfully">far better than the minimum required for a successful mission</a>.</p>
<h2>3. What sensors came alive next?</h2>
<p>As the mirror alignment wrapped up on March 11, the Near Infrared Spectrograph – NIRSpec – and the Near Infrared Imager and Slitless Spectrograph – NIRISS – finished cooling and joined the party.</p>
<p>NIRSpec is designed to measure the <a href="https://jwst.nasa.gov/content/observatory/instruments/nirspec.html">strength of different wavelengths of light</a> coming from a target. This information can reveal the composition and temperature of distant stars and galaxies. NIRSpec does this by looking at its target object through a slit that keeps other light out. </p>
<p>NIRSpec has multiple slits that allow it to <a href="https://jwst-docs.stsci.edu/jwst-near-infrared-spectrograph/nirspec-instrumentation/nirspec-fixed-slits">look at 100 objects at once</a>. Team members began by testing the multiple targets mode, commanding the slits to open and close, and they confirmed that the slits were responding correctly to commands. Future steps will measure exactly where the slits are pointing and check that <a href="https://www.stsci.edu/jwst/instrumentation/instruments#section-8bc155d1-1325-4c34-b2c0-c1bb6524cdbd">multiple targets can be observed simultaneously</a>. </p>
<p>NIRISS is a slitless spectrograph that will also break light into its different wavelengths, but it is better at <a href="https://blogs.nasa.gov/webb/2022/06/03/the-modes-of-webbs-niriss/">observing all the objects in a field, not just ones on slits</a>. It has several modes, including two that are designed specifically for studying exoplanets particularly close to their parent stars.</p>
<p>So far, the instrument checks and calibrations have been proceeding smoothly, and the results show that both NIRSpec and NIRISS will deliver even better data than engineers predicted before launch.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two images showing a tangled web of stars and dust but the one on the right is much sharper." src="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=458&fit=crop&dpr=1 600w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=458&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=458&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=575&fit=crop&dpr=1 754w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=575&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/468848/original/file-20220614-17290-p0op1u.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=575&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The MIRI camera, image on the right, allows astronomers to see through dust clouds with incredible sharpness compared with previous telescopes like the the Spitzer Space Telescope, which produced the image on the left.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/52061788279/in/album-72177720296737701/">NASA/JPL-Caltech (left), NASA/ESA/CSA/STScI (right)/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>4. What was the last instrument to turn on?</h2>
<p>The final instrument to boot up on Webb was the Mid-Infrared Instrument, or MIRI. MIRI is designed to take photos of distant or newly formed galaxies as well as faint, small objects like asteroids. This sensor detects the longest wavelengths of Webb’s instruments and must be kept at minus 449 F – just 11 degrees F above absolute zero. If it were any warmer, the detectors would pick up only the heat from the instrument itself, not the interesting objects out in space. MIRI has <a href="https://jwst.nasa.gov/content/about/innovations/cryocooler.html">its own cooling system</a>, which needed extra time to become fully operational before the instrument could be turned on.</p>
<p>Radio astronomers have found hints that there are galaxies completely <a href="http://www.sci-news.com/astronomy/alma-dust-obscured-galaxies-early-universe-10094.html">hidden by dust and undetectable by telescopes like Hubble</a> that captures wavelengths of light similar to those visible to the human eye. The extremely cold temperatures allow MIRI to be incredibly sensitive to light in the mid-infrared range which can pass through dust more easily. When this sensitivity is combined with Webb’s large mirror, it allows MIRI to <a href="https://blogs.nasa.gov/webb/2022/05/09/miris-sharper-view-hints-at-new-possibilities-for-science/">penetrate these dust clouds and reveal the stars and structures</a> in such galaxies for the first time. </p>
<h2>5. What’s next for Webb?</h2>
<p>As of June 15, 2022, all of Webb’s instruments are on and have taken their first images. Additionally, four imaging modes, three time series modes and three spectroscopic modes have been tested and certified, leaving just three to go.</p>
<p>On July 12, NASA plans to <a href="https://www.nasa.gov/feature/goddard/2022/first-images-from-nasa-s-webb-space-telescope-coming-soon">release a suite of teaser observations</a> that illustrate Webb’s capabilities. These will show the beauty of Webb imagery and also give astronomers a real taste of the quality of data they will receive.</p>
<p>After July 12, the James Webb Space Telescope will start working full time on its science mission. The detailed schedule for the coming year hasn’t yet been released, but astronomers across the world are eagerly waiting to get the first data back from the most powerful space telescope ever built.</p><img src="https://counter.theconversation.com/content/184989/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Marcia Rieke receives funding from NASA.</span></em></p>
It has taken eight months to test and calibrate all of the instruments and modes of the James Webb Space Telescope. A scientist on the team explains what it took to get Webb up and running.
