Jase1        Posted at 2023-05-08 17:13:28(81Wks ago) Report Permalink URL | ||
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|  Astronomers used NASA’s James Webb Space Telescope to image the warm dust around a nearby young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of our solar system in infrared light. But to their surprise, the dusty structures are much more complex than the asteroid and Kuiper dust belts of our solar system. Overall, there are three nested belts extending out to 14 billion miles (23 billion kilometers) from the star; that’s 150 times the distance of Earth from the Sun. The scale of the outermost belt is roughly twice the scale of our solar system's Kuiper Belt of small bodies and cold dust beyond Neptune. The inner belts – which had never been seen before – were revealed by Webb for the first time. The belts encircle the young hot star, which can be seen with the naked eye as the brightest star in the southern constellation Piscis Austrinus. The dusty belts are the debris from collisions of larger bodies, analogous to asteroids and comets, and are frequently described as 'debris disks.' “I would describe Fomalhaut as the archetype of debris disks found elsewhere in our galaxy, because it has components similar to those we have in our own planetary system,” said András Gáspár of the University of Arizona in Tucson and lead author of a new paper describing these results. “By looking at the patterns in these rings, we can actually start to make a little sketch of what a planetary system ought to look like — if we could actually take a deep enough picture to see the suspected planets.” The Hubble Space Telescope and the Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt. However, none of them found any structure interior to it. The inner belts have been resolved for the first time by Webb in infrared light. “Where Webb really excels is that we're able to physically resolve the thermal glow from dust in those inner regions. So you can see inner belts that we could never see before,” said Schuyler Wolff, another member of the team at the University of Arizona. Hubble, ALMA, and Webb are tag-teaming to assemble a holistic view of the debris disks around a number of stars. “With Hubble and ALMA, we were able to image a bunch of Kuiper Belt analogs, and we've learned loads about how outer disks form and evolve,” said Wolff. “But we need Webb to allow us to image a dozen or so asteroid belts elsewhere. We can learn just as much about the inner warm regions of these disks as Hubble and ALMA taught us about the colder outer regions.” These belts most likely are carved by the gravitational forces produced by unseen planets. Similarly, inside our solar system Jupiter corrals the asteroid belt, the inner edge of the Kuiper Belt is sculpted by Neptune, and the outer edge could be shepherded by as-yet-unseen bodies beyond it. As Webb images more systems, we will learn about the configurations of their planets. Fomalhaut's dust ring was discovered in 1983 in observations made by NASA's Infrared Astronomical Satellite (IRAS). The existence of the ring has also been inferred from previous and longer-wavelength observations using submillimeter telescopes on Mauna Kea, Hawaii, NASA’s Spitzer Space Telescope, and Caltech's Submillimeter Observatory. “The belts around Fomalhaut are kind of a mystery novel: Where are the planets?” said George Rieke, another team member and U.S. science lead for Webb's Mid-Infrared Instrument (MIRI), which made these observations. "I think it's not a very big leap to say there's probably a really interesting planetary system around the star.” “We definitely didn't expect the more complex structure with the second intermediate belt and then the broader asteroid belt,” added Wolff. “That structure is very exciting because any time an astronomer sees a gap and rings in a disk, they say, ‘There could be an embedded planet shaping the rings!’” Webb also imaged what Gáspár dubs "the great dust cloud" that may be evidence for a collision occurring in the outer ring between two protoplanetary bodies. This is a different feature from a suspected planet first seen inside the outer ring by Hubble in 2008. Subsequent Hubble observations showed that by 2014 the object had vanished. A plausible interpretation is that this newly discovered feature, like the earlier one, is an expanding cloud of very fine dust particles from two icy bodies that smashed into each other. The idea of a protoplanetary disk around a star goes back to the late 1700s when astronomers Immanuel Kant and Pierre-Simon Laplace independently developed the theory that the Sun and planets formed from a rotating gas cloud that collapsed and flattened due to gravity. Debris disks develop later, following the formation of planets and dispersal of the primordial gas in the systems. They show that small bodies like asteroids are colliding catastrophically and pulverizing their surfaces into huge clouds of dust and other debris. Observations of their dust provide unique clues to the structure of an exoplanetary system, reaching down to earth-sized planets and even asteroids, which are much too small to see individually. Credits RELEASE: NASA, ESA, STScI MEDIA CONTACT: Ray Villard Space Telescope Science Institute, Baltimore, Maryland Christine Pulliam Space Telescope Science Institute, Baltimore, Maryland | |
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| BeowulfPosted at 2023-05-08 17:30:59(81Wks ago) Report Permalink URL | ||
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|  In this colorful Picture of the Week we see a portion of the Gum 10 nebula through the eyes of ESO’s Very Large Telescope in Chile. Gum 10 was discovered by the Australian astronomer Colin Stanley Gum, who in 1955 published a catalogue with more than 80 similar diffuse nebulae.  The energetic ultraviolet radiation from the hot blue stars in Gum 10 ionise the gas in the nebula, stripping electrons away from their atoms. When these electrons combine again with the atoms, they emit light at very specific colours or wavelengths. The red shade in this image comes from hydrogen, the most abundant element in the Universe. The dark areas are dense clouds of dust that partially block our view of the objects behind them. This image, taken with the FORS2 instrument, was created as part of the ESO Cosmic Gems programme, an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive. Credit: ESO & Beowulf  | |
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| Jase1Posted at 2023-05-09 14:29:23(81Wks ago) Report Permalink URL | ||
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| Strange worlds, here we come. BY JACKIE APPEL MAY 5, 2023  Astronomers have invented a new method for searching out and spotting exoplanets. It combines two previous methods—astrometry and direct imaging—to narrow down targets before confirming the presence of a planet. Researchers hope this will allow the search for other worlds to become more efficient and effective. Exoplanets are undeniably fascinating. Other world around other stars that could hold the answers to all kinds of large-scale space questions—including, potentially, whether or not we are alone in the universe. Since finding the first exoplanets in 1992, researchers have spotted over 5000 of these extraterrestrial worlds, and they have their sights set on finding many, many more. But just because we’ve found so many so far doesn’t mean it’s been easy. It has taken a lot of work to distill effective methods for spotting these cosmically tiny bodies. And researchers believe they have found one of the most effective methods yet—one that actually combines two methods together. Generally, exoplanets are found through one of five methods. There’s the transit method, which allows researchers to spot planets when they block light by orbiting in front of their host star. There’s the radial velocity method, where you can spot planets by measuring the gravitational effect they have on their stars. There’s gravitational microlensing, where a second star acts as a telescope and causes a flash of light if an exoplanet is present. There’s astrometry, where scientists look for how an exoplanet causes a host star to move in relation to other stars. And there’s direct imaging, where you just… see an exoplanet directly. Usually, all of those methods are used on their own. They’ve been successful, but they often involve casting a very wide net and seeing what gets trapped. But recently, astronomers were able to combine astrometry and direct imaging together and find an exoplanet. They used astrometry to narrow down what stars might be good candidates to search for exoplanets, and then direct imaged those stars to see if the planets were in fact present. This seems like an obvious thing to do—narrow down the hunt and then be able to target potential exoplanet sites more efficiently. But it requires two huge sets of data—one of set of astronomy data and another corresponding set of direct imaging data. Getting access to that kind of data is tricky when everyone wants to use the telescopes all the time for every project. So, the team started with what they already had. They went through over 25 years of astrometric data that had already been gathered by the ESA’s Gaia and Hipparcos missions. Once they had used that data to identify their targets, they reserved time on the Subaru Telescope (located on top of Maunakea in Hawai’i) to follow up with direct imaging. And so far, it has worked in at least one instance. The team discovered the existance of HIP99770b, a hot Jupiter-like planet orbiting around the star HIP99770. HIP99770 would usually be quite difficult to find exoplanets around, as it’s twice the size of our Sun, and stars that massive often block out a lot of what’s around them. In the future, the team hopes that they can use their technique to find even more exoplanets even more efficiently. Especially considering that this approach, when it works, does eventually provide direct imaging data. Direct imaging data is critical for analyzing the temperatures, characteristics, and atmospheres of far-off worlds. Combining new techniques with new tech like the James Webb Space Telescope and the upcoming Nancy Grace Roman Telescope—who knows how many new and exciting worlds we’ll find. | |
