Space And The Universe News

  • Astronomer Working With Webb Said the new Images “Almost Brought him to Tears.” We’ll see Them on July 12th
    by Matt Williams on July 3, 2022 at 7:17 pm

    The scientific and astronomical community are eagerly waiting for Tuesday, July 12th, to come around. On this day, the first images taken by NASA’s James Webb Space Telescope (JWST) will be released! According to a previous statement by the agency, these images will include the deepest views of the Universe ever taken and spectra obtained from an exoplanet atmosphere. In another statement issued yesterday, the images were so beautiful that they almost brought Thomas Zarbuchen – Associate Administrator for NASA’s Science Mission Directorate (SMD) – to tears!

    The James Webb Space Telescope is the most powerful and complex observatory ever deployed, not to mention the most expensive ($10 billion)! Because of its complex system of mirrors and its advanced sun shield, the telescope had to be designed so that it could be folded up (origami style) to fit inside a payload fairing, then unfold once it reached space. To ensure everything would work, the telescope had to be rigorously tested, a process that caused several delays and cost overruns (a situation made worse by the COVID pandemic).

    Engineering images of sharply focused stars in the field of view of each instrument demonstrate that the telescope is fully aligned and in focus. Credit: Credit: NASA/ESA/STScI

    Since it launched on Christmas Day in 2021, the observatory has successfully unfolded, commissioned its science instruments, and reached the L2 Lagrange Point, where it will remain for its entire mission. It also successfully aligned all 18 of its segmented mirrors, which are arranged in a honeycomb configuration that measures 6.5 meters (more than 21 feet) in diameter – almost three times the size of Hubble’s primary mirror. Previously, NASA released test images the JWST took of a star 2,000 light-years from Earth in the direction of the constellation Ursa Major (HD 84406).

    According to Zurbuchen, who saw the images during a Wednesday briefing with other NASA officials, the first-light images it has taken provide a “new worldview” into the cosmos. Addressing what it was like to see the first-light images at the Wednesday news conference, Zarbuchen said:

    “The images are being taken right now. There is already some amazing science in the can, and some others are yet to be taken as we go forward. We are in the middle of getting the history-making data down. It’s really hard to not look at the Universe in a new light and not just have a moment that is deeply personal. It’s an emotional moment when you see nature suddenly releasing some of its secrets, and I would like you to imagine and look forward to that.”

    During the news conference, NASA officials said that the images and other data would include the deepest-field image of the Universe ever taken. The previous record-holder was the image acquired as part of the Hubble Ultra Deep Field, which included 10,000 galaxies of various ages, colors, and distances in the direction of the constellation Fornax. The 100 oldest galaxies in the image (shown below) appear deep red and were dated to just 800 million years after the Big Bang, making them the most distant and oldest ever viewed.

    This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. Credit: NASA/ESA

    The James Webb images peer even further into the cosmos and reveal what galaxies looked like just a few hundred million years after the Big Bang. These earliest galaxies were instrumental in dispelling the “Cosmic Dark Ages,” a period where the Universe was permeated by neutral hydrogen atoms and therefore invisible to modern instruments. Astronomers know what the Universe looked like just prior to this period, thanks to the relic radiation from the Big Bang, which is visible to our instruments – the Cosmic Microwave Background (CMB).

    As a result, astronomers have been unable to see what the earliest galaxies looked like since their formation coincides with the Dark Ages. But thanks to its advanced infrared imaging capabilities, James Webb can pierce the veil of “darkness” and see what galaxies initially looked like. This will allow scientists to model and simulate the evolution of cosmic structures with far greater accuracy, which could also provide fresh insight into the role of Dark Matter and Dark Energy in cosmic evolution.

    Another image will provide the public with something else they’ve never seen before (which James Webb is ideally suited to provide). This image will feature an exoplanet, as well as spectral data from its atmosphere obtained by its advanced suite of spectrographs. These instruments allow astronomers to observe chemical signatures from an exoplanet by observing how light is absorbed (and at which wavelengths) in its atmosphere. These signatures will reveal the atmosphere’s composition, which could include oxygen gas, nitrogen, and carbon dioxide, the very things we associate with “habitability.”

    Even more exciting, these same observations could reveal traces of methane gas, ammonia, and other chemicals indicative of biological processes that we associate with life (aka. “biosignatures”). Last, but not least, the presence of chemicals like chlorofluorocarbons and others we associate with industrial processes would be seen as indications of advanced life (aka. “technosignatures”). In short, images by James Webb will allow astronomers to model the evolution of the cosmos, place tighter constraints on which exoplanets are “habitable,” and could even reveal that humanity is not alone in the Universe.

    There are many other things that James Webb will study during its primary science operations (which will last until 2028) and its ten-year mission (which is expected to be extended to 20 years). This will include the dust and gas that make up the interstellar medium (ISM), debris disks around young stars, planetary systems in the process of formation, cooler objects like M-type (red dwarf) stars and brown dwarfs, and the center of the Milky Way Galaxy.

    And it all starts with these “first-light” images, which NASA says it plans to release on July 12th, starting at 10:30 AM EDT (08:30 AM PDT). According to NASA’s deputy administrator, Pam Melroy, these first images were emotionally overwhelming for her too. “What I have seen moved me, as a scientist, as an engineer, and as a human being,” she said. While the rest of us will have to wait another eight days, the teasers we’ve been treated to suggest that the years of delays, retesting, and cost overruns will totally be worth it!

    You can check out the images by going to NASA’s JWST mission page. As of the publication of this article, there are just 8 days, 19 hours, and 12 minutes to go!

    Further Reading: ArsTechnica

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  • The United States announces a stop to testing Anti-Satellite Weapons
    by Cathrine Versfeld on July 2, 2022 at 8:08 pm

    The United States Government has declared that it will no longer be performing tests of Anti-Satellite (ASAT) weapons. In a public statement during a visit to the Vandenberg Space Force Base, Vice President Kamala Harris confirmed that this policy has the primary purpose of setting an example to other countries. It represents an important step in the direction of establishing “space norms” for all countries to follow.

    ASAT weapons go as far back as the early years of the Cold War. According to the Naval Institute Guide to World Naval Weapons Systems, ASAT weapons were designed for strategic and tactical military purposes. Satellites have long been used by the military for navigation, communication, and gathering intel on enemy movements and activities through sophisticated satellite imaging: Spy satellites.

    Although ASAT weapons have never been used in actual warfare, China, India, Russia, and the USA have all demonstrated their capability. These weapons have so far only been used by these countries in tests against their own targets, such as decommissioned satellites.

    If you’re wondering why it would even be necessary to blast your own satellites out of the sky, it may help to remember that this reminds anybody who’s watching that they can destroy a satellite at will. It’s a threat: “If you threaten our infrastructure, we can retaliate.” But each successful test hurls thousands of new pieces of debris into orbit.