Marcia Rieke, Regents Professor of Astronomy, University of Arizona
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/180595
2022-04-11T13:47:27Z
2022-04-11T13:47:27Z
Combined power of two telescopes is helping crack the mystery of eerie rings in the sky
<figure><img src="https://images.theconversation.com/files/457362/original/file-20220411-19-s6ezs4.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some of the MeerKAT's 64 dishes, which astronomers use to collect huge amounts of data.</span> <span class="attribution"><span class="source">© South African Radio Astronomy Observatory (SARAO) </span></span></figcaption></figure><p>When astronomers dream of their ideal telescopes, it’s not that different to what people want from their TVs and computer monitors. Images they produce should be large and high definition, such as those from the Australian Square Kilometre Array Pathfinder (<a href="https://theconversation.com/the-australian-square-kilometre-array-pathfinder-finally-hits-the-big-data-highway-71217">ASKAP</a>), which have ~10k resolution (beyond the typical quality you get from digital TVs and digital cinematography). And they should have a high dynamic range, indicating high quality imaging with deep sensitivity to faint objects.</p>
<p>But not every telescope can do it all. That’s why complementary science – using some telescopes for some tasks, others for different but related tasks, and then combining the data – is so important in astronomy.</p>
<p>The value of complementary science is emphasised in <a href="https://arxiv.org/abs/2203.10669">our recent paper</a>. We worked with ASKAP and South Africa’s <a href="https://theconversation.com/africas-meerkat-first-light-images-have-blown-all-expectations-65246">MeerKAT telescope</a> to harness their different capabilities. In 2019, ASKAP discovered a rare and mysterious type of object, referred to as an “<a href="https://theconversation.com/wtf-newly-discovered-ghostly-circles-in-the-sky-cant-be-explained-by-current-theories-and-astronomers-are-excited-142812">odd radio circle</a>” (ORC). We didn’t know what these eerie glowing rings in the sky were. </p>
<p>It took data from MeerKAT to help us conclude that the circles are most likely enormous shells of gas, about a million light years across, emanating from the central galaxy.</p>
<figure class="align-center ">
<img alt="Graphic of the first odd radio circle discovered (ORC1) in a 2019 image from the Australian SKA Pathfinder (left), and the new detailed image from MeerKAT (right)." src="https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=248&fit=crop&dpr=1 600w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=248&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=248&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=312&fit=crop&dpr=1 754w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=312&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/456885/original/file-20220407-17-shyunu.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=312&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The first odd radio circle discovered (ORC1) in a 2019 image from the Australian SKA Pathfinder (left), and the new detailed image from MeerKAT (right).</span>
<span class="attribution"><span class="source">Author supplied</span></span>
</figcaption>
</figure>
<p>Neither the discovery nor the detail would have been possible without both telescopes. ASKAP’s uniquely large field of view enables the discovery of rare objects like ORCs. It also enabled the discovery of many new Fast Radio Bursts; <a href="https://theconversation.com/how-scientists-are-working-together-to-solve-one-of-the-universes-mysteries-106556">these are</a> seemingly rare, extremely bright and short-lived flashes of radio waves.</p>
<p>Meanwhile, MeerKAT’s unique sensitivity and sampling ability, achieved by its large number of dishes (64, located in a remote part of South Africa’s Northern Cape province), highly sensitive low noise amplifiers and large bandwidth, enables these objects to be studied in greater detail. MeerKAT is the best imaging radio telescope of its kind.</p>
<p>Both ASKAP and MeerKAT are precursors to the <a href="https://www.skatelescope.org/">Square Kilometre Array (SKA)</a>. This is a global project to build the world’s largest and most sensitive radio telescope within the coming decade, co-located in South Africa and Australia. As our new research makes clear, complementary science will be at the heart of the SKA. This is an exciting prospect for African science, with South Africans putting themselves forward as world leaders within radio astronomy. </p>
<h2>The nature of ORC1</h2>
<p>Our new paper focuses on the first ORC that ASKAP discovered in 2019. We call it ORC1. MeerKAT provided something critical to deepening our understanding of what it might be and how it formed: beautiful, detailed images.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=593&fit=crop&dpr=1 600w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=593&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=593&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=746&fit=crop&dpr=1 754w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=746&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/456060/original/file-20220404-13-vx4fdo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=746&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">ORC1 was rendered in more detail by the MeerKAT telescope.</span>
<span class="attribution"><span class="source">Jayanne English using data from MeerKAT and the Dark Energy Survey</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/odd-radio-circles-that-baffled-astronomers-are-likely-explosions-from-distant-galaxies-178290">'Odd radio circles' that baffled astronomers are likely explosions from distant galaxies</a>
</strong>
</em>
</p>
<hr>
<p>The data we collected from MeerKAT was run through a <a href="https://www.ursi.org/proceedings/procGA21/papers/URSIGASS2021-Mo-J11-AM2-3.pdf">complex workflow</a>. This was developed and provided by the <a href="https://www.idia.ac.za">Inter-University Institute for Data Intensive Astronomy (IDIA)</a>, a partnership of three South African universities. This specialised software enabled specific data products to be generated, such as images of ORC1’s polarisation and “radio colour”.</p>
<p>MeerKAT’s technology revealed three especially important and previously uncertain details about ORC1. First was the object’s internal structure, revealed for the first time due to MeerKAT’s deep sensitivity and high resolution. We can now see ORC1 contains multiple arcs, a radio source where the central galaxy is located, and knots of radio emission associated with other galaxies within the vicinity. </p>
<p>Our theory is that the central galaxy, a few billion light years away, caused the ORC during a particular event. This may have been the merging of supermassive black holes or a starburst event (the rapid forming of many stars within the galaxy) that occurred billions of years ago. It was during this event, we hypothesise, that the ORC expanded to its enormous size of about 1.6 million light years. </p>