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| Jase1Posted at 2023-05-09 14:43:37(81Wks ago) Report Permalink URL | ||
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| Hubble spies a rare galaxy filled with stunning light  By Joshua Hawkins | May 6, 2023 | 11:10 AM Newer telescopes like the James Webb will one day outpace the Hubble Space Telescope, which is over 30 years old. For now, though, NASA and the ESA’s old-school observatory continues to wow us with brilliant spectacles captured in space, like Hubble’s recent image of NGC 5283. NGC 5283 is a lenticular galaxy found in the Draco constellation. It’s situated very close to the northern celestial pole, according to TheSkyLive. That means it’s very visible from the northern hemisphere throughout most of the year. What really makes NGC 5283 so special, though, is that it is home to an AGN. AGNs, or active galactic nuclei, are extremely bright regions at the heart of a galaxy where a supermassive black hole also exists. AGNs form when the dust and gas from the galaxy fall into the black hole at the center, releasing intense heat and light that can be seen far across the universe. And Hubble’s image of NGC 5283 showcases just how bright these AGNs can be.  Image source: NASA, ESA, A. Barth (University of California – Irvine), and M. Revalski (STScI); Processing: Gladys Kober (NASA/Catholic University of America) Galaxies that contain AGNs aren’t uncommon. However, those that are bright, but not too bright — like the one seen in NGC 5283 — are known as Seyfert galaxies. These galaxies stand out because of the bright light they emit. But, as you can see in this latest Hubble image of NGC 5283, the AGN isn’t bright enough to hide the rest of the galaxy. Only 10 percent of galaxies with AGNs are Seyfert galaxies, making them pretty rare. Galaxies like the one pictured above are special because they are a great resource for astronomers investigating the physics behind AGNs, black holes, and even the structure of the AGN’s host galaxy structure. Hubble recently captured a photo of the core of another Seyfert galaxy known as NGC 4395. Learning more about these rare galaxies can teach astronomers a lot. And Hubble’s observations of galaxies like NGC 5283 make that learning possible. Additionally, they also make for spectacular eye candy for space lovers who enjoy getting to see more of our universe with every image release. | |
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| Jase1Posted at 2023-05-10 09:09:05(81Wks ago) Report Permalink URL | ||
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|  Exoplanet Mystery The Space Telescope Science Institute announced this week that NASA's James Webb Space Telescope has detected water vapor near a rocky exoplanet that is highly unlikely to have an atmosphere. It's a startling discovery that raises more questions than it can answer. For instance, does the presence of water vapor indicate that the rocky exoplanet dubbed GJ 486 b has an atmosphere — or could the vapor be coming from the planet's much cooler host star? It's a particularly intriguing finding, since to date, no rocky planet of this sort has been found to definitively have an atmosphere. And regardless, the Webb just keeps delivering the goods. Water Works GJ 486 b orbits its host star every 1.5 Earth days, which means it's far too close to be within the star's habitable zone, a region where the presence of liquid water is theoretically possible. That also means it's incredibly hot, with experts estimating its surface temperature to be around 800 degrees Fahrenheit. This kind of heat makes the existence of an atmosphere unlikely, unless it's somehow able to continually replenish itself as its nearby host star blasts it with radiation. Nonethless, the Webb's Near-Infrared Spectrograph detected signs of water vapor, as detailed in a new paper accepted for publication in The Astrophysical Journal Letters. But the authors of the study warn that there's still a chance that the water vapor may have emanated from the much cooler host star, not the planet. Exoplanet Breakthrough However, if astronomers do find more evidence that the exoplanet has an atmosphere, it would be groundbreaking. "Water vapor in an atmosphere on a hot rocky planet would represent a major breakthrough for exoplanet science," Kevin Stevenson, the principal investigator on the recent study and a staff astronomer at Johns Hopkins University's Applied Physics Laboratory, said in the statement. "But we must be careful and make sure that the star is not the culprit," he added. Fortunately, the Webb telescope's other instruments will soon have a chance to have a closer look at the mysterious rocky planet. "It’s joining multiple instruments together that will really pin down whether or not this planet has an atmosphere," Stevenson explained. | |
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| GarthockPosted at 2023-05-10 12:06:28(81Wks ago) Report Permalink URL | ||
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| I wanted to take a minute to personaly thank Beowulf and Jase1 for all the hard work in this forum. I have posted several stories myself so I know how time consuming it can be to put them together. I absolutely love reading this information. Great work guys. This is just another example of why TGx is the greatest place ever. | |
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| BeowulfPosted at 2023-05-10 17:58:02(81Wks ago) Report Permalink URL | ||
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|  Two stars shine through the centre of a ring of cascading dust in this image taken by the NASA/ESA Hubble Space Telescope. The star system is named DI Cha, and while only two stars are apparent, it is actually a quadruple system containing two sets of binary stars. As this is a relatively young star system it is surrounded by dust. The young stars are moulding the dust into a wispy wrap. The host of this alluring interaction between dust and star is the Chamaeleon I dark cloud — one of three such clouds that comprise a large star-forming region known as the Chamaeleon Complex. DI Cha's juvenility is not remarkable within this region. In fact, the entire system is among not only the youngest but also the closest collections of newly formed stars to be found and so provides an ideal target for studies of star formation. Credit: ESA/Hubble & NASA & Beowulf Acknowledgement: Judy Schmidt | |
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| Jase1Posted at 2023-05-10 20:01:38(81Wks ago) Report Permalink URL | ||
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|  Venus changes appearance quite dramatically as it orbits the Sun. It’s now approaching 50% lit (dichotomy). Venus is an inferior planet. This doesn’t mean it’s a lesser world than ours, it’s simply a reference to the size of its orbit. Inferior planets have smaller orbits than Earth, superior planets larger orbits. Mercury and Venus are inferior planets, the rest are superior. Inferior planets are interesting to observe as their apparent sizes wax and wane noticeably over time and they show a full set of phases. In 2023, Venus reaches greatest eastern elongation on 4 June, appearing 45.4° to the east of the Sun and brilliant in the evening twilight. The planet should appear at 50% phase, known as dichotomy, on this date. This means that May is a great chance to observe Venus before it fades.  The run up to dichotomy, say from 10 days before, is a good time to start making phase estimates and they’re really easy to do. Simply observe Venus through the eyepiece, noting whether the planet’s terminator is straight or curved. If straight, this is dichotomy. If curved, estimate how far across the diameter of Venus – at right angles to the terminator – the terminator extends. As an example, if the terminator stretched one-third across the diameter of Venus, this would be a 33% phase. Starting to observe early gives you more experience at making accurate assessments.  It’s easy to look and record ‘50%’ at a first glance, but is it really 50% or perhaps a little above or below that? Why bother to do this? Surely the geometric position of Venus will give a precise and predictable value for its phase? Actually, this is not the case. The planet’s thick atmosphere interferes with the apparent phase, giving rise to the ‘phase anomaly’, an effect that makes dichotomy appear earlier than it should when Venus is in the evening sky. Last edited by Jase1 on 2023-05-10 20:14:00 | |
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| Jase1Posted at 2023-05-11 11:24:10(81Wks ago) Report Permalink URL | ||