    Conceptual rendering of pollution in orbit around earth

    The risks of space junk might not seem obvious at first. After all, space is enormous, and you might not think it’s very likely that a few bits and pieces might hit something important. But it’s worth remembering that every single object in space, from the International Space Station (ISS) down to the smallest fleck of paint, is hurtling around the Earth at enormous speed, and we keep putting more things up there.
    The United Nations Office for Outer Space Affairs (UNOOSA) keeps an index of objects launched into space. At the end of January 2022, this list counted 8261 individual satellites, an increase of almost 12% over the previous 10 months. And as Starlink and its rivals settle down to the business of building their mega-constellations of communications satellites, this growth is only going to accelerate. In fact, there have already been collisions between satellites, and it is no longer unusual for satellite owners to dodge each other’s satellites.

    Photograph of Canadaarm2 hit by a piece of space debris

    So as harmless as it may seem to explode your own things in space, there is a very real threat looming. Every time a satellite is destroyed, whether it was attacked by ASAT weaponry or simply collided with something, that results in thousands of tiny bits of debris spreading out across the original satellite’s orbit. On earth, this would just mean a lot of litter to pick up, but in space, and in orbit, this means thousands of shards of metal, plastic, and ceramics orbiting the planet many times faster than a rifle bullet.

    A good example of this was when Russia performed its most recent ASAT test in November 2021. Debris from the destroyed satellite came dangerously close to the International Space station, and emergency action was needed to move it out of harm’s way. This is at the heart of the problem. Most of the larger debris from tests like this can be tracked with ground-based radar, which is how satellite operators can be warned in advance, but the smaller stuff is effectively invisible. Depending on how high up it is, it could stay in orbit for a very long time.

    Addressing this problem has been the main purpose of VP Harris’s announcement. By setting norms like this, it is hoped that other countries will follow suit. According to Robin Dicky, chief analyst at the Aerospace Center for Space Policy and Strategy, “There are tons of different norms conversations happening — there’s no one size fits all solution for how to develop them. The approach that you take is likely to be very different depending on the content and context.”


    The global astronomy community and scientists worldwide fully support the idea of eliminating space debris, which includes the use of anti-satellite testing, but it may still take time for this to become a reality. Russia and China have disconnected themselves from European and US Space programs, which makes the prospect of a “universal protocol” difficult to achieve at this stage.

    It may take longer than we hope, but circumstances aren’t as bleak as they may seem. Projects like ClearSpace1 are underway to manage “space junk” by collecting it and performing controlled atmospheric burns. And if we can reach a global agreement to end ASAT, it sets the groundwork for sustainable long-term management. This historic announcement by VP Harris is an important step in the right direction.

    At the rate that we’re putting things into orbit, reaching a consensus between all private enterprises and space agencies will become vital. According to the MIT Technology Review, by 2025 there could be as many as 1,100 satellites launching each year. As Dicky puts it, “Setting these common expectations for what’s acceptable and not acceptable in space is a crucial step to make sure that space is safe and usable for all in the decades to come.”

    The increasing volume of things orbiting earth will become a problem in the near future.

    More information: Carnegie Institution

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  • Mystery Rocket Crash Site, ISS Independence, Space Nuclear Power
    by Anton Pozdnyakov on July 2, 2022 at 12:33 am

    NASA teases JWST images, Rocket Lab launches CAPSTONE, mystery rocket’s crash site found on the Moon, how magnetars are created, ISS gets more independent from Russia and more.

    If you prefer the news being videoed at you instead of reading them, we’ve got you covered! Here’s a video version of this week’s most important space and astronomy news.

    Mystery Rocket Crash Site Found, ISS Independence from Russia, Space Nuclear Power

    Astronomer Working With Webb Said the new Images “Almost Brought him to Tears”. We’ll see Them on July 12th

    NASA continues to tease us with upcoming images from JWST. This week they held a conference where they unveiled some details about what we should expect. The telescope is in very good shape, it’s diffraction limit is almost twice better than expected. As for the first images, there was a hint that we should see ‘the deepest image of the Universe yet’ as well as data on an exoplanet. All that is coming on July 12th.

    For more information on James Webb, check out this week’s episode of Weekly Space Hangout with Lee Feinberg, who is NASA Optical Telescope Element (OTE) Manager for the James Webb Space Telescope at NASA’s Goddard Space Flight Center in Greenbelt. A great interview with lots of amazing insights on JWST.

    NASA Funds the Development of a Nuclear Reactor on the Moon That Would Last for 10 Years

    NASA’s concept of a nuclear reactor for the Moon

    When the Artemis program brings humans back to the Moon, they will eventually stay, building up a research station on the lunar surface. They will need a lot of power to heat and cool the station, run their experiments and communications, and generate oxygen from local materials. They can’t rely on solar energy since the Moon is in shadow for two weeks every month. NASA has paid three companies to develop plans for 40 kW fission reactors that could work on the surface of the Moon for ten years.

    More on NASA’s nuclear power development.

    Rocket Lab’s Electron rocket launches NASA’s CAPSTONE

    Capstone launch

    A new NASA CubeSat was launched this week on top of a Rocket Lab Electron rocket. The mission is called the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, or CAPSTONE. Its purpose is to travel the same orbit near the Moon that the upcoming Lunar Gateway will take. This will help NASA understand if the orbit is stable and as helpful as they’re hoping, allowing astronauts to reach the surface of the Moon safely with less energy.

    More about NASA’s CAPSTONE launch.

    Mystery Rocket’s Crash Site Found on the Moon

    Earlier this year, we reported that a booster rocket was on a collision course with the Moon and was about to carve out a new crater. The booster was initially identified as a SpaceX booster from NASA’s DSCOVR mission and then as the booster from China’s Chang’e-5 mission. The object crashed into the Moon, as predicted, and a new image reveals a rare double crater. It’s believed that the spacecraft broke up through tidal forces with the Moon, creating the double impact.

    More about Moon’s crash site.

    Independence from Russia’s Progress is coming for the ISS

    A Northrop Grumman Cygnus cargo spacecraft recently detached from the International Space Station, carrying garbage away. Before it left, though, it was able to boost the orbit of the ISS. Usually, this maneuver is done by the Russian Zvezda module or spacecraft attached to the station. This demonstrated that the US could keep the station aloft as well, so it’s not reliant on Russia anymore, who has even threatened to let the station crash uncontrollably into the Earth.

    More about Cygnus’ first boost of the ISS.

    Giant Sunspot AR3038 has Doubled in Size and is Pointed Right at Earth. Could be Auroras Coming

    The Sun’s activity is steadily increasing as it moves towards the time of solar maximum. This means sunspots, coronal mass ejections, solar flares… and auroras here on Earth. A giant sunspot region suddenly doubled in size and was oriented directly towards the Earth. If it had released a flare, we could have seen increased aurora activity on Earth. It didn’t and has now rotated away from us, but other sunspots will be facing us soon, so get ready to see the Northern Lights (or Southern Lights).

    More about Sun’s activity this week.