<p>The second detail revealed by MeerKAT’s data relates to the ORC’s polarisation, made possible by its deep sensitivity.</p>
<p>All light from the electromagnetic spectrum is polarised: its magnetic and electric fields are oriented in a certain direction. However, <a href="https://www.britannica.com/science/wave-particle-duality">waves or photons</a> from an unpolarised source of light are randomly polarised – they do not tend toward any particular orientation. </p>
<p>Certain physical processes, such as the presence of magnetic fields, can polarise light. This causes some or all of the waves to be oriented in the same direction. We found that ORC1 is strongly polarised along its outer ring.</p>
<p>The third detail was the structure of ORC1’s spectral index or “radio colour”: how its brightness changes across frequency. </p>
<p>Typically, spectral index is measured with several radio telescopes combined, each observing at a different frequency that one can compare to see how the brightness changes. For large resolved sources like ORC1, there’s huge scope for uncertainty. MeerKAT’s large bandwidth enabled us to measure an “in-band” spectral index map across the entire source. Within this map, every pixel itself measures the spectral index across the many frequencies we’ve combined. Our resulting map showed a steep spectral index across both the ring and its internal structure, suggesting they may have been produced by the same mechanism.</p>
<p>These new details fit with an explanation where synchrotron radiation (electrons whizzing around magnetic fields) is causing the radio emission, from a shell of gas in the form of a spherical shock wave. However, the internal arcs and rings require further explanation. We hypothesised that these are caused by the nearby galaxies moving through the shell and leaving trails in their wake.</p>
<h2>New questions to pursue</h2>
<p>So, what does it all mean? As with so much radio astronomy, we’re not certain: more data and information added to the mystery, with some clues provided.</p>
<p>However, we have three hypotheses to explain the nature of ORCs. One: it’s a spherical shell from an expanding shock wave caused by a huge explosion, such as the coalescing of two supermassive black holes. Two: it’s a spherical shell from the “termination shock” of a previous “starburst” event – when many stars rapidly formed within the galaxy over a short period of time. Three: it may be a view from one end of powerful radio jets of highly energetic particles that spew out from near a central supermassive black hole.</p>
<p>Not having definite answers may strike some as frustrating. But this is the nature of some science. What’s exciting is that there’s more to come: the SKA, which is due to become operational within the coming decade, will probe even more deeply into faint, rare and mysterious objects. This almost guarantees the discovery of the unexpected, as we’ve seen throughout the history of science, and as we now see with ORCs. Future discoveries far above us may look faint – but the possibilities paint a bright future.</p><img src="https://counter.theconversation.com/content/180595/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jordan Collier works for the Inter-University Institute for Data-Intensive Astronomy. He is affiliated with Western Sydney University and CSIRO Astronomy and Space Science.</span></em></p>
Complementary science will be at the heart of the Square Kilometre Array.
Jordan Collier, ilifu Support Astronomer, Inter-University Institute for Data Intensive Astronomy
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/178290
2022-03-21T19:04:36Z
2022-03-21T19:04:36Z
‘Odd radio circles’ that baffled astronomers are likely explosions from distant galaxies
<figure><img src="https://images.theconversation.com/files/451777/original/file-20220314-22-5opbh8.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C2355%2C2145&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Jayanne English using data from MeerKAT and the Dark Energy Survey</span></span></figcaption></figure><p>In 2019, my colleagues and I discovered spooky glowing rings in the sky using <a href="https://theconversation.com/the-australian-square-kilometre-array-pathfinder-finally-hits-the-big-data-highway-71217">CSIRO’s ASKAP radio telescope</a> in Western Australia. The rings were unlike anything seen before, and we had no idea what they were.</p>
<p>We dubbed them odd radio circles, or ORCs. They continue to puzzle us, but new data from South Africa’s <a href="https://theconversation.com/africas-meerkat-first-light-images-have-blown-all-expectations-65246">MeerKAT</a> telescope are helping us solve the mystery.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/wtf-newly-discovered-ghostly-circles-in-the-sky-cant-be-explained-by-current-theories-and-astronomers-are-excited-142812">'WTF?': newly discovered ghostly circles in the sky can't be explained by current theories, and astronomers are excited</a>
</strong>
</em>
</p>
<hr>
<p>We can now see each ORC is centred on a galaxy too faint to be detected earlier. The circles are most likely enormous explosions of hot gas, about a million light years across, emanating from the central galaxy.</p>
<p><a href="https://arxiv.org/abs/2203.10669">Our paper showing these results</a> has been peer-reviewed and accepted for publication by Monthly Notices of the Royal Astronomical Society. </p>
<h2>A closer look</h2>
<p>We now have beautiful images of one of these rings taken with South Africa’s MeerKAT radio telescope, which shows the ORC in stunning detail. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=542&fit=crop&dpr=1 600w, https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=542&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=542&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=682&fit=crop&dpr=1 754w, https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=682&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/451776/original/file-20220314-19-wyzm9c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=682&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The MeerKAT (green/grey) image of the odd radio circle ORC1 superimposed on an optical image from the Dark Energy Survey.</span>
<span class="attribution"><span class="source">Created by Jayanne English using data from MeerKAT and the Dark Energy Survey.</span></span>
</figcaption>
</figure>
<p>For example, MeerKAT sees a small blob of radio emission in the centre of the ring, which is coincident with a distant galaxy. We are now fairly certain this galaxy generated the ORC. </p>
<p>We see these central galaxies in other ORCs too, all at vast distances from Earth. We now think that these rings surround distant galaxies about a billion light years away, which means the rings are enormous – around a million light years across. </p>