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|  Left, an image of Earth from the DSCOVR-EPIC camera. Right, the same image degraded to a resolution of 3 x 3 pixels, similar to what researchers will see in future exoplanet observations for the closest exoplanets. If we were to build a telescope capable of obtaining ~60-70 micro-arc-second resolution, we'd be able to image an Earth-like planet at this level at the distance of Alpha Centauri. Even with a single pixel, however, a tremendous amount of science could be gleaned. Credit: NOAA/NASA/Stephen Kane It’s hard to imagine, but back in 1990 the year that the Hubble Space Telescope was launched we had yet to discover a single planet beyond the ones within our own Solar System. We were fairly certain they existed, but we didn’t know if they were rare, common, or everywhere. We didn’t know whether rocky planets or gas giants were “normal” planets, or whether there were other types that our own Solar System doesn’t have. And for better or for worse, we operated under the assumption that our Solar System was relatively typical, and that its structure, of inner, rocky planets, an asteroid belt, gas giants, and a Kuiper belt and Oort cloud beyond them would be the template for most, if not all, other planetary systems. What a wild ride the last ~30 or so years have been, and how much they turned our assumptions on their heads. With over 5000 exoplanets now under our belts, and many other protoplanetary disks (where planets form) having been directly imaged, we now realize that much of what we initially thought was entirely too presumptive of us, and that nature is full of surprises. Here are 10 planetary facts that would’ve surprised practically every working astronomer back in 1990, and might still surprise you today!  This color-coded map shows the heavy element abundances of more than 6 million stars within the Milky Way. Stars in red, orange, and yellow are all rich enough in heavy elements that they should have planets; green and cyan-coded stars should only rarely have planets, and stars coded blue or violet should have absolutely no planets at all around them. Note that the central plane of the galactic disk, extending all the way into the galactic core, has the potential for habitable, rocky planets. Credit: ESA/Gaia/DPAC; CC BY-SA 3.0 IGO 1.) Not every star can have them. One of the first surprises that awaited exoplanet scientists came when the Kepler mission first began examining a large field of over 100,000 stars, looking for planetary transits. When a planet passes in front of its parent star, it blocks a fraction of the star’s light. As multiple orbits and multiple transits build up, we can better pin down the orbital distance and physical size of the exoplanet. Initially, based on the number of stars we were looking at and the geometric chances of having a transit observable from our particular line-of-sight, it looked like perhaps ~100% of stars would have planets. But it turns out that this isn’t the case. When we classify stars by metallicity, or the percentage of elements heavier than hydrogen-and-helium within the star, there’s a clear drop-off in planetary abundances. Practically all stars with 25% or more of the heavy elements found in the Sun have planets, only a fraction stars with between 10-25% of the Sun’s heavy elements have planets, and only two or three stars with under 10% of the Sun’s heavy elements have planets at all. Unless you form from material that’s been sufficiently enriched by prior generations of stars, your star isn’t likely to have planets.  When we take into account all of the nearly 5000 exoplanets known at the start of 2022, we can see that the greatest number of planets can be found in between the sizes of Earth (at -1.0 on the x-axis) and Neptune (at -0.5 on the x-axis). However, that does not mean that those worlds are the most abundant, nor that they’re even, as we’ve long been calling them, legitimate “super-Earth” worlds. However, the gap between Neptune-like and Jupiter-like worlds is real; we do not know why there are so few of them. Credit: Open Exoplanet Catalogue 2.) Super-Neptunes (or Mini-Saturns) are rare. We knew, from our own Solar System, that gas giant planets came in at least two different sizes: about four times Earth’s radius, like Neptune and Uranus, and about ten times Earth’s radius, like Jupiter and Saturn. But what else would we find? Would these sizes of worlds be common or rare? Would there be large numbers of gas giant planets found with properties unlike those found in our Solar System, like super-Jupiters, “tweeners” that were in between Neptune and Saturn in size, or mini-Neptunes? It turns out that both Jupiter-sized and Neptune-sized planets are very common, with mini-Neptunes also being even more common than Neptunian worlds. But in between the sizes of Neptune and Saturn are very few planets at all, suggesting that there’s some physical reason why planets tend to avoid forming with sizes between 5-and-9 Earth radii. That reason is still under investigation, but it’s fantastic to know that Neptunes and Jupiters are common, while in-between worlds aren’t! 3.) Ultra-distant gas giants are fairly common. Here in our own Solar System, there’s big “cliff” out beyond 30 times the Earth-Sun distance, or 30 astronomical units (AU). We have eight major planets interior to that distance, but none that are even as large as the smallest planet, Mercury, beyond that distance. But around many stars, there are giant planets located a great distance away: 50 AU, 100 AU, or even several hundred AU away from the main star in their system. Some of these planets are so large that their cores exceed 1 million K in temperature, enabling them to fuse deuterium and become brown dwarfs, while others fall below that mass threshold and instead only generate infrared light, similar to Jupiter. These systems, like HR 8799 (above), are some of the best systems for direct imaging, and have revealed to us many directly imaged exoplanets thus far. When a gravitational microlensing event occurs, the background light from a star-or-galaxy gets distorted and magnified as an intervening mass travels across or near the line-of-sight to the star. The effect of the intervening gravity bends the space between the light and our eyes, creating a specific signal that reveals the mass and speed of the intervening object in question. With enough technological advances, microlensing by rogue supermassive black holes could be measured. Credit: Jan Skowron/Astronomical Observatory, University of Warsaw 4.) Many planets are orphans, without a parent star. In this Universe, what you see isn’t what you get; it’s only representative of the fraction of what you got that survived until the present day. This is true in our Solar System, where many now think that there was a 5th gas giant in our early history that got ejected long ago, and it’s true elsewhere throughout the Universe as well. Some planets remain with their parent stars, others are ejected and roam the Universe as orphan (or rogue) planets, and others very likely come into existence in star-forming regions around clumps of matter that were too low in mass to form a star. Fortunately, a novel method has begun to reveal these rogue planets: gravitational microlensing. As these planets travel through the galaxy, they’ll inevitably pass through our line-of-sight to one or more stars, and when they do, their gravity will bend, distort, and temporarily magnify the light from one of those co-aligned stars. That characteristic microlensing signal has been observed several times, revealing these otherwise invisible orphan planets. With improved observatories and greater wide-field continuous imaging, microlensing may someday reveal more total exoplanets than all other methods combined.  Like many “hot Jupiter” planets, WASP-96b transits in front of its parent star, blocking up to ~1.5% of the parent star’s light when it does. The portion of the starlight that filters through the exoplanet’s atmosphere, during a transit event, is what enables JWST to perform transit spectroscopy and to reveal its atmospheric contents. Hot exoplanets are the easiest type to detect. Credit: NASA, ESA, CSA, and STScI 5.) Ultra-hot planets are the easiest to detect. When it comes to our Solar System, Mercury is the closest planet to our Sun, with an orbit of just 88 days and a maximum daytime temperature of over 800 °F (427 °C). But some of the exoplanets that we’ve found have temperatures of several thousands of degrees, and orbit their parent stars in only a handful of days or even in a matter of hours. It turns out there’s good reason for this: the two methods we use, the radial velocity method (where we measure the “wobble” of a star due to the gravitational effects of an orbiting planet) and the transit method (where we measure the periodic dimming of the parent star as the orbiting planet blocks its light) are both biased towards planets that orbit extremely close to their parent stars. While the first discovered exoplanets were hot and massive, we’ve now discovered a great number of planets of all masses that are very close to their parent stars. That’s not because they’re super common, but because fast-moving planets lead to more dramatic changes in their parent star’s motion and allow us to observe greater numbers of transits in the same amount of observing time. It’s not worth taking a second look at the stars we’ve monitored for evidence of additional hot planets; we’ve probably already seen most of them in the fields of view where we’ve looked.  [color=blue]A wide variety of telescopes have looked at the Fomalhaut system in a variety of wavelengths from both the ground and in space. Only JWST, so far, has been able to resolve the inner regions of the dusty debris present in the Fomalhaut system. Credit: NASA, ESA, CSA, A. Gáspár (University of Arizona) et al., Nature Astronomy, 2023 6.) Long after the planet-forming gas is gone, dusty debris remains. This one was a bit of a puzzle that’s only been unveiled extremely recently. We’ve known for a long time that planet-formation occurs very quickly, and is only possible as long as gas remains around a young star. Once that protoplanetary disk evaporates, planet-formation is complete. Dust, on the other hand, is produced whenever two bodies collide, and can be caused by comet storms, asteroid collisions with one another or with rocky bodies, or several other violent events. But while the gas is all gone after only perhaps 10-20 million years around a newly formed star, the dust can persist for several hundred million years (and perhaps even a billion or more) all throughout stellar systems. While a number of systems have exhibited dust within the analogue of their Kuiper belts, recent observations have shown some big surprises, including: dust found all throughout the inner disk-like region of a stellar system, an intermediate ring of dust between the asteroid belt-like and Kuiper belt-like regions of a stellar system, and systems with up to hundreds of times the amount of dust present in our own Solar System. These clues add up to a tantalizing possibility: maybe our own Solar System, during the early bombardment period, was once a dust-rich system, too.  This image of the dusty debris disk surrounding the young star Fomalhaut is from Webb’s Mid-Infrared Instrument (MIRI). It reveals three nested belts extending out to 14 billion miles (23 billion kilometers) from the star. The inner belts – which had never been seen before – were revealed by Webb for the first time. Labels at left indicate the individual features. At right, a great dust cloud is highlighted and pullouts show it in two infrared wavelengths: 23 and 25.5 microns. Credit: NASA, ESA, CSA; Processing: A. Gáspár (University of Arizona) &Alyssa Pagan (STScI) 7.) Asteroid belts and Kuiper belts are just the tip of the iceberg. We initially thought that an asteroid belt and a Kuiper belt would make sense, and might even be universal properties for stellar systems. After all, the different types of ices that form in space all have their own melting/boiling/sublimation points, and that creates a series of what are known as “frost lines,” or places on the border of where ice of a specific species (water-ice, dry ice, methane ice, nitrogen ice, etc.) can or cannot exist around a star. These lines should correspond to where a belt of asteroids forms, in between any interior and exterior planets. Similarly, there should be a collection of small planetesimals left over out beyond the final planet in a system: a Kuiper belt. So why, as we just observed around Fomalhaut, are we seeing a third belt at intermediate distances? Are there other systems that have more than a Kuiper belt and an asteroid belt, and what sort of physical formation mechanisms drive them into existence? Is our Solar System even common in this regard, or are multiple (perhaps even more than three) belts the norm? We’re truly right at the scientific frontiers here, and this is one discovery that was entirely unexpected.  Although exoplanets have been found in trinary systems before in recent years, most of them orbit either close in to a single star or in intermediate orbits around a central binary, with the third star much farther away. GW Orionis is the first candidate system to have a planet orbiting all three stars at once. About 35% of all stars are in binary systems and another 10% are in trinary systems; only about half of stars are singlets like our Sun. Credit: Caltech/R. Hurt (IPAC) 8.) Multi-star systems can have planets nearly as easily as singlet stars. For a long time, the idea of a Tatooine-like system, where a planet would observe multiple Sun-like stars in their daytime sky, was treated as a physical impossibility. The rationale was that the gravitational three-body problem would render any planet that orbited with multiple large masses nearby would eventually be ejected, rendering such systems what we call in the physics community “dynamically unstable.” And while this is technically true, the timescale for that instability can be several tens of billions of years: longer than the age of the Universe. For every pair of orbiting stars, there are three regions that are quasi-stable: close in orbit around the primary (larger mass) star, close in orbit around the secondary (lower mass) star, or far away from the center-of-mass of both stars. We’ve now found exoplanets that fall into all three of these categories, leading to the understanding that except for a few gravitationally unstable regions set by the relative masses and distances between the stars in a single system, there are plenty of places where planets can stably orbit over the lifetime of a stellar system. In time, we may yet find that the same percentage of multi-star systems are home to planets as singlet-star systems are.  The CHEOPS mission discovered three planets around the star Nu2 Lupi. The innermost planet is rocky and contains only a thin atmosphere, while the second and third planets discovered have large, volatile-rich envelopes. Although some are still calling them super-Earths, it’s very clear that not only are they not rocky, but most of the planets we call super-Earths are not like Earth at all in any meaningful way. Credit: ESA/CHEOPS collaboration 9.) You can only be slightly more massive than Earth and still be rocky and life-friendly. We really jumped to a premature conclusion the first time we discovered an exoplanet with a mass-and-radius that was larger than Earth’s but smaller than Neptune’s: we called them super-Earth worlds. While that’s a tempting way to think about these worlds, it should be equally tempting to think of them as mini-Neptunes, as our simple methods of exoplanet detection have not yet reached the sensitivity to measure and characterize the atmospheres of these worlds. If they’re thin and have rocky surfaces, we’d expect them to be Earth-like; if they’re thick and have large, volatile gas envelopes before you ever reach a solid surface, we’d expect them to be Neptune-like. As measurements of the combination of exoplanet mass, exoplanet radius, and the exoplanet temperature (based on distance from its primary parent star) show, you can only be about ~30% larger and about ~2x as massive as Earth before you transition into a Neptune-like world, as it becomes very easy to hold onto volatile gases with only a little bit more mass than a planet like Earth has. There are exceptions to this general rule, but the exceptions are largely found among very hot worlds whose volatiles are easily boiled and evaporated away. All the while that we’ve been wondering where our Solar System’s “super-Earths” are, the answer has been right under our noses: we are nearly as “super” as an Earth-like planet can get.  Ideally, a new space telescope, between the proposed capabilities of HabEx and LUVOIR (shown here), will be large enough to image a large number of Earth-like exoplanets directly, while still having the desired properties to keep it on-budget and not require the development of wholly new, untested technologies. This observatory, known as Habitable World Observatory, will be NASA’s next flagship mission after the Nancy Roman space telescope. Credit: NASA/GSFC, LUVOIR concept 10.) The exoplanet holy grail, of directly imaging Earth-sized planets in the so-called Habitable Zone, is finally within reach. This is a big one, and it’s finally coming. We’ve often dreamed of what an appropriately advanced alien civilization would see if they looked at Earth from afar, and how they’d tell our planet is inhabited. As the planet rotated on its axis, they would see evidence for clouds, oceans, and variable continents. As the seasons changed, they would see icecaps grow and retreat while the continents greened and browned. And if they could measure our atmospheric contents, they would see gas levels change in a way that indicated that we were not only an inhabited world, but that a technologically advanced species lived here. With the upcoming NASA flagship mission in either the 2030s or 2040s known as Habitable Worlds Observatory headed our way, we’re going to meet that goal: not for Earth, but for any Earth-like planets that happen to be located around the ~20 or so nearest star systems to our own. The combination of having a space-based telescope that’s sufficiently large, with sufficiently advanced instruments, and with an unprecedentedly efficient coronagraph can finally reveal the nearest rocky worlds to us directly, and measure their atmospheres for signs of life, including intelligent life. The great dream of 20th century astronomers will come to fruition in just another 15-20 years, and humanity just might reap the ultimate rewards: getting an affirmative answer to the question of “are we alone in the Universe?” | |
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| hayzee56Posted at 2023-05-11 11:48:41(81Wks ago) Report Permalink URL | ||
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| What a great and interesting and informative post. Thanks so much Jase1 | |
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| Jase1Posted at 2023-05-11 18:24:50(81Wks ago) Report Permalink URL | ||
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Last edited by Jase1 on 2023-05-11 20:35:55 | |
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... I am still after miok's Easter Banner Eggs | BeowulfPosted at 2023-05-12 14:02:14(80Wks ago) Report Permalink URL | ||