    The Most Threatening Asteroid Just got Downgraded to “Harmless”. No Impact in 2052

    ESA released some good news on asteroid 2021 QM1. Originally it was considered one of the more dangerous asteroids out there with a risk of a collision with Earth in 2052. More observations were done after 2021 QM1 got out of the Sun’s glare and became visible to our telescopes. New data revealed that it’s not on a collision course with our planet. We will even have a good chance to study it in detail during its close flyby.

    More about asteroid surveillance.

    Astronomers Found a Pulsar that Could Be Only 14 Years Old

    A pulsar in a dwarf galaxy 400 million light years away was first seen in 2018. But when astronomers checked archival data, it appeared that the pulsar wasn’t there in 1998’s data. This means that this particular star can be very young. Literally younger than most of you, who are reading this article.

    More about a very young pulsar.

    The Case is Building That Colliding Neutron Stars Create Magnetars

    Magnetars defy comprehension. These exotic objects can have magnetic fields which are hundreds of millions of times more powerful than anything we can generate here on Earth. Astronomers know they’re neutron stars, but they rotate less rapidly than pulsars. But one has been found that spins 750 times a second. It’s believed this is a brand new magnetar and could have only gotten spinning this quickly through the collision of two neutron stars. Maybe this is how magnetars form.

    More about creation of magnetars.

    A New Map of Mars from MRO

    NASA’s Mars Reconnaissance Orbiter has been at the Red Planet since 2006, imaging its surface with a powerful suite of instruments. One of these is the Compact Reconnaissance Imaging Spectrometer (CRISM), which makes maps of minerals on the Martian surface. Unfortunately, CRISM has run out of coolant and can only record a fraction of the data it once could. NASA is releasing a surface mineral map of Mars made up of 51,000 separate images taken by CRISM.

    More about MRO’s map of Mars.

    More Breaking Space News

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  • The Solar System is Stable for at Least the Next 100,000 Years
    by Scott Alan Johnston on July 1, 2022 at 10:43 pm

    It’s nice to have a feel-good story every once in a while, so here’s one to hold off the existential dread: the Earth isn’t likely to get flung off into deep space for at least 100,000 years. In fact, all of the Solar System’s planets are safe for that time frame, so there is good news all around, for you and your favorite planetary body.

    Maybe it’s worth backing up a little bit. The likelihood of Earth, or any planet, being bumped from its orbit is always slim. As Newtonian physics tells us, an object in motion remains in motion unless acted upon by another force – and for something the size of a planet, it would take a significant force to push a planet off track. But there are examples of planetary reshuffling in the Solar System’s own history. One of the most broadly accepted models of Solar System formation, the Nice model, describes how the outer planets migrated early in the Solar System’s history, and would have wreaked havoc on the inner rocky worlds, possibly displacing or even swallowing smaller proto-planets in the process.

    But now, researchers have done the math to show that such a migration is unlikely in the next 100,000 years. Angel Zhivkov and Ivaylo Tounchev from the Department of Mathematics and Informatics at Sofia University in Bulgaria used computer calculations to determine that the planets are likely to remain stable. Their eccentricities (how much their orbit differs from circular) will stay small, as will their inclination (how far above or below the plane of the Solar System they travel). Similarly, the semi-major axes (the radius of the longest part of an elliptical orbit) will not change significantly for any of the planets.

    The Semi Major Axis of a planetary orbit. Image Credit: Sndeep81, Wikimedia Commons.

    Even downgraded dwarf planet Pluto was included in this study, and diehard Pluto fans will be happy to know that it too is likely to do little more than oscillate a bit over the next 100,000 years.

    So what happens after 100,000 years? The farther you go in time, the harder predictions become, as the real Universe is always a little chaotic, but Zhivkov and Tounchev believe that “with simple additional reasonings and evaluations…the Theorem could be proven for one million years.” There’s not likely to be trouble in that timespan either. And, if you’re really worried, all it would take is some additional computing power beyond what was accessible to the researchers, and “the stability of the solar system could be proved for the next five billion years,” they say.

    Of course, the model isn’t perfect. It doesn’t take into account relativistic effects, and the math assumes that the planets are point masses, which, of course, in real life they are not. But perhaps the most glaring omission from the calculation are the millions of smaller bodies in the Solar System: asteroids, comets, and everything in between. On their own, the gravitational effects of these objects are negligible, but as a collective, over billions of years, they certainly could jiggle the planets around a bit. Including them all in the model would be a monumental task, and one with diminishing returns. It’s not something that should keep you awake at night.

    A simulation of all known near-Earth objects as of January 2018. The Solar System is a busy place – luckily, most of the objects are tiny, with plenty of empty space separating them from us and each other. Credit: NASA/JPL-Caltech.

    So, Earthlings, Martians, and Jovians alike: take a breath and enjoy the ride. The next 100,000 years around the Sun are going to be smooth sailing. Don’t forget the sunscreen!

    Learn More:

    If you want to read the paper yourself, the preprint is available on ArXiv.

    Feature Image: True color representation of the planets. Credit: CactiStaccingCrane, Wikimedia Commons.

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  • Most Black Holes Spin Rapidly. This one… Doesn’t
    by Carolyn Collins Petersen on July 1, 2022 at 12:36 am

    A Chandra X-ray Observatory view of the supermassive black hole at the heart of quasar H1821+643. Courtesy NASA/CXC/Univ. of Cambridge/J. Sisk-Reynés et al.
    A Chandra X-ray Observatory view of the supermassive black hole at the heart of quasar H1821+643. Courtesy NASA/CXC/Univ. of Cambridge/J. Sisk-Reynés et al.

    Black holes. They used to be theoretical, up until the first one was found and confirmed back in the late 20th Century. Now, astronomers find them all over the place. We even have direct radio images of two black holes: one in M87 and Sagittarius A* in the center of our galaxy. So, what do we know about them? A lot. But, there’s more to find out. A team of astronomers using Chandra X-ray Observatory data has made a startling discovery about a central supermassive black hole in a quasar embedded in a distant galaxy cluster. What they found provides clues to the origin and evolution of supermassive black holes.

    Two-factor Identification of Black Holes

    If you’re going to study a black hole, particularly a supermassive one, there are a lot of challenges. It turns out every large galaxy has a central monster black hole. So, it’s important to know as much as we can about them. These cosmic behemoths contain millions or even billions of solar masses. They have strong gravitational pulls—and nothing, not even light, can escape their clutches. That affects our ability to look at them and their nearby regions.

    One thing that isn’t quite clear yet: how do these monsters form and evolve? The answer lies partially in two of their characteristics. “Every black hole can be defined by just two numbers: its spin and its mass,” said Julia Sisk-Reynes {Institute of Astronomy (IoA), the University of Cambridge in the U.K), who led a new study of a supermassive black hole some 3.6 billion years away from us. “While that sounds fairly simple, figuring those values out for most black holes has proved to be incredibly difficult.”