<p>From modelling the faint cloudy radio emission that MeerKAT detects within the rings, it seems the rings are the edges of a spherical shell surrounding the galaxy, like a blast wave from a giant explosion in the galaxy. They look like rings instead of orbs only because the sphere appears brighter at the edges where there is more material along the line of sight, much like a soap
bubble. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5tYr_5sD-RA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Artist’s impression of odd radio circles exploding from a central galaxy. It is thought to take the rings 1 billion years to reach the size we see them today. The rings are so big (millions of light years across), they’ve expanded past other galaxies. <em>Sam Moorfield/CSIRO</em></span></figcaption>
</figure>
<h2>Energetic electrons</h2>
<p>MeerKAT has also mapped the <a href="https://en.wikipedia.org/wiki/Polarization_(waves)">polarisation</a> of the radio waves, which tells us about the magnetic field in the ring. Our polarisation image shows a magnetic field running along the edge of the sphere. </p>
<p>This suggests that an explosion in the central galaxy caused a hot blast to collide with the tenuous gas outside the galaxy. The resulting shock wave then energised electrons in the gas, making them spiral around the magnetic field, generating radio waves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=508&fit=crop&dpr=1 600w, https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=508&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=508&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=638&fit=crop&dpr=1 754w, https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=638&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/449446/original/file-20220302-23-heybxq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=638&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Lines around the edge of the ORC show the direction of the magnetic field. A circular magnetic field like this indicates it has been compressed by a shock wave from the central galaxy.</span>
<span class="attribution"><span class="source">Created by Larry Rudnick from MeerKAT data.</span></span>
</figcaption>
</figure>
<p>One big surprise from the MeerKAT result is that within the ring we see several curved filaments of radio emission. We still don’t know what these are. </p>
<p>But we do know that the sphere is so huge that it has swallowed up other galaxies as it blasted out from the central galaxy. Perhaps the filaments are trails of gas ripped off the galaxies by the passing shock wave?</p>
<h2>Colliding black holes or the birth of millions of stars?</h2>
<p>The big question, of course, is what caused the explosion. We are exploring two possibilities. </p>
<p>One is that they were caused by the merging of two <a href="https://theconversation.com/speaking-with-meg-urry-on-supermassive-black-holes-48375">supermassive black holes</a>. Such a “merger event” releases an enormous amount of energy, enough to generate the ORC. </p>
<p>Another possibility is that the central galaxy went through a “<a href="https://theconversation.com/red-and-dead-future-for-a-galaxy-running-out-of-star-fuel-28912">starburst</a>” event, in which millions of stars were suddenly born from the gas in the galaxy. Such a starburst causes hot gas to blast out from the galaxy, causing a spherical shock wave. </p>
<p>Both black hole mergers and starburst events are rare, which accounts for why ORCs are so rare (only five have so far been reported).</p>
<p>The puzzle of ORCs is not solved yet, and we still have much to learn about these mysterious rings in the sky. So far, we have only detected them with radio telescopes – we see nothing from the rings at optical, infrared, or X-ray wavelengths. </p>
<h2>Getting a better view</h2>
<p>To find out more, we need a tool even more sensitive than MeerKAT and ASKAP. Fortunately, the global astronomical community is building just such an observatory – the <a href="https://www.skatelescope.org/">Square Kilometre Array</a> (SKA), an international effort with telescopes in South Africa and Australia. </p>
<p>ASKAP and MeerKAT were built to test the sites and technology for the SKA. Quite apart from their role as precursors for the SKA, both telescopes have been hugely successful in their own right, making major discoveries in their first years of operation. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/analysis-of-2-000-galaxies-using-the-meerkat-radio-telescope-reveals-fresh-insights-166353">Analysis of 2 000 galaxies using the MeerKat radio telescope reveals fresh insights</a>
</strong>
</em>
</p>
<hr>
<p>Their success in discovering and studying ORCs therefore bodes well for the SKA. </p>
<p>The two telescopes are also beautifully complementary – ASKAP is superb at surveying large areas of sky and finding new objects, while MeerKAT is unrivalled for zooming in on those objects and studying them with higher sensitivity and resolution. </p>
<p>The SKA promises to surpass both. No doubt the SKA will find many more ORCs, and will also be able to probe them to find out what they are telling us about the lifecycle of galaxies.</p><img src="https://counter.theconversation.com/content/178290/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ray Norris is affiliated with CSIRO.</span></em></p>
Next-generation radio telescopes unravel the mysteries of ghostly circles in the sky.
Ray Norris, Professor, School of Science, Western Sydney University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/176602
2022-02-07T13:58:52Z
2022-02-07T13:58:52Z
Astronomers think they’ve just spotted an ‘invisible’ black hole for the first time
<figure><img src="https://images.theconversation.com/files/444789/original/file-20220207-17-1opuin2.jpg?ixlib=rb-1.1.0&rect=0%2C75%2C4476%2C2510&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Concept of a black hole acting as a lens on background light.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/black-hole-gravitational-lens-effect-milky-662787748">Dotted Yeti/Shutterstock</a></span></figcaption></figure><p>Astronomers famously <a href="https://theconversation.com/first-black-hole-photo-confirms-einsteins-theory-of-relativity-115167">snapped the first</a> ever direct image of a black hole in 2019, thanks to material glowing in its presence. But many black holes are actually near impossible to detect. Now another team using the <a href="https://theconversation.com/hubbles-deep-field-images-of-the-early-universe-are-postcards-from-billions-of-years-ago-40519">Hubble Space Telescope</a> seems to have finally found something nobody has seen before: a black hole which is completely invisible. The research, which has been <a href="https://arxiv.org/abs/2201.13296">posted online</a> and submitted for publication in the Astrophysical Journal, is yet to be peer-reviewed.</p>