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|  The telescope peeking out from its dome is the 1.52-metre telescope at La Silla Observatory. Being over 55 years old, the 1.52-metre is one of the oldest telescopes at ESO and it has participated in laying the foundation for many areas of astronomical research. Being a special telescope in many ways, it also has a twin, the 1.52-metre telescope at the Observatoire de Haute Provence in France. Both telescopes were specifically designed to do stellar spectroscopy and astrophotography, and the 1.52-m in La Silla involved no less than five instruments, including the B&C spectrograph. This instrument captured the spectrum of the Hale-Bopp comet as it passed by in 1995, one of the first recorded spectrums of a comet. After over 30 years of service, the 1.52-m at La Silla was decommissioned in 2002. Still sitting in its dome, it peers out over the vast Atacama Desert, and we get to marvel about all the things it has seen in the night sky. Credit: Zdeněk Bardon/ESO & Beowulf | |
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| Jase1Posted at 2023-05-12 20:14:33(80Wks ago) Report Permalink URL | ||
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| Fireball ‘100 times the size of the solar system’ thought to have been caused by gas being sucked into supermassive black hole  It started as an unremarkable flicker in the night sky. But closer observations revealed that astronomers had captured the largest cosmic explosion ever witnessed, an event thought to have been triggered by a giant cloud of gas being gobbled up by a supermassive black hole. The flare-up, traced to 8bn light years away, is more than 10 times brighter than any known supernova and has so far lasted more than three years, making it the most energetic explosion on record. “It went unnoticed for a year as it gradually got brighter,” said Dr Philip Wiseman, an astronomer at Southampton University who led the observations. It was only when follow-up observations revealed how distant it was that astronomers appreciated the event’s almost unimaginable scale. “We’ve estimated it’s a fireball 100 times the size of the solar system with a brightness about 2tn times the sun’s,” Wiseman said. “In three years, this event has released about 100 times as much energy as the sun will in its 10bn-year lifetime.” Scientists believe that the explosion, known as AT2021lwx, is the result of a vast cloud of gas, possibly thousands of times larger than our sun, plunging into the inescapable mouth of a supermassive black hole. The cloud of gas may have originated from the large dusty “doughnut” that typically surrounds black holes – although it is not clear what may have knocked it off course from its orbit and down the cosmic sinkhole. AT2021lwx is not the brightest phenomenon ever witnessed. A brighter gamma-ray burst, known as GRB 221009A, was spotted last year, but this event lasted only minutes. By contrast, the new event is still going strong, meaning the overall energy release is far greater. The explosion was first detected in 2020 by the Zwicky Transient Facility in California, which surveys the night sky for sudden increases in brightness that could signal cosmic events such as supernovae or passing asteroids and comets. The event initially did not stand out, but when follow-up observations allowed its distance to be calculated, astronomers realised they had captured an incredibly rare event. “When I told our team the numbers they were all just so shocked,” Wiseman said. “Once we understood how extremely bright it was, we had to come up with a way to explain it.” It was outside the plausible range for a supernova (exploding star) and so astronomers turned to the other common scenario that cause bright flashes in the night sky – a so-called tidal disruption event. These events typically involve a star straying too close to a black hole and being shredded, with part being swallowed and the rest being stretched out in a swirling disc. But simulations suggested a star up to 15 times the mass of the sun would have been required to account for AT2021lwx. “Encountering such a huge star is very rare, so we think a much larger cloud of gas is more likely,” Wiseman said. Supermassive blackholes are typically surrounded by a vast halo of gas and dust, and the authors speculate that some of this material may have been disrupted, possibly by a collision of galaxies, and sent inwards. As the material spiralled towards the black hole’s event horizon (its spherical outer boundary), it would have given off vast amounts of heat and light, illuminating a portion of the doughnut and heating it to 12-13,000C. Credit Hannah Devlin 00:01 BST Friday, 12 May 2023 | |
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| Jase1Posted at 2023-05-13 16:23:12(80Wks ago) Report Permalink URL | ||
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|  The arc of thin, distorted objects around the center of this image is a clear indication of gravitational lensing. (credit: Patrick Kelly, University of Minnesota) Anyone who has ever measured something twice, like the width of a doorway, and gotten two different answers knows how annoying it can be. Now imagine you're a physicist, and what you're measuring tells us something fundamental about the Universe. There are a number of examples like this—we can't seem to get measurements to agree on how long neutrons survive outside of atomic nuclei, for example. But few of these are more fundamental to the Universe's behavior as disagreements over what's called the Hubble Constant, a measure of how quickly the Universe is expanding. We've measured it using information in the cosmic microwave background and gotten one value. And we've measured it using the apparent distance to objects in the present-day Universe and gotten a value that differs by about 10 percent. As far as anyone can tell, there's nothing wrong with either measurement, and there's no obvious way to get them to agree. Now, researchers have managed to make a third, independent measure of the Universe's expansion by tracking the behavior of a gravitationally lensed supernova. When first discovered, the lens had created four images of the supernova. But sometime later, a fifth appeared, and that time delay is influenced by the Universe's expansion—and thus the Hubble constant. Inconsistent constant The Hubble constant is a measure of the Universe's expansion, as you can tell from its units, which are kilometers per second per Megaparsec. So, each second, every Megaparsec of the Universe expands by a certain number of kilometers. Another way to think of this is in terms of a relatively stationary object a Megaparsec away: each second, it gets a number of kilometers more distant. How many kilometers? That's the problem here. Measurements of the Cosmic Microwave Background using the Planck satellite produced a value of 67 km/s Mpc. Those done by tracking distant supernovae produce a value of 73 km/s Mpc. We're not sure why those measurements should differ, or whether there's a technical problem with one of them we've not yet identified. But it's considered a significant unsolved issue. The new work involves a third way to measure the distance that's independent of the other two. It relies on gravitational lensing, where the distortion in space-time caused by a massive object acts as a lens to magnify an object in the background. Since these aren't perfect optical-quality lenses, there are often some distortions and unevenness. This causes the light from the background object to take different paths to Earth, and thus a single object can appear in several different locations distributed around the lens. At cosmological scales, those paths can also require the light to travel very different distances to get to Earth. And, since light travels at a finite speed, it means we can look at a single object as it was at different times. Last year, for example, researchers identified a single Hubble Space Telescope image that captured a supernova as it was at three different times after its explosion. The new work focuses on a similar instance, a supernova first identified in 2014, and now called SN Refsdal, after the astronomer who first proposed using lensed explosions to perform measurements. When first detected, the distant SN Refsdal was lensed by a cluster of galaxies called MACS J1149.6+2223, which created four distinct images of it. But studies of the lens formed by MACS J1149.6+2223 quickly showed that it would create an additional image roughly a year later. Those predictions turned out to be correct. Images taken in late 2015 identified the fifth image of the event created by the gravitational lens. Measuring stick The time delays we observed measure the additional distance traveled by the light on its way to Earth. And those distances are large enough that they'll be influenced by the expansion of the Universe. So, measure things precisely enough, and we should have a value for the Universe's expansion—another route to the Hubble constant. This idea was what got the supernova named after Sjur Refsdal in the first place. The problem, however, is that we don't know the exact path taken by the light in this case. Most of the mass of the galaxy cluster is in the form of dark matter, so we can't image it directly. We can make models of where that mass is likely to be based on the location of visible matter. But we typically verify those models based on how well they reproduce the lensed images. But in this case, the data we're trying to understand are the lensed images. So you can't really use the images as both an input and output of the same analysis. To deal with this, the researchers treated the whole thing as an optimization problem. They took several models of the gravitational lens and tried them with a range of values for the Hubble constant and looked for which combinations of model plus constant gave the best match to the location of the lensed images and the appearance of the delayed fifth image. The best fits of their models all ended up slightly below the value of the Hubble constant derived from the Cosmic Microwave Background, with the difference being within the statistical error. Values closer to those derived from measurements of other supernovae were a considerably worse fit for the data. The researchers are careful to say that this doesn't mean we should rule out the higher value. The method is too new, and the uncertainties it produces with just a single supernova are too significant to view it as a last word. But it's still significant, in part because it provides an independent means of getting at the Hubble Constant, and in part because there is the prospect of identifying future examples of lens-delayed supernovae that can give us more data. Finally, it's interesting that the data was produced by a relatively mature Universe, one with stars and galaxies present. And yet it produced a value that's more consistent with that generated from the Cosmic Microwave Background, which was formed early in the Universe's history. So it at least suggests that the difference between the two other measures of the Hubble Constant isn't a product of something distinct to the early Universe. | |