    X-raying a Black Hole

    Measuring the masses is difficult, although there are ways to do it. Measuring spin is a real challenge. To learn more about monster black holes, Sisk-Reynes and collaborators used Chandra X-ray Observatory data. They studied observations of the central supermassive black hole engine of the quasar H1821+643 and possibly get its spin rate. It contains 30 billion times the mass of the Sun. (By comparison, the Milky Way’s central supermassive black hole has only about four billion solar masses.)

    Why X-rays? A spinning black hole drags space around with it and allows matter to orbit closer to it than is possible for a non-spinning one. X-ray data shows how fast the black hole spins. Studies of the spectrum of H1821+643 show that its black hole rotation rate is weird, compared to other less massive ones that spin at close to the speed of light. That slower rate for the quasar’s black hole surprised the team.

    This composite image of H1821+643 contains X-rays from Chandra (blue) that have been combined with radio data from NSF's Karl G. Jansky Very Large Array (red) and an optical image from the PanSTARRS telescope on Hawaii (white and yellow). The researchers used nearly a week's worth of Chandra observing time, taken over two decades ago, to obtain this latest result. The supermassive black hole is located in the bright dot in the center of the radio and X-ray emission.
    This composite image of H1821+643 contains X-rays from Chandra (blue) that have been combined with radio data from NSF’s Karl G. Jansky Very Large Array (red) and an optical image from the PanSTARRS telescope on Hawai’i (white and yellow). The researchers used nearly a week’s worth of Chandra observing time, taken over two decades ago, to obtain this latest result. The supermassive black hole is located in the bright dot in the center of the radio and X-ray emission.

    “We found that the black hole in H1821+643 is spinning about half as quickly as most black holes weighing between about a million and ten million suns,” said astronomer Christopher Reynolds (also of the Institute of Astronomy). He is co-author of the paper reporting the results of the Chandra measurements. “The million-dollar question is: why?”

    Black Holes: Origin and Evolution

    The history of H1821+643 could hold the key to understanding its slower spin rate, according to co-author James Matthews (also at the Institute of Astronomy). He suggests that supermassive black holes like the one in H1821+643 likely grew through mergers with other black holes during collisions of their galaxies. It’s well known that galaxy collisions build up larger galaxies over time, and so those same activities (including collisions of dwarf galaxies) are fair game as possible factors.

    It’s also possible that this black hole had its outer disk disrupted in a collision, which sent gas out in random directions during the event. These kinds of activities would affect the spin rate of the black hole—slowing it down, or even torquing it around in an entirely new direction. That means such black holes could show a range of spin rates, depending on their recent histories.

    “The moderate spin for this ultramassive object may be a testament to the violent, chaotic history of the universe’s biggest black holes,” Matthews said. “It may also give insights into what will happen to our galaxy’s supermassive black hole billions of years in the future when the Milky Way collides with Andromeda and other galaxies.”

    For More Information

    Chandra Shows Giant Black Hole Spins Slower Than Its Peers

    Evidence for a moderate spin from X-ray reflection of the high-mass supermassive black hole in the cluster-hosted quasar H1821+643

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  • Tidal Heating Could Make Exomoons Much More Habitable (and Detectable)
    by Matt Williams on June 30, 2022 at 10:50 pm

    Within the Solar System, most of our astrobiological research is aimed at Mars, which is considered to be the next-most habitable body beyond Earth. However, future efforts are aimed at exploring icy satellites in the outer Solar System that could also be habitable (like Europa, Enceladus, Titan, and more). This dichotomy between terrestrial (rocky) planets that orbit within their a system’s Habitable Zones (HZ) and icy moons that orbit farther from their parent stars is expected to inform future extrasolar planet surveys and astrobiology research.

    In fact, some believe that exomoons may play a vital role in the habitability of exoplanets and could also be a good place to look for life beyond the Solar System. In a new study, a team of researchers investigated how the orbit of exomoons around their parent bodies could lead to (and place limits on) tidal heating – where gravitational interaction leads to geological activity and heating in the interior. This, in turn, could help exoplanet-hunters and astrobiologists determine which exomoons are more likely to be habitable.

    The research was conducted by graduate student Armen Tokadjian and Professor Anthony L. Piro from the University of Southern California (USC) and The Observatories of the Carnegie Institution for Science. The paper that describes their findings (“Tidal Heating of Exomoons in Resonance and Implications for Detection“) recently appeared online and has been submitted for publication in the Astronomical Journal. Their analysis was inspired largely by the presence of multiplanet moon systems in the Solar System, such as those that orbit Jupiter, Saturn, Uranus, and Neptune.

    Illustration of Jupiter and the Galilean satellites. Credit: NASA

    In many cases, these icy moons are believed to have interior oceans resulting from tidal heating, where gravitational interaction with a larger planet leads to geological action in the interior. This, in turn, allows for liquid oceans to exist due to the presence of hydrothermal vents at at the core-mantle boundary. The heat and chemicals these vents release into the oceans could make these “Ocean Worlds” potentially habitable – something scientists have been hoping to investigate for decades. As Tokadjian explained to Universe Today via email:

    “In terms of astrobiology, tidal heating may boost the surface temperature of a moon to a range where liquid water can exist. Thus even systems outside the habitable zone may warrant further astrobiological studies. For example, Europa hosts a liquid ocean due to tidal interactions with Jupiter, although it lies outside the Solar System’s ice line.”

    Considering how plentiful “Ocean Worlds” are in the Solar System, it is likely that similar planets and multi-moon systems can be found throughout our galaxy. As Piro explained to Universe Today via email, the presence of exomoons has a lot of important implications for life, including:

    • Large moons like our own can stabilize the planet’s axial tilt, so the planet has regular seasons
    • Tidal interactions can prevent planets from tidally locking with their host star, impacting the climate
    • Moons can tidally heat a planet, helping it maintain a molten core, which has many geological implications
    • When a gaseous planet is in the habitable zone of a star, the moon itself can host life (think of Endor or Pandora)

    In recent decades, geologists and astrobiologists have theorized that the formation of the Moon (ca. 4.5 billion years ago) played a major role in the emergence of life. Our planetary magnetic field is the result of its molten outer core rotating around a solid inner core and in the opposite direction of the planet’s own rotation. The presence of this magnetic field shields Earth from harmful radiation and is what allowed our atmosphere to remain stable over time – and not slowly stripped away by solar wind (which was the case with Mars).

    An amazingly active Io, Jupiter’s “pizza moon,” shows multiple volcanoes and hot spots in this photo taken with Juno’s infrared camera. Credit: NASA/JPL-Caltech /SwRI/ASI/INAF/JIRAM/Roman Tkachenko

    In short, the interactions between a planet and its satellites can affect the habitability of both. As Tokadjian and Piro showed in a previous paper using two candidate exoplanets as an example (Kepler-1708 b-i and Kepler-1625 b-i), the presence of exomoons can even be used to explore the interior of exoplanets. In the case of multi-moon systems, said Tokadjian and Piro, the amount of tidal heating depends on several factors. As Piro illustrated:

    “As a planet raises tides on a moon, some of the energy stored by the deformation is transferred into heating the moon. This process is dependent on many factors, including the interior structure and size of the moon, the mass of the planet, planet-moon separation, and the moon’s orbital eccentricity. In a multi-moon system, the eccentricity can be excited to relatively high values if the moons are in resonance, leading to significant tidal heating.”