<p>Black holes are what’s left after large stars die and their cores collapse. They are incredibly dense, with gravity so strong that nothing can move fast enough to escape them, including light. Astronomers are <a href="https://theconversation.com/a-brief-history-of-black-holes-107298">keen to study</a> black holes because they can tell us a lot about the ways that stars die. By measuring the masses of black holes, we can learn about what was going on in stars’ final moments, when their cores were collapsing and their outer layers were being expelled.</p>
<p>It may seem that black holes are by definition invisible – they after all earned their name through their ability to trap light. But we can still detect them through the way they interact with other objects thanks to their strong gravity. Hundreds of small black holes have been detected by the way they interact with other stars. </p>
<p>There are two different approaches to such detection. In “<a href="https://www.cosmos.esa.int/web/cesar/x-ray-binaries-monitoring">X-ray binary stars</a>” – in which a star and a black hole orbit a shared centre while producing X-rays – a black hole’s gravitational field can pull material from its companion. The material circles the black hole, heating up by friction as it does so. The <a href="https://theconversation.com/first-black-hole-photo-confirms-einsteins-theory-of-relativity-115167">hot material glows</a> brightly in X-ray light, making the black hole visible, before being sucked into the black hole and disappearing. You can also detect pairs of black holes as they merge together, spiralling inwards and emitting a brief flash of <a href="https://theconversation.com/gravitational-waves-found-the-inside-story-54589">gravitational waves</a>, which are ripples in spacetime.</p>
<figure class="align-center ">
<img alt="Image of a black hole." src="https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=350&fit=crop&dpr=1 600w, https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=350&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=350&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=439&fit=crop&dpr=1 754w, https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=439&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/440259/original/file-20220111-16-71qdkv.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=439&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">First image of a black hole.</span>
<span class="attribution"><span class="source">Event Horizon Telescope collaboration et al.</span></span>
</figcaption>
</figure>
<p>There are many rogue black holes that are drifting through space without interacting with anything, however – making them hard to detect. That’s a problem, because if we can’t detect isolated black holes, then we can’t learn about <a href="https://theconversation.com/black-holes-we-think-weve-spotted-the-mysterious-birth-of-one-174726">how they formed</a> and about the deaths of the stars they came from. </p>
<h2>New, dark horizons</h2>
<p>To discover such an invisible black hole, the team of scientists had to combine two different types of observations over several years. This impressive achievement promises a new way of finding the previously elusive class of isolated black holes.</p>
<p>Einstein’s <a href="https://theconversation.com/will-we-have-to-rewrite-einsteins-theory-of-general-relativity-50057">General Theory of Relativity</a> predicted that massive objects will bend light as it travels past them. That means that any light passing very close to an invisible black hole – but not close enough to end up inside it – will be bent in a similar way to light passing through a lens. This is called <a href="https://theconversation.com/how-we-managed-what-einstein-thought-was-impossible-and-used-his-theory-to-weigh-a-star-79050">gravitational lensing</a>, and can be spotted when a foreground object aligns with a background object, bending its light. The method has already been used to study everything from clusters of galaxies to planets around other stars. </p>
<p>The authors of this new research combined two types of gravitational lensing observations in their search for black holes. It started with them spotting light from a distant star suddenly magnify, briefly making it appear brighter before going back to normal. They could not see any foreground object that was causing the magnification via the process of gravitational lensing, though. That suggested the object might be a lone black hole, something which had never been seen before. The problem was that it could also just have been a faint star.</p>
<p>Figuring out if it was a black hole or a faint star required a lot of work, and that’s where the second type of gravitational lensing observations came in. The authors repeatedly took images with Hubble for six years, measuring how far the star appeared to move as its light was deflected. </p>
<p>Eventually this let them calculate the mass and distance of the object which caused the lensing effect. They found it was about seven times the mass of our Sun, located about 5,000 light years away, which sounds far away but is actually relatively close. A star that size and that close should be visible to us. Since we can’t see it, they concluded it must be an isolated black hole.</p>
<p>Taking that many observations with an observatory like Hubble isn’t easy. The telescope is very popular and there is a lot of competition for its time. And given the difficulty of confirming an object like this, you might think the prospects for finding more of them aren’t great. Luckily, we’re at the beginning of a revolution in astronomy. This is thanks to a new generation of facilities, including the ongoing <a href="https://sci.esa.int/web/gaia">Gaia survey</a>, and upcoming <a href="https://www.lsst.org/science">Vera Rubin Observatory</a> and <a href="https://roman.gsfc.nasa.gov/">Nancy Grace Roman Space Telescope</a>, all of which will take repeated measurements of large parts of the sky in unprecedented detail.</p>
<p>That’s going to be huge for all areas of astronomy. Having regular, high-precision measurements of so much of the sky will let us investigate en masse things which change on very short timescales. We’ll study things as varied as asteroids, exploding stars known as supernovas, and planets around other stars in new ways.</p>
<p>When it comes to the search for invisible black holes, that means rather than celebrating finding just one, we could soon be finding so many that it becomes routine. That will let us fill in the gaps in our understanding of the deaths of stars and the creation of black holes. </p>
<p>Ultimately, the galaxy’s invisible black holes are about to find it much harder to hide.</p><img src="https://counter.theconversation.com/content/176602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Adam McMaster receives funding from the Science and Technology Facilities Council, DISCnet, and the Open University Space SRA.</span></em></p><p class="fine-print"><em><span>Andrew Norton has previously received funding from the UK Science & Technology Facilities Council. </span></em></p>
Some black holes are isolated in space and therefore near impossible to detect.