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| Jase1Posted at 2023-05-13 16:34:12(80Wks ago) Report Permalink URL | ||
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|  Scientists think Saturn’s rings are just babies in cosmic terms Saturn’s spectacular rings are just 400 million years old – less than a tenth the age of the planet, according to new research. They are much younger than previously believed – solving a mystery that has puzzled astronomers for centuries. A US team came up with the answer by studying dust. They likened it to analysing a carpet in an unvacuumed room. Lead author Professor Sascha Kempf explained: ‘Think about the rings like the carpet in your house. ‘If you have a clean carpet laid out, you just have to wait. Dust will settle on your carpet. The same is true for the rings.’ It is the first time a definitive age has been put on Saturn’s iconic rings. Some experts have argued the stunning loops of icy particles formed along with the planet itself. Others suggested they were a recent phenomenon – perhaps the crushed up remains of a moon or a passing comet that was involved in a collision.  The University of Colorado Boulder team decided to resolve the dispute. They peg their age at ‘no more than 400 million years old’. Professor Kempf said: ‘That makes the rings much younger than Saturn itself, which is about 4.5billion years old. ‘In a way, we have closure on a question that started with James Clerk Maxwell.’ The famous Scottish physicist first showed they must consist of countless particles. The Maxwell Gap within Saturn’s C ring is named after him. Tiny grains of rocky material wash through Earth’s solar system on an almost constant basis. In some cases, this flux can leave behind a thin layer of dust on planetary bodies, including on the ice that makes up Saturn’s rings. Professor Kempf and her colleagues studied how rapidly this layer builds up – a bit like telling how old a house is by running your finger along its surfaces. They used an instrument called the Cosmic Dust Analyzer aboard Nasa’s Cassini spacecraft to analyse orbiting specks between 2004 and 2017. Over those 13 years, the researchers collected just 163 grains that had originated from beyond the planet’s close neighbourhood. They were enough to suggest the rings have been gathering dust for only a few hundred million years. In other words, they are a new phenomena, arising, and potentially even disappearing, in what amounts to a blink of an eye in cosmic terms.  Professor Kempf said: ‘We know approximately how old the rings are, but it doesn’t solve any of our other problems. We still don’t know how these rings formed in the first place.’ Scientists have been captivated by the seemingly-translucent rings for more than 400 years. In 1610, Italian astronomer Galileo Galilei first observed the features through a telescope, although he didn’t know what they were. His original drawings make the rings look a bit like the handles on a water jug. In the 1800s, Maxwell concluded the rings couldn’t be solid but were, instead, made up of many individual pieces. It is now known Saturn hosts seven rings comprised of countless chunks of ice, most no bigger than a boulder on Earth. Altogether, this ice weighs about half as much as Saturn’s moon Mimas and stretches nearly 175,000miles from the planet’s surface. For most of the 20th Century, it was assumed the rings likely formed at the same time as Saturn.  But they sparkle. Observations suggest they are made up of 98% pure water ice by volume, with only a tiny amount of rocky matter. Cassini first arrived at Saturn in 2004 and collected data until it was purposefully crashed into the planet’s atmosphere in 2017. The Cosmic Dust Analyser, which was shaped a bit like a bucket, scooped up small particles as they whizzed by. Engineers and scientists have designed and built a much more sophisticated version for Nasa’s upcoming Europa Clipper mission, scheduled to launch in 2024. The team estimated that this interplanetary grime would contribute far less than a gram of dust to each square foot of Saturn’s rings every year – a light sprinkle, but enough to add up over time. Previous studies had also suggested the rings could be young but didn’t include definitive measures of dust accumulation. And they might already be vanishing. In a previous study, Nasa scientists reported that the ice is slowly raining down onto the planet and could disappear entirely in another 100million years. That these ephemeral features existed at a time when Galileo and the Cassini spacecraft could observe them seems almost too good to be true. Professor Kempf said: ‘If the rings are short lived and dynamical, why are we seeing them now? It is too much luck.’ The study is published in the journal Science Advances. Credits Mark Waghorn Friday 12 May 2023 7:00 pm | |
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| BeowulfPosted at 2023-05-13 17:29:47(80Wks ago) Report Permalink URL | ||
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|  The NASA/ESA Hubble Space Telescope is famous for its jaw-dropping snapshots of the cosmos. At first glance this Picture of the Week appears to be quite the opposite, showing just a blur of jagged spikes, speckled noise, and weird, clashing colours — but once you know what you are looking at, images like this one are no less breathtaking. This shows a distant galaxy — visible as the smudge to the lower right — as it begins to align with and pass behind a star sitting nearer to us within the Milky Way. This is an event known as a transit. The star is called HD 107146, and it sits at the centre of the frame. Its light has been blocked in this image to make its immediate surroundings and the faint galaxy visible — the position of the star is marked with a green circle. The concentric orange circle surrounding HD 107146 is a circumstellar disc — a disc of debris orbiting the star. In the case of HD 107146 we see the disc face-on. As this star very much resembles our Sun, it is an interesting scientific target to study: its circumstellar disc could be analogous to the asteroids in our Solar System and the Kuiper belt. A detailed study of this system is possible because of the much more distant galaxy — nicknamed the “Vermin Galaxy” by some to reflect their annoyance at its presence — as the star passes in front of it. The unusual pairing was first observed in 2004 by Hubble’s Advanced Camera for Surveys, and again in 2011 by Hubble’s Space Telescope Imaging Spectrograph. The latter image is shown here, as the Vermin Galaxy began its transit behind HD 107146. The galaxy will not be fully obscured until around 2020, but interesting science can be done even while the galaxy is only partly obscured. Light from the galaxy will pass through the star’s debris discs before reaching our telescopes, allowing us to study the properties of the light and how it changes, and thus infer the characteristics of the disc itself. Credit: ESA/Hubble & NASA & Beowulf | |
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| Jase1Posted at 2023-05-14 19:40:50(80Wks ago) Report Permalink URL | ||