    “In Armen’s work, he nicely shows, in analogy to the tidal heating we see for Io around Jupiter, that resonant interactions between multiple moons can efficiently heat exomoons. By ‘resonant,’ we mean the case where the periods of moons obey some integer multiple (like 2 to 1 or 3 to 2) so that their orbits gravitationally ‘kick’ each other regularly.”

    In their paper, Tokadjian and Piro considered moons in a 2:1 orbital resonance around planets of varying size and type (i.e., smaller rocky planets to Neptune-like gas giants and Super-Jupiters). According to their results, the largest tidal heating will occur in moons that orbit rocky Earth-like planets with an orbital period of two to four days. In this case, the tidal luminosity was over 1000 times that of Io, and the tidal temperature reached 480 K (~207 °C; 404 °F).

    Artist’s impression of the view from a hypothetical moon around an exoplanet orbiting a triple star system. Credit: NASA

    These findings could have drastic implications for future exoplanet and astrobiology surveys, which are expanding to include the search for exomoons. While missions like Kepler have detected many exomoon candidates, none have been confirmed since exomoons are incredibly difficult to detect using conventional methods and current instruments. As Tokadjian explained, tidal heating could offer new methods for exomoon detection:

    “First, we have the secondary eclipse method, which is when a planet and its moon move behind a star resulting in a dip in stellar flux observed. If the moon is significantly heated, this secondary dip will be deeper than what is expected from the planet alone. Second, a heated moon will likely expel volatiles like sodium and potassium through volcanism much like the case of Io. Detecting sodium and potassium signatures in the atmospheres of exoplanets can be a clue for exomoon origin.”

    In the coming years, next-generation telescopes like the James Webb (which will be releasing its first images on July 12th) will rely on their combination of advanced optics, IR imaging, and spectrometers to detect chemical signatures from exoplanet atmospheres. Other instruments like the ESO’s Extremely Large Telescope (ELT) will rely on adaptive optics that will allow for Direct Imaging of exoplanets. The ability to detect chemical signatures of exomoons will greatly increase their ability to find potential signs of life!

    Further Reading: arXiv

    The post Tidal Heating Could Make Exomoons Much More Habitable (and Detectable) appeared first on Universe Today.

  • Red Supergiant Stars Bubble and Froth so Much That Their Position in the Sky Seems to Dance Around
    by Carolyn Collins Petersen on June 30, 2022 at 9:59 pm

    Making a 3D map of our galaxy would be easier if some stars behaved long enough to get good distances to them. However, red supergiants are the frisky kids on the block when it comes to pinning down their exact locations. That’s because they appear to dance around, which makes pinpointing their place in space difficult. That wobble is a feature, not a bug of these massive old stars and scientists want to understand why.

    So, as with other challenging objects in the galaxy, astronomers have turned to computer models to figure out why. In addition, they are using Gaia mission position measurements to get a handle on why red supergiants appear to dance.

    Artist’s impression of the red supergiant star Betelgeuse as it was revealed with ESO’s Very Large Telescope. It shows a boiling surface and material shed by the star as it ages. Credit: ESO/L.Calçada
    Artist’s impression of the red supergiant star Betelgeuse as it was revealed with ESO’s Very Large Telescope. It shows a boiling surface and material shed by the star as it ages. Credit: ESO/L.Calçada

    Understanding Red Supergiants

    The population of red supergiants has several common characteristics. These are stars at least eight times the mass of the Sun, and they’re enormous. A typical one is at least 700 to 1,000 times the solar diameter. At 3500 K, they’re much cooler than our ~6000 K star, although measuring those temperatures is tricky. They are super bright in infrared light, but dimmer in visible light than other stars. They also vary in their brightness which (for some of them) may be related to that dancing motion. More on that in a moment.

    If the Sun was a red supergiant, Earth wouldn’t be around. That’s because the star’s atmosphere would have reached out to Mars and swallowed our planet up. The best-known examples of these stellar behemoths are Betelgeuse and Antares. Red supergiants exist throughout the galaxy. There’s a population of them you can see at night in a nearby cluster called Chi Persei. It’s part of the well-known “Double Cluster”.

    The Structure of Red Supergiants

    So, we have this population of stars that don’t behave as expected and don’t lend themselves to easy measurements. Why is that? They’ve expanded so much that they end up with a very low surface gravity. Because of that, their convective cells (the structures that carry heat from inside to the surface) get pretty large. One cell covers as much as 20-30 percent of the radius of the star. That actually “interrupts” the brightness of the star.

    The convection not only moves heat from the inside out, but also helps the star eject material into nearby space. And, we’re not talking small poofs of gas and plasma, either. A red supergiant can send a billion times more mass to space than the Sun does. All that action makes the star appear frothy and like its surface is boiling madly. In essence, it makes the star’s position appear to dance in the sky.

    Red Supergiants in the Grand Scheme of Things

    Red supergiant material becomes part of the chemical “inventory” of galaxies. The elements these stars create go on to become new stars and worlds. So, it helps to get a good understanding of how these stars lose their mass throughout their lives. It’s all part of understanding stellar evolution in the Milky Way and its impact on the cosmic environment. That’s why astronomers want to trace the total mass that these aging stars blow out to space. They also measure the stellar wind velocity and calculate the geometry of the cloud of “star stuff” that envelopes a red supergiant.

    Now, what does this have to do with the dancing action? Well, the boiling of the convection cells and the buildup of a shell of material around the star adds to its variability. That is, it affects its brightness over time.

    One way that astronomers use to determine a star’s exact position is by using its “photo-center”. That’s the center of light of the star. If the star varies in brightness (for whatever reason), that photo-center shifts. It won’t match the barycenter. (That’s the common center of gravity between the star and the rest of its system. It is a component in distance measurements.) In essence, the photo-center varies as the star’s brightness changes. Combined with the action of the huge convection cells, the star appears to dance in space.

    A video of the simulation of a red supergiant surface shows that the constantly changing photosphere of the star (big image) leads to changes in the apparent position of the star’s center (small image at lower left). Credit: A. Chiavassa, Tl Grassi, et al.

    The Dance Changes the Distance Estimate

    The red supergiant “position problem” attracted Andrea Chiavassa (Laboratoire Lagrange, the Exzellenzcluster ORIGINS, and the Max Planck Institute for Astrophysics). She and astronomer Rolf Kudritzki (Munich University of Observatory and the Institute of Hawai’i) and a science team created simulations of the boiling surfaces and variability of red supergiant brightness.

    “The synthetic maps show extremely irregular surfaces, where the largest structures evolve on timescales of months or even years, while smaller structures evolve over the course of several weeks,” said Chiavassa. “This means that the position of the star is expected to change as a function of time.”