Adam McMaster, Postgraduate Research Student (PhD) in Astronomy, The Open University
Andrew Norton, Professor of Astrophysics Education, The Open University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/172284
2022-01-06T13:12:25Z
2022-01-06T13:12:25Z
Real shooting stars exist, but they aren’t the streaks you see in a clear night sky
<figure><img src="https://images.theconversation.com/files/438524/original/file-20211220-13-qw05dm.jpeg?ixlib=rb-1.1.0&rect=1279%2C294%2C970%2C829&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Some stars travel at high speeds through the universe and sometimes leave spectacular clouds of dust and gas in their wake. </span> <span class="attribution"><a class="source" href="https://esahubble.org/images/opo0903a/">NASA, ESA and R. Sahai (NASA's Jet Propulsion Laboratory)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>“I see thy glory like a shooting star.”</p>
<p>So says the Earl of Salisbury as he ruminates about the future in Shakespeare’s “Richard II.” </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white print of many streaks of light in the sky above a small town." src="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=919&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=919&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=919&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1154&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1154&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438527/original/file-20211220-13-pb34p1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1154&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shooting stars – such as those produced by the Leonid meteor shower depicted in this print from 1889 – are beautiful, but they have nothing to do with real stars.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Leonids#/media/File:Leonids-1833.jpg">Adolf Vollmy/WikimediaCommons</a></span>
</figcaption>
</figure>
<p>During the English Renaissance, people believed shooting stars were luminaries falling from the heavens and <a href="https://doi.org/10.2307/776821">harbingers of calamity</a>. But by the end of the 19th century, <a href="https://doi.org/10.1016/0083-6656(82)90010-1">scientists had established</a> the truth to be far more mundane. What today are commonly called <a href="https://theconversation.com/curious-kids-what-makes-a-shooting-star-fall-111068">shooting or falling stars</a> are simply small pieces of rock or dust that quickly burn up upon entering Earth’s atmosphere. </p>
<p>But nature has a surprise for you – shooting stars really do exist.</p>
<p><a href="https://sites.google.com/a/cfa.harvard.edu/idanginsburg/home">I am an astrophysicist</a> who studies <a href="http://www.scholarpedia.org/article/Celestial_mechanics">celestial mechanics</a> – how objects like stars, planets and galaxies move. </p>
<p>From 2005 to 2014, a monumental <a href="https://doi.org/10.1088/0004-637X/787/1/89">observing program</a> incorporating the <a href="https://www.sdss.org/">Sloan Digital Sky Survey</a> and telescopes at the <a href="https://www.cfa.harvard.edu/facilities-technology/cfa-facilities/fred-lawrence-whipple-observatory-mt-hopkins-az">Fred Lawrence Whipple Observatory</a> confirmed a new class of stars that move with such incredible speed that they can escape the gravity of their home galaxies. </p>
<p>Astronomers are just beginning to understand these real-life shooting stars – called <a href="https://doi.org/10.1146/annurev-astro-082214-122230">hypervelocity stars</a> – that zoom through the cosmos at millions of miles per hour. </p>
<h2>Spinning stars and slingshots</h2>
<p>The story of hypervelocity stars begins in 1988, when Jack Gilbert Hills, a theoretician at <a href="https://www.lanl.gov/">Los Alamos National Labs</a>, had an inspired idea: What would happen if a binary star system – that is, two stars that are gravitationally bound to each other and orbit a common center of mass – traveled near the massive black hole at the center of the Milky Way? <a href="https://doi.org/10.1038/331687a0">Hills calculated</a> that the <a href="https://spacemath.gsfc.nasa.gov/blackh/4Page33.pdf">tidal force</a> of the black hole could rend the binary system in two. </p>
<p>Imagine two ice skaters holding hands and spinning around until they all of a sudden let go. The two skaters will fly away from each other. Similarly, when two stars in a binary system are wrenched apart by a close encounter with a black hole, they will fly apart. In such an encounter one star might gain enough energy to be slingshotted out of the galaxy entirely. </p>
<p>Astronomers now know that this is how hypervelocity stars are born. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A bluish white star leaving the Milky Way galaxy." src="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438529/original/file-20211220-13-1fiwrso.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A hypervelocity star, HE 0437-5439, was thrown from the center of the Milky Way and is on a one-way trip out of the galaxy.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/hubble/science/expelled-star.html">NASA, ESA and G. Bacon (STScI)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Theory, observations and simulations</h2>
<p>After the publication of Hills’ prescient paper, the astronomy community considered hypervelocity stars an intriguing possibility, albeit one without observational evidence. That changed in 2005. </p>
<p>While observing stars in the <a href="https://theconversation.com/dark-matter-and-the-milky-way-more-little-than-large-32792">Milky Way’s halo</a>, a team of researchers using the <a href="https://www.mmto.org/">MMT Observatory</a> in Arizona came across something most unexpected. They observed a star escaping the Milky Way at nearly 2 million mph (3.2 million kph). This was <a href="https://doi.org/10.1086/429378">HVS1</a>, the first known hypervelocity star. </p>
<p>Observations tell part of the story, but to help answer other questions – such as what happens to the companion after it separates from the hypervelocity star – my adviser and I turned to computer simulations. Our models predict that the other star in the former pair is often <a href="https://doi.org/10.1111/j.1365-2966.2006.10091.x">left orbiting the black hole</a> in much the same fashion as the Earth orbits the Sun.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Many blue circular lines against the backdrop of space." src="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438530/original/file-20211220-15-14excla.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simulations use the laws of physics to calculate the orbits and trajectories of stars, including hypervelocity stars.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1825d/">ESO/L. Calçada/spaceengine.org</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Another exciting result from these modeling efforts was the discovery that sometimes the <a href="https://doi.org/10.1111/j.1365-2966.2007.11461.x">two stars can crash into each other</a>. When this happens, the stars may coalesce into one very massive star.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A dark planet against the backdrop of the Milky Way." src="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=785&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=785&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=785&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=986&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=986&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438531/original/file-20211220-23-ylozwp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=986&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Planets might also be flung out of the galaxy at stupefying speeds.</span>