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| By Andy Tomaswick Sat May 13 06:42:24 GMT 2023  Lead Image: Image from the Solar Dynamics Observatory of a solar flare captured in 2014. Credit – NASA / SDO We’ve touched on the hazards of solar storms plenty of times in the past. We’ve also recently started reporting even more stories involving some sort of AI, especially in the last few months since it has come back to the forefront of many discussions around technologies. So it should come as no surprise that a team at NASA has been busily applying AI models to solar storm data to develop an early warning system that they think could give the planet about 30 minutes notice before a potentially devastating solar storm hits a particular area. That lead time is thanks to the fact that light (i.e., what radio signals are made out of) can travel faster than the solar material ejected out of the Sun in the event of these solar storms. In some events, such as one that impacted Quebec around 35 years ago, they can shut off power for hours. More extreme events, such as the Carrington event that happened more than 150 years ago, can cause massive destruction of electrical and communication infrastructure if they were to happen today. Scientists have long been aware of the problem and haven’t sat idly by. At this point in our species’ exploration of the solar system, plenty of satellites are looking at the Sun that can be used to identify these solar outbursts. Some of those satellites include ACE, Wind, IMP-8, and Geotail, which supplied data to the NASA team. But, as any AI researcher can tell you, in order to develop a predictive model, you have to tell it what it is meant to predict. Knowing simply that a solar storm is on its way is only one part of the battle – you also have to know what kind of impact it will have on the Earth when it hits there. So the researchers also collected data from surface-based stations that were also affected by some storms that the satellites detected. The scientists then set about training a deep learning model, which has recently become almost a household word. In this case, they named it DAGGER, and it has some pretty impressive specifications compared to existing predictive algorithms that have attempted to do the same thing. Most notable is its increase in speed. The researchers, led by Vishal Upendran from the Inter-University Center for Astronomy and Astrophysics in India, claim that the algorithm can predict the severity and direction of a solar storm event in under a second and that it is capable of making a prediction every minute. Previous attempts by earlier algorithms would take orders of magnitude longer – almost to the point where they would give hardly any warning time before a storm hit the Earth. Part of that struggle with timeliness was because it was computationally challenging to calculate where a storm might hit anywhere on the globe. That is another step forward for DAGGER, which can perform its quick prediction logic for the entire Earth’s surface area. Making such predictions locally is extremely important – at any point in time when a solar storm might hit the Earth, half of the globe will be protected by the planet’s entire bulk – in a state of what we commonly refer to as “night.” This combined speed of prediction with the ability to apply those predictions to an entire globe makes DAGGER a considerable step forward in predicting and accurately responding to potential hazards from solar storms. And it is launching on an open source platform just in time to collect plenty of data as the Sun ramps up to the peak of its 11-year solar cycle in 2025. That gives utility and communication companies a few years to integrate DAGGER into their threat assessment systems before the most severe weather comes. While there might not be any wailing sirens similar to tornado warning sirens, we have here in the Midwest of the US, at least the right people will be made aware of the danger faster than they would have been before. | |
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| Jase1Posted at 2023-05-15 14:02:21(80Wks ago) Report Permalink URL | ||
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|  The James Webb Space Telescope (JWST) continues to peer backwards through cosmic time, revealing the processes that created the universe as we see it today. Astronomers have used the James Webb Space Telescope to stare through the dusty clouds of a distant star-forming galaxy to investigate its structure in fine detail. They discovered that the galaxy is in the midst of a starburst, an explosive surge in star formation possibly caused by a collision with another galaxy. Located at a distance of around 12 billion light-years away, the galaxy GN20 is one of the earliest active star-forming galaxies studied in detail thus far by astronomers. It also happens to be one of the most luminous dusty star-forming galaxies ever studied. GN20 is located in a region of space called a galaxy overdensity or a protocluster. In these regions, galaxies will eventually group together to form a massive collection called a galactic cluster. The early galaxy, which was seen as it was when the 13.8 billion-year-old universe was just around 1.8 billion years old, is forming stars at a rate of around 1,860 times the mass of the sun each year. Clumpy molecular gas surrounds the galaxy expanding out to a diameter of around 46,000 light-years, and this star-forming matter is flattened into a giant rotating disk. Star-forming galaxies are surrounded by dense clouds of dust and gas that collapse in over-dense patches to form stars; these also make them difficult to investigate. This is because these clouds are adept at absorbing visible light, but infrared light has a much easier time slipping through this star-forming matter. That means the JWST, which was designed to see the universe in infrared wavelengths, is ideal for peering beyond these dusty veils to see deep into these galaxies. To study GN20 and unveil its properties, astronomers led by Spanish Astrobiology Center scientist Luis Colina used observations of this galaxy made by the JWST's Mid-Infrared Instrument (MIRI) between November 23 and 24, 2022.  The astronomers found that the early star-forming galaxy has a concentrated bright nucleus of densely clustered stars at its core surrounded by a diffuse envelope of gas. This inner structure of GN20 is birthing stars at a rate of about 500 times the mass of the sun each year and has been doing so for a period of around 100 million years. The observations also showed this nucleus is under 2,600 light-years in diameter, while its gaseous envelope has a diameter of around 23,000 light-years. The center of the gas is off-center in relation to GN20's dense nucleus of stars, implying that GN20 has recently undergone an encounter with another galaxy. This deformation in the gas envelope may have been the result of gravity tugging at it as the two galaxies passed each other, or it could be an artifact arising from a more permanent collision and merger between two galaxies. Interactions like this are often theorized to be the cause of intense periods of star formation in galaxies. The team behind this research concluded that GN20 will eventually become a massive galaxy resembling those found in the local universe around the Milky Way with its bout of intense star formation eventually coming to an end leaving it inactive or quiescent. | |
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| Jase1Posted at 2023-05-16 14:16:35(80Wks ago) Report Permalink URL | ||
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|  Webb telescope spots water in rare comet Astronomers used the James Webb Space Telescope to observe a rare comet in our solar system, making a long-awaited scientific breakthrough and stumbling across another mystery at the same time. For the first time, water was detected in a main belt comet, or a comet located in the main asteroid belt between the orbits of Mars and Jupiter. The discovery came after 15 years of attempts by astronomers using different observation methods. The space observatory detected water vapor around Comet Read, which suggests that water ice can be preserved in a warmer part of the solar system. A study detailing the findings was published Monday in the journal Nature. Comets typically exist in the Kuiper Belt and the Oort Cloud, icy regions beyond the orbit of Neptune that can preserve some of the frozen materials left over from the formation of the solar system. The comets venture on long, oval-shaped orbits around the sun that can take thousands of years and have streaming tails that develop as the frigid objects occasionally pass close to the sun. Their fuzzy appearance and tails of material differentiate comets from asteroids. But a rare subclass of comets called main belt comets are objects in the asteroid belt with circular orbits around the sun that periodically exhibit cometlike behavior, such as shedding material that creates a fuzzy appearance and a trailing tail. Rather than shedding icy material through sublimation, when a solid turns directly to a gas, the main belt comets only seemed to eject dust. Given their location in the warm inner solar system closer to the sun than typical comets, main belt comets weren't expected to retain much ice — until now. And the discovery could add more evidence to the theory of how water became a plentiful resource on Earth early in its history. Comets and water-rich asteroids may have collided with early Earth and delivered water to our planet. "Our water-soaked world, teeming with life and unique in the universe as far as we know, is something of a mystery — we're not sure how all this water got here," said study coauthor Stefanie Milam, Webb deputy project scientist for planetary science at NASA's Goddard Space Flight Center in Greenbelt, Maryland, in a statement. "Understanding the history of water distribution in the solar system will help us to understand other planetary systems, and if they could be on their way to hosting an Earth-like planet." Investigating rare comets Main belt comets were first codiscovered in 2006 by study coauthor Henry Hsieh, senior scientist at the Planetary Science Institute in Tucson, Arizona. Comet Read was one of the original comets used to create the subcategory. The precise data collected by Webb's Near-Infrared Spectrograph helped astronomers to determine the signature of water vapor around Comet Read shortly after its close approach to the sun.  The James Webb Space Telescope captured an image of Comet 238P/Read using its NIRCam instrument on September 8. NASA/ESA/CSA/M. Kelley/H. Hsieh/A. Pagan "In the past, we've seen objects in the main belt with all the characteristics of comets, but only with this precise spectral data from Webb can we say yes, it's definitely water ice that is creating that effect," said lead study author Michael Kelley, astronomer and principal research scientist at the University of Maryland in College Park, in a statement. "With Webb's observations of Comet Read, we can now demonstrate that water ice from the early solar system can be preserved in the asteroid belt." Along with the discovery came a new puzzle. Comet Read has no detectable carbon dioxide, which is an ingredient that makes up about 10% of the material vaporized by the sun in all other comets. It's possible that the warmer temperatures of the main asteroid belt cause Comet Read to lose its carbon dioxide over time, the researchers said. "Being in the asteroid belt for a long time could do it — carbon dioxide vaporizes more easily than water ice, and could percolate out over billions of years," Kelley said. Comet Read might have also formed in a warmer pocket of the solar system without carbon dioxide, Kelley said. The observation team is eager to study other main belt comets and compare them with Webb's data from Comet Read to see if the celestial objects also lack carbon dioxide and determine the next steps for unlocking the secrets of rare comets. "Now that Webb has confirmed there is water preserved as close as the asteroid belt, it would be fascinating to follow up on this discovery with a sample collection mission, and learn what else the main belt comets can tell us," Milam said. Credit Ashley Strickland, CNN 5:10 PM EDT May 15, 2023 | |