    The team compared their model to stars in Chi Persei. That cluster was measured by the Gaia satellite, so the positions of most of its stars are very precise. Well, all but the red supergiants. “We found that the position uncertainties of red supergiants are much larger than for other stars. This confirms that their surface structures change dramatically with time as predicted by our calculations”, explained Kudritzki.

    This change in observable position provides a solution to understanding the shifting positions of red supergiants. That, in turn, presents difficulties in measuring exact distances to many of these stars. The current model also gives clues to the evolution of these objects. But, knowing what’s causing the stars to dance offers a path to a solution when calculating their distances. Future models will help astronomers refine those distances, and provide more insight into what’s happening to these stars as they age.

    For More Information

    Dancing Pattern of Red Supergiants on the Sky

    Probing Red Supergiant Dynamics Through Photo-center Displacements measured by Gaia

    The post Red Supergiant Stars Bubble and Froth so Much That Their Position in the Sky Seems to Dance Around appeared first on Universe Today.

  • This is How You Get Multiple Star Systems
    by Evan Gough on June 30, 2022 at 8:14 pm

    Stars form inside massive clouds of gas and dust called molecular clouds. The Nebular Hypothesis explains how that happens. According to that hypothesis, dense cores inside those clouds of hydrogen collapse due to instability and form stars. The Nebular Hypothesis is much more detailed than that short version, but that’s the basic idea.

    The problem is that it only explains how single stars form. But about half of the Milky Way’s stars are binary pairs or multiple stars. The Nebular Hypothesis doesn’t clearly explain how those stars form.

    Most stars about the same mass as our Sun or larger aren’t single stars. Most are members of multiple star systems, especially binary stars. While the nebular theory explains how single stars form, there are competing theories for how multiple stars form.

    First of all, after a molecular cloud collapses into a star, it forms a rotating disk of gas and dust around the young protostar, called a circumstellar disk. One theory explaining how multiple stars form says that a pair or more of young protostars are fragments of a parent disk that was once much larger. Another theory says that the young protostars form independently, then one captures the other in an orbital arrangement.

    This is an ALMA image of a young protostar, called a T Tauri star. They're less than 10 million years old and are representative of the type of young stars found in stellar nurseries like the Orion Cloud Complex. It shows the disc surrounding the young star, out of which planets will eventually form. The researchers behind this new study examined the dense cores that form young stars like this to find differences between cores that formed multiple stars and those that formed single stars like our Sun. Image Credit: ALMA (ESO/NAOJ/NRAO)
    T Tauri stars are less than 10 million years old and represent the type of young stars found in stellar nurseries like the Orion Cloud Complex. It shows the disc surrounding the young star, out of which planets will eventually form. The researchers behind this new study examined the dense cores that form young stars like this to find differences between cores that formed multiple stars and those that formed single stars like our Sun. Image Credit: ALMA (ESO/NAOJ/NRAO)

    But when stars form inside a molecular cloud, it begins with a dense core inside the cloud. That core initiates the gravitational collapse that gathers enough gas in one place to form a star. The question is, what’s different about some of those cores that cause multiple stars to form versus single stars?

    That’s what astronomers at Hawaii’s James Clerk Maxwell Telescope (JCMT) wanted to understand.

    The JCMT is a 15-meter radio telescope at Mauna Kea Observatory in Hawaii. The telescope’s submillimeter observations allow it to observe the molecular clouds where stars are born. The researchers used it to observe the Orion Molecular Cloud Complex (OMCC), the closest active stellar nursery to Earth, which is still about 1500 light-years away. The OMCC contains two giant molecular clouds (GMCs), Orion A and Orion B. They also used observations from ALMA and Japan’s Nobeyama Telescope.

    The team watched multiple star systems forming in the Orion Complex and made important discoveries about the process. They presented their findings in a paper published in The Astrophysical Journal. The paper is “ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP): How Do Dense Core Properties Affect the Multiplicity of Protostars?” The first author is Qiuyi Luo, a Ph.D. student at Shanghai Astronomical Observatory.

    “During the transition phase from a prestellar to a protostellar cloud core, one or several protostars can form within a single gas core,” the paper stars. “The detailed physical processes of this transition, however, remain unclear.”

    For this study, the team of researchers collected observations of 43 protostellar cores in the Orion molecular cloud complex with the JCMT. Then they used the powerful ALMA telescope to examine the interior structure of the cores.

    This image shows the G205.46-14.56 clump located in the Orion Molecular Cloud Complex. The yellow contours show the dense cores discovered by JCMT, and the zoomed-in pictures show the 1.3mm continuum emission of ALMA observation. These observations give insight into the formation of various stellar systems in dense cores. Image Credit: Qiuyi Luo et al. 2022.
    This image shows the G205.46-14.56 clump located in the Orion Molecular Cloud Complex. The yellow contours show the dense cores discovered by JCMT, and the zoomed-in pictures show the 1.3mm continuum emission of ALMA observation. These observations give insight into the formation of various stellar systems in dense cores. Image Credit: Qiuyi Luo et al. 2022.

    The research shows that about 30% of the 43 dense cores form binary or multiple stars, and the remainder forms only single stars. The astronomers measured and estimated the sizes and masses of the cores. They found that binary/multiple cores have higher densities and masses, although the sizes of all the cores aren’t much different.

    This figure from the study shows the exemplar core G196.92-10.37. (a) is a JCMT image with a Spitzer image superimposed on it. The yellow circle is the zoomed-in region in (b.) (b) shows continuum contour levels. (c) shows ALMA data and also shows that the core is forming three stars: A, B, and C. Image Credit: Qiuyi Luo et al. 2022.
    This figure from the study shows the exemplar core G196.92-10.37. (a) is a JCMT image with a Spitzer image superimposed on it. The yellow circle is the zoomed-in region in (b.) (b) shows continuum contour levels. (c) shows ALMA data and also indicates that the core is forming three stars: A, B, and C. Image Credit: Qiuyi Luo et al. 2022.

    “This is understandable,” said first author Qiuyi Luo. “Denser cores are much easier to fragment due to the perturbations caused by self-gravity inside molecular cores.”

    From there, the team turned to Japan’s 45-meter Nobayama radio telescope. They observed what’s known as the N2H+ J=1-0 molecular line in all 43 dense cores. N2H+ is diazenylium, one of the first ions ever found in interstellar clouds. This molecular line is easily observed through Earth’s atmosphere with fine precision. Astronomers use it to map the density and velocity of the gas in molecular clouds.

    Those observations showed that dense cores that form multiple stars are more turbulent than cores that form single stars.

    This figure from the study shows the Mach number for gas in the dense cores as measured with the N2H+ line. Higher Mach numbers mean more turbulence, and this figure shows that binary and multiple star cores are more turbulent than cores forming single stars. Image Credit: Qiuyi Luo et al. 2022.
    This figure from the study shows the Mach number for gas in the dense cores as measured with the N2H+ line. Higher Mach numbers mean more turbulence, and this figure shows that binary and multiple star cores are more turbulent than cores forming single stars. Image Credit: Qiuyi Luo et al. 2022.