<span class="attribution"><a class="source" href="https://insider.si.edu/2012/03/planet-starship-runaway-planets-zoom-at-a-fraction-of-light-speed/">David A. Aguilar/CfA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>If you were wondering what might befall a planet orbiting one of these stars, we modeled that too. In a <a href="https://doi.org/10.1111/j.1365-2966.2012.20930.x">short paper from 2012</a>, my colleagues and I showed that the black hole in the center of our galaxy can blast planets out of the Milky Way at nearly 5% the speed of light.</p>
<p>As of today, no hypervelocity planets have been detected, but <a href="https://doi.org/10.1093/mnras/stw3213">they very well might be out there</a>, waiting for some happy astronomers to chance upon them.</p>
<h2>Not all fast stars leave the galaxy</h2>
<p>Utilizing data from the <a href="https://sci.esa.int/web/gaia">Gaia spacecraft</a>, launched in 2013, my colleagues and I discovered that some of the stars that the astronomy community had previously considered “hypervelocity stars” are in fact <a href="https://doi.org/10.1093/mnras/sty1601">likely bound to the Milky Way galaxy</a>. </p>
<p>While this result may sound disappointing, it actually reveals two critical points. First, there are different mechanisms to accelerate stars to high speeds. Today astronomers know of <a href="https://doi.org/10.1063/PT.3.3199">thousands of speedy stars</a>. However, just because a star is moving fast does not necessarily make it a hypervelocity star unbound from the Milky Way. Second, true hypervelocity stars that are escaping the Milky Way may be rarer than previously thought. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A circular spacecraft in space." src="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=398&fit=crop&dpr=1 600w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=398&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=398&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=500&fit=crop&dpr=1 754w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=500&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/438532/original/file-20211220-15-t4nakp.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=500&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Data from both ground- and space-based telescopes like Gaia help astronomers learn more about all types of high-velocity stars, including hypervelocity stars.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/missions/gaia/in-depth/">ESA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>The future is bright and fast</h2>
<p>I find it beautiful that true shooting stars exist. It’s equally amazing that studying their trajectories and velocities can help answer some of the foremost questions in science today. </p>
<p>For instance, hypervelocity stars could offer clues to the <a href="https://doi.org/10.1086/496958">nature and distribution of dark matter</a> in the universe. Hypervelocity stars may also be the key to answering whether there is <a href="https://theconversation.com/supermassive-black-hole-at-the-center-of-our-galaxy-may-have-a-friend-128295">more than one black hole</a> at the center of the galaxy. </p>
<p>My students are using NASA’s <a href="https://tess.mit.edu/">Transiting Exoplanet Survey Satellite</a> to search for planets around these blisteringly fast stars. The discovery of even one planet around a hypervelocity star will forever change ideas of planetary formation and survivability. </p>
<p>These stars are speedy, but slowly they are shedding light on nature’s secrets. While you may not be able to see a real shooting star with your own eyes, you certainly can make a wish upon one.</p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-favorite">Weekly on Wednesdays</a>.]</p><img src="https://counter.theconversation.com/content/172284/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Much of the research on hypervelocity stars conducted by Idan Ginsburg and discussed in this article was made possible from various grants and institutions, all of which are properly acknowledged in the relevant published journal articles and available online. </span></em></p>
Hypervelocity stars were discovered only 15 years ago and are the closest things in existence to real shooting stars. They travel at millions of miles per hour, so fast that they can escape from galaxies.
Idan Ginsburg, Academic Faculty in Physics & Astronomy, Georgia State University
Licensed as Creative Commons – attribution, no derivatives.
tag:theconversation.com,2011:article/172233
2021-12-26T20:24:30Z
2021-12-26T20:24:30Z
Hunting galaxies far far away – here’s how anyone can explore the universe
<figure><img src="https://images.theconversation.com/files/434739/original/file-20211130-16-17byu9f.png?ixlib=rb-1.1.0&rect=58%2C2%2C1296%2C723&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p><em>This article is part of a <a href="https://theconversation.com/au/topics/how-to-guides-113946">series</a> explaining how readers can learn the skills to take part in activities that academics love doing as part of their work.</em></p>
<hr>
<p>By far my favourite thing about my job as an astronomer is those rare moments when I get to see beautiful distant galaxies, whose light left them millions to billions of years ago. It’s a combination of pure awe and scientific curiosity that excites me about “galaxy hunting”.</p>
<p>In astronomy today, much of our work is handling enormous amounts of data by writing and running programs to work with images of the sky. A downside to this is that we don’t always have that “hands-on” experience of looking at every square inch of the universe while we study it. I’m going to show you, though, how I get my fix of wonder by looking at galaxies that only a select few people will ever have seen, until now. </p>
<p>In just our <a href="https://science.nasa.gov/observable-universe">observable universe</a> we estimate there are over 2 trillion galaxies! </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/curious-kids-how-are-galaxies-formed-171907">Curious Kids: how are galaxies formed?</a>
</strong>
</em>
</p>
<hr>
<h2>Galaxies at your fingertips</h2>
<p>Only a few decades ago astronomers had to tediously examine photographic plates after a long, cold and lonely night of observing. In the 21st century we have access to information any time, anywhere via the internet. </p>
<p>Automatic telescopes and surveys now provide us with so much data we require machines to help us analyse it. In some cases human eyes will only ever look at what the computers have deemed is interesting! Massive amounts of data are hosted online, just waiting to be admired, for free. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/new-powerful-telescopes-allow-direct-imaging-of-nascent-galaxies-12-billion-light-years-away-74910">New powerful telescopes allow direct imaging of nascent galaxies 12 billion light years away</a>
</strong>
</em>
</p>
<hr>
<h2>Go online for a universe atlas</h2>
<p><a href="https://aladin.u-strasbg.fr/AladinLite/">Aladin Lite</a> is one of the greatest online tools available to look at our universe through the eyes of many different telescopes. Here we can scan the entire sky for hidden galaxies, and even decipher information about their stellar populations and evolution. </p>