    “These Nobeyama observations provide a good measurement of turbulence levels in dense cores. Our findings indicate that binary/multiple stars tend to form in more turbulent cores,” said Prof. Ken’ichi Tatematsu, who led the Nobeyama observations.

    Lead author Qiuyi Luo summarized the study’s findings in a press release. “In a word, we found that binary/multiple stars tend to form in denser and more turbulent molecular cores in this study.”

    This figure from the study shows the gas velocity in two of the dense cores. Blue indicates lower velocity and red indicates higher velocity. The arrows show the directions of the local increasing velocity gradients, with the lengths indicating their magnitudes. The top core, labelled in orange, is a binary core, and the bottom core labelled in black is a single core. Image Credit: Qiuyi Luo et al. 2022.
    This figure from the study shows the gas velocity in two of the dense cores. Blue indicates lower velocity, and red indicates higher velocity. The arrows show the directions of the local increasing velocity gradients, with the lengths indicating their magnitudes. The top core, labelled in orange, is a binary core, and the bottom core, labelled in black, is a single core. Image Credit: Qiuyi Luo et al. 2022.

    Co-author Sheng-Yuan Liu added, “The JCMT has proven to be a great tool for uncovering these stellar nurseries for ALMA follow-ups. With ALMA providing unprecedented sensitivity and resolution so that we can do similar studies toward a much sample of larger dense cores for a more thorough understanding of star formation.”

    The researchers also found that the stars in each binary or multiple arrangement are usually at very different evolutionary stages. The more evolved protostars are generally further from the center of the dense cores than their younger counterparts. This indicates that as stars evolve, they migrate out of their natal cores.

    This study shows some differences between cores that form single stars versus cores that form binary and multiple stars. But it’s only the beginning: there’s much more to learn and many more questions.

    One of the questions is what role do magnetic fields play in star formation? Star-forming clouds can be highly magnetized. Magnetic fields from the interstellar medium thread their way through star-forming clouds, and astronomers know that magnetic fields can affect the star formation rate. Do they play a role in determining if a single star forms versus multiple stars?

    This figure is from a separate study that simulated the effect of magnetic fields on star-forming regions. The left is a simulated star-forming region without a magnetic field, right is with a magnetic field. Each white circle is a protostar, and red indicates gas moving at high velocities. Without magnetism, the mass collapses into a central region with less outflowing gas. With magnetism, the protostars are more spread out and more gas is escaping. This seems to indicate that magnetic fields inhibit the formation of dense structures. Image Credit: Krumholz and Federrath 2019.
    This figure is from a separate study that simulated the effect of magnetic fields on star-forming regions. The left is a simulated star-forming region without a magnetic field, right is with a magnetic field. Each white circle is a protostar, and red indicates gas moving at high velocities. Without magnetism, the mass collapses into a central region with less outflowing gas. With magnetism, the protostars are more spread out, and more gas is escaping. This seems to indicate that magnetic fields inhibit the formation of dense structures. Image Credit: Krumholz and Federrath 2019.

    “We have yet to look at the effect of magnetic fields in our analysis,” said corresponding author Tie Liu, who was also the lead for the ALMA observations. “Magnetic field may suppress the fragmentation in dense cores, so we are excited to focus the next stage of our research on this area using the JCMT.”

    The authors point out that the low sample size hampers their results. Forty-three dense cores may not be enough data to draw conclusions from, especially because they’re all from the same molecular cloud. The study was also limited by the resolution of the various observatories and telescopes used in the study.

    “Our results could be further tested using future higher spatial and spectral resolution observations toward a more complete dense core sample in various molecular clouds that are in widely different environments,” they conclude.

    More:

    The post This is How You Get Multiple Star Systems appeared first on Universe Today.

  • The Case is Building That Colliding Neutron Stars Create Magnetars
    by Andy Tomaswick on June 30, 2022 at 12:50 pm

    Magnetars are some of the most fascinating astronomical objects. One teaspoon of the stuff they are made out of would weigh almost one billion tons, and they have magnetic fields that are hundreds of millions of times more powerful than any magnetic that exists today on Earth. But we don’t know much about how they form. A new paper points to one possible source – mergers of neutron stars.

    Neutron stars themselves are equally fascinating in their own right. In fact, magnetars are generally considered to be a specific form of neutron star, with the main difference being the strength of that magnetic field. There are thought to be about a billion neutron stars in the Milky Way, and some of them happen to come in binary pairs.

    When they are gravitationally bound to one another, the stars enter a final dance of death, typically resulting in either a black hole or, potentially, one or both of them transforming into a magnetar. That process can take hundreds of millions of years to build up to a certain point when the actual explosion (or collapse) happens. But when it does, it’s spectacular, and a team of researchers thinks they found that that happened only a few weeks before they spotted it.

    UT video describing magnetars.

    More accurately, it happened around 228 million years ago, which is how far away the galaxy it happened in is. However, the light from this spectacular event reached the sensors at Pan-STARRs only a few weeks before it started observing that patch of the sky. And what makes this magnetar stand out from all the others scientists have found is how fast it is spinning.

    Typically, neutron stars rotate thousands of times per minute, making their period on the order of milliseconds. But the magnetars scientists have found are distinct in that their rotational time is much slower, typically only once every two to ten seconds. But GRB130310A, as the new magnetar is now known, has a rotational period of 80 milliseconds, putting it closer to the order of neutron stars than the typical magnetar.

    This discrepancy is probably due to the remarkably young age at which Zhang Binbin and his colleagues found this magnetar. It has yet to complete its rotational slowing, as many other observed magnetars had. But the fact that its rotational period is approaching the rate of neutron stars points to its potential starting point as one of those neutron stars itself.

    Magnetars aren’t the only phenomena that can result from a merger of neutron stars, as described in this UT video.

    That rotational slowing that  GRB130310A is currently undergoing takes thousands of years, but eventually, magnetars fade away and become almost undetectable. An estimated 30 million dead magnetars are floating around the Milky Way, and at least some of those likely started with the same dramatic orbital periods as GRB130310A. 

    Another hint that the new magnetar was spawned from a neutron star merger was the lack of any precursor events that observatories might have picked up. There was no supernova, and no Gamma-ray burst, both of which typically precede the birth of a magnetar. So it appears the researchers happened upon a neutron star merger that they detected almost right as it happened.

    There are other ways to detect neutron star mergers, such as by the gravitational waves they sometimes emit. It is unclear whether any other instrumentation was able to capture this merger to confirm that the event happened as the researchers hypothesize. But if it did, it’s another data point confirming the long-standing idea that magnetars are at least sometimes born from neutron star mergers. And plenty more observations of similar events throughout the universe will be available to help confirm or disprove that theory.