<p>Let’s start our universal tour by searching for one of the most visually stunning galaxies out there, the Cartwheel Galaxy. In the Aladin interface, you can search for both the popular name of an object (like “cartwheel galaxy”) or known co-ordinates. The location will be centred in the interface. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=328&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=328&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=328&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=412&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=412&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434683/original/file-20211130-13-16pqn2r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=412&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Online view in Aladin Lite of the Cartwheel Galaxy, a lenticular/ring galaxy 500 million light years away from Earth discovered in 1941 by iconic astronomer Fritz Zwicky.</span>
</figcaption>
</figure>
<p>The first image of the Cartwheel Galaxy we see is from optical imaging by the Digitised Sky Survey. The colours we see represent different filters from this telescope. However, these are fairly representative of what the galaxy would look like with our own eyes. </p>
<p>A general rule of thumb as an astronomer is that “colour” differences within galaxies are because of physically different environments. It’s important to note that things that look blue (shorter wavelengths) are generally hotter than things that look red (longer wavelengths). </p>
<p>In this galaxy, the outer ring appears to be more blue then the centre red section. This might hint at star formation and stellar activity happening in the outer ring, but less so in the centre.</p>
<p>To confirm our suspicions of star formation we can select to look at data from different surveys, in different wavelengths. When young stars are forming, vast amounts of UV radiation are emitted. By changing the survey to GALEXGR6/AIS, we are now looking at only UV wavelengths, and what a difference that makes! </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434735/original/file-20211130-17-h8oqro.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Online view in Aladin Lite of the Cartwheel Galaxy in GALEX UV wavelengths.</span>
</figcaption>
</figure>
<p>The whole centre section of the galaxy seems to “disappear” from our image. This suggests that section is likely home to older stars, with less active <a href="https://link.springer.com/chapter/10.1007%2F978-1-4612-2232-3_15">stellar nurseries</a>. </p>
<p>Aladin is home to 20 different surveys. They provide imaging of the sky from optical, UV, infrared, X and gamma rays. </p>
<p>When I am wandering the universe looking for interesting galaxies here, I generally start out in optical and find ones that look interesting to me. I then use the different surveys to see how the images change when looking at specific wavelengths. </p>
<h2>Universal Where’s Wally</h2>
<p>Now you’ve had a crash course in galaxy hunting, let the game begin! You can spend hours exploring the incredible images and finding interesting-looking galaxies. I recommend looking at images from DECalS/DR3 for the highest resolution and detail when zooming further in. </p>
<p>The best method is to just drag the sky atlas around. If you find something interesting, you can find out any information we have on it by selecting the target icon and clicking on the object.</p>
<p>To help you on your galactic expedition here are my favourite finds of the different types of objects you might see. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434733/original/file-20211130-20-7ub9nq.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Examples of spiral galaxies found using Aladin online. Spirals are the most iconic galaxy shape and include many of the brightest galaxies in the nearby universe, like the Andromeda Galaxy.</span>
</figcaption>
</figure>
<p><strong><a href="https://astronomy.swin.edu.au/cosmos/S/spiral+galaxy">Spiral galaxies</a></strong> typically have a central rotating disc with large spiral “arms” curving out from the denser central regions. They are incredibly beautiful. Our own Milky Way is a spiral galaxy. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-our-milky-way-galaxy-a-zombie-already-dead-and-we-dont-know-it-52732">Is our Milky Way galaxy a zombie, already dead and we don't know it?</a>
</strong>
</em>
</p>
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<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=286&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=286&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=286&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=359&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=359&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434737/original/file-20211130-15-1sgwvgj.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=359&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Examples of elliptical galaxies. This type of galaxy has an approximately ellipsoidal shape and a smooth, nearly featureless image.</span>
</figcaption>
</figure>
<p><strong><a href="https://astronomy.swin.edu.au/cosmos/E/Elliptical+Galaxy">Elliptical galaxies</a></strong> are largely featureless and less “flat” then spirals, with stars occupying almost a 3D ellipse at times. These type of galaxies tend to have older stars and less active star-forming regions compared to spiral galaxies.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=273&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=273&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=273&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=342&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=342&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434741/original/file-20211130-13-339x0w.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=342&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Examples of lenticular galaxies. These are a type of galaxy intermediate between elliptical and a spiral galaxies.</span>
</figcaption>
</figure>
<p><strong><a href="https://astronomy.swin.edu.au/cosmos/L/Lenticular+Galaxy">Lenticular galaxies</a></strong> appear like cosmic pancakes, fairly flat and featureless in the night sky. These galaxies can be thought of as the “in between” of spiral and elliptical galaxies. The majority of star formation has stopped but lenticular galaxies can still have significant amounts of dust in them. </p>
<p>There are also other amazing types of galaxies, including <a href="https://pweb.cfa.harvard.edu/research/topic/galaxies-merging-and-interacting">mergers</a> and <a href="https://public.nrao.edu/gallery/what-is-a-lensed-galaxy/">lenses</a>, which are just waiting for you to find them. I’d love to see what amazing things you find over on Twitter at @sarawebbscience. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-ways-families-can-enjoy-astronomy-during-the-pandemic-144647">5 ways families can enjoy astronomy during the pandemic</a>
</strong>
</em>
</p>
<hr>
<p><em>You can read other articles in this series <a href="https://theconversation.com/au/topics/how-to-guides-113946">here</a>.</em></p><img src="https://counter.theconversation.com/content/172233/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sara Webb does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>
Anyone with an internet connection can search the universe and possibly discover never-before-seen galaxies.
Sara Webb, Postdoctoral Research Fellow, Centre for Astrophysics and Supercomputing, Swinburne University of Technology
Licensed as Creative Commons – attribution, no derivatives.