    Learn More:
    B. B. Zhang et al – A hyper flare of a weeks-old magnetar born from a binary-neutron-star merger
    UT – Astronomers Detected a Black Hole-Neutron Star Merger, and Then Another Just 10 Days Later
    UT – Astronomy Jargon 101: Magnetars
    UT – Only 31 Magnetars Have Ever Been Discovered. This one is Extra Strange. It’s Also a Pulsar

    Lead Image:
    Artist’s depiction of a neutron star.
    Credit – ESO / L Calcada

    The post The Case is Building That Colliding Neutron Stars Create Magnetars appeared first on Universe Today.

  • A Dying Star’s Last Act was to Destroy all Its Planets
    by Carolyn Collins Petersen on June 29, 2022 at 11:26 pm

    When white dwarfs go wild, their planets suffer through the resulting chaos. The evidence shows up later in and around the dying star’s atmosphere after it gobbles up planetary and cometary debris. That’s the conclusion a team of UCLA astronomers came to after studying the nearby white dwarf G238-44 in great detail. They found a case of cosmic cannibalism at this dying star, which lies about 86 light-years from Earth.

    If that star were in the place of our Sun, it would ingest the remains of planets, asteroids, and comets out to the Kuiper Belt. That expansive buffet makes this stellar cannibalism act one of the most widespread ever seen.

    “We have never seen both of these kinds of objects accreting onto a white dwarf at the same time,” said lead researcher Ted Johnson, a physics and astronomy graduate of UCLA. “By studying these white dwarfs, we hope to gain a better understanding of planetary systems that are still intact.”

    An artist's view of a white dwarf _a dying star) siphoning off debris from shattered worlds in its planetary system. Courtesy NASA/ESA, Joseph Olmstead (STScI)
    An artist’s view of a white dwarf siphoning off debris from shattered worlds in its planetary system. Courtesy NASA/ESA, Joseph Olmstead (STScI)

    Finding Evidence of Chaos at a Dying Star

    Johnson was part of a team from UCLA, UC San Diego, and the University of Kiel in Germany working to study chemical elements detected in and around the white dwarf atmosphere. They used data from NASA’s retired Far Ultraviolet Spectroscopic Explorer, the Keck Observatory’s High-Resolution Echelle Spectrometer in Hawaii, and the Hubble Space Telescope’s Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph. The team found and measured the presence of nitrogen, oxygen, magnesium, silicon, and iron, as well as other elements.

    The iron is particularly interesting since it makes up the cores of rocky planets like Earth or Mars. Its presence is a clue that terrestrial-type worlds once orbited G238-44. The presence of high amounts of nitrogen implies the system had a pool of icy bodies as well.

    When White Dwarfs Strike

    As stars like the Sun enter very old age, they leave behind burned-out cores called white dwarfs. Over billions of years, these remnants of dying stars slowly cool down. Before they get to that point, however, the actual death throes can be quite violent and messy. That’s when they cannibalize the worlds around them. The discovery of the “leftovers” of those planets, comets, and asteroids, in the atmosphere of G238-44 paints an ominous picture of our solar system’s future.

    The evolution of our Sun as a dying star to become a red giant, then form a planetary nebula, and eventually end up as a white dwarf. Image Credit: ESO/S. Steinhofel
    The evolution of our Sun as a dying star to become a red giant, then form a planetary nebula, and eventually end up as a white dwarf. That evolutionary process also also affects worlds and other objects in its system. Image Credit: ESO/S. Steinhofel

    We can expect our Sun to go through the process starting in about five billion years. First, it will balloon out to become a red giant, swallowing up planets possibly out to the orbit of Earth. Then, it will lose its outer layers, forming what we call a “planetary nebula”. Once all that’s dissipated to space, what’s left is the massive, but tiny white dwarf.

    The whole process will tear apart the solar system, ripping planets to shreds and scattering comets and asteroids. Any of those objects that come too close to the white dwarf Sun will get sucked in and destroyed. The scale of the destruction occurs fairly quickly if G238-44’s example is any clue. This study shows the shocking scale of the chaos. Within 100 million years after it entered its white dwarf phase, the dying star was able to capture and consume material from its nearby asteroid belt and its far-flung Kuiper belt–like regions.

    The slow destruction of G238-44’s planetary system, with the tiny white dwarf at the center, surrounded by a faint accretion disk made up of pieces of shattered bodies falling onto the dead star. Any remaining asteroids form a thin stream of material surrounding the dying star. Larger gas giant planets may still exist in the system, and much farther out is a belt of icy bodies such as comets. The process of gobbling up the leftovers of its worlds commenced shortly after the star entered white dwarf phase. Courtesy: NASA, ESA, Joseph Olmsted (STScI)
    The slow destruction of G238-44’s planetary system, with the tiny white dwarf at the center, surrounded by a faint accretion disk made up of pieces of shattered bodies falling onto the dead star. Any remaining asteroids form a thin stream of material surrounding the dying star. Larger gas giant planets may still exist in the system, and much farther out is a belt of icy bodies such as comets. The process of gobbling up the leftovers of its worlds commenced shortly after the star entered its white dwarf phase. Courtesy: NASA, ESA, Joseph Olmsted (STScI)

    What Else This White Dwarf Reveals

    Not only does this finding show what’s in our future, but it also supplies interesting insight into how other systems form. It offers clues to what they contain, and a peek at our own solar system’s past. For example, astronomers think that icy objects crashed into dry, rocky planets in our own infant solar system. That’s in addition to the rocky materials that helped create our planet. For G238-44, that means an interesting amalgamation of stuff from a variety of regions and the evidence shows it.

    “The best fit for our data was a nearly two-to-one mix of Mercury-like material and comet-like material, which is made up of ice and dust,” Johnson said. “Iron metal and nitrogen ice each suggest wildly different conditions of planetary formation. There is no known solar system object with so much of both.”

    A Dying Star Gives Other Clues

    The death of this sun-like star and its penchant for gobbling up debris has another interesting twist. Billions of years ago, comets and asteroids likely delivered water to our planet, sparking the conditions necessary for life. According to Benjamin Zuckerman, UCLA professor of physics and astronomy, the combo of icy and rocky material detected raining onto G238-44 shows that other planetary systems may have icy reservoirs (like the Kuiper Belt and Oort Cloud). That’s in addition to rocky bodies such as Earth and the asteroids.

    “Life as we know it requires a rocky planet covered with a variety of volatile elements like carbon, nitrogen, and oxygen,” Zuckerman said. “The abundances of the elements we see on this white dwarf appear to have come from both a rocky parent body and a volatile-rich parent body—the first example we’ve found among studies of hundreds of white dwarfs.”

    It’s intriguing to think that our own Sun could be doing the same thing in a few billion years. Perhaps some future astronomer on a planet a few dozen light-years away will do the same study that Johnson and his team did—and spot the remains of Earth in the white dwarf Sun’s dying glow.

    For More Information

    Dead Star’s Cannibalism of its Planetary System is the Most Far-Reaching Ever Witnessed

    Dead Star Caught Ripping Up Planetary System

    The post A Dying Star’s Last Act was to Destroy all Its Planets appeared first on Universe Today.

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