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| BeowulfPosted at 2023-05-16 17:49:15(80Wks ago) Report Permalink URL | ||
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|  Have you ever seen a sunset so red? Probably not, since the cause of this reddened twilight sky is something quite dramatic: a volcanic eruption. This Picture of the Week was captured at ESO’s Paranal Observatory in Chile; under the Milky Way, on the top of the dark silhouette of Cerro Paranal, ESO’s Very Large Telescope looks upwards to the sky. On 15 January 2022, the submarine volcano Hunga Tonga–Hunga Ha‘apai erupted in the southern Pacific Ocean. This eruption created shock waves that rippled through the atmosphere, reaching places far from the volcano itself. At ESO’s Paranal and La Silla observatories in Chile, more than 10 000 kilometres away, weather stations detected these atmospheric disturbances. The eruption also launched an ash plume 57 kilometres tall, releasing massive quantities of particles into the atmosphere, including water vapour and dust. Sunlight is scattered and reddened by these tiny dust particles, and this effect was detected in calibration images taken during twilight by several ESO telescopes. This Picture of the Week, taken 6 months after the eruption, shows that the effects of these particles were not transitory. At the time of writing, one year later, the sky has still not returned to its pre-eruption state. Credit: ESO/F. Selman & Beowulf | |
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| Jase1Posted at 2023-05-17 17:40:03(80Wks ago) Report Permalink URL | ||
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|  A colour-exaggerated view of Saturn backlit by the sun., NASA/JPL/Space Science Institute Saturn’s rings are one of the jewels of the solar system, but it seems that their time is short and their existence fleeting. A new study suggests the rings are between 400 million and 100 million years old – a fraction of the age of the solar system. This means we are just lucky to be living in an age when the giant planet has its magnificent rings. Research also reveals that they could be gone in another 100 million years. The rings were first observed in 1610 by the astronomer Galileo Galilei who, owing to the resolution limits of his telescope, initially described them as two smaller planets on each side of Saturn’s main orb, apparently in physical contact with it. In 1659, the Dutch astronomer Christiaan Huygens published Systema Saturnium, in which he became the first to describe them as a thin, flat ring system that was not touching the planet. He also showed how their appearance, as viewed from Earth, changes as the two planets orbit the Sun and why they seemingly disappear at certain times. This is due to their viewing geometry being such that we on Earth periodically see them edge-on. The rings are visible to anyone with a decent pair of binoculars or a modest back garden telescope. Cast white against the pale yellow orb of Saturn, the rings are composed almost entirely of billions of particles of water ice, which shine by scattering sunlight.  A page from the System Saturnium published in 1659. US Library of Congress Amid this icy material are deposits of darker, dusty stuff. In space science, “dust” usually refers to tiny grains of rocky, metallic, or carbon-rich material that is noticeably darker than ice. It is also collectively referred to as micrometeoroids. These grains permeate the solar system. Occasionally, you can see them entering the Earth’s atmosphere at night as shooting stars. The gravitational fields of the planets have the effect of magnifying or focusing this dusty, planetary “in-fall”. Over time, this in-fall adds mass to a planet and alters its chemical composition. Saturn is a massive gas giant planet with a radius of some 60,000km, about 9.5 times that of Earth, and a mass of about 95 times that of Earth. This means it has a very large “gravity well” (the gravitational field surrounding a body in space) that is very effective at funnelling the dusty grains towards Saturn.  A view of Saturn's northern hemisphere in 2016. NASA/JPL-Caltech/Space Science Institute Collision course The rings extend from some 2,000km above Saturn’s cloud tops to about 80,000km away, occupying a large area of space. When in-falling dust passes through, it can collide with icy particles in the rings. Over time, the dust gradually darkens the rings and adds to their mass. Cassini-Huygens was a robotic spacecraft launched in 1997. It reached Saturn in 2004 and entered orbit around the planet, where it stayed until the end of the mission in 2017. One of the instruments aboard was the Cosmic Dust Analyzer (CDA). Using data from the CDA, the authors in the new paper compared the current dust counts in space around Saturn with the estimated mass of dark dusty material in the rings. They found that the rings are no older than 400 million years and may be as young as 100 million years. These may seem like lengthy time scales, but they are less than one-tenth of the 4.5 billion-year age of the solar system. This also means that the rings did not form at the same time as Saturn or the other planets. They are, cosmologically speaking, a recent addition to the solar system. For over 90% of Saturn’s existence, they were not present. Death Star This leads to another mystery: how did the rings first form, given that all of the solar system’s major planets and moons formed much earlier? The total mass of the rings is estimated to be about half as much as one of Saturn’s smaller icy moons, many of which exhibit enormous impact features on their surfaces. One in particular, the little moon Mimas, which is nicknamed the Death Star, has a 130km-wide impact crater called Herschel on its surface.  Saturn's moon Mimas, showing Herschel crater. NASA/JPL/SSI This is by no means the largest crater in the solar system. However, Mimas is only about 400km across, so this impact would not have needed much more energy to obliterate the moon. Mimas is made of water-ice, just like the rings, so it’s possible that the rings were formed from just such a cataclysmic impact. Ring rain However they formed, the future of Saturn’s rings is in little doubt. The impact of the dust grains against the icy particles happens at very high velocities, leading to tiny fragments of ice and dust getting chipped away from their parent particles. Ultra-violet light from the Sun causes these fragments to become electrically charged via the photo-electric effect. Like the Earth, Saturn has a magnetic field, and once charged, these tiny icy fragments are released from the ring system and trapped by the planet’s magnetic field. In concert with the gravity of the giant planet, they are then funnelled down into Saturn’s atmosphere. This “ring rain” was first observed from afar by the Voyager 1 and Voyager 2 spacecraft during their brief Saturn flybys in the early 1980s. In a more recent paper from 2018 scientists used dust counts, again from the CDA, as Cassini flew between the rings and Saturn’s cloud tops, to work out how much ice and dust is lost from the rings over time. This study demonstrated that about one Olympic-sized swimming pool of mass from the rings is lost into Saturn’s atmosphere every half-hour. This flow rate was used to estimate that, given their current mass, the rings will probably be gone in as little as 100 million years. These beautiful rings have a turbulent history, and unless they are somehow replenished, they will be gobbled up by Saturn. Post Doctoral Research Fellow in Space Science, University of Birmingham | |
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| SoupPosted at 2023-05-18 03:00:19(80Wks ago) Report Permalink URL | ||
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| James Webb's 'too massive' galaxies may be even more massive by Niels Bohr Institute  This image of galaxy cluster SMACS 0723 and its surroundings was the first image released from the James Webb Space Telescope in July 2023. The five zoom-ins are each roughly 19,000 lightyears across, and show galaxies seen some 13 billion years back in time. Careful analysis of these galaxies reveals that if we cannot resolve a galaxy, we may severely underestimate the total mass of its stars. Credit: NASA, ESA, CSA, STScI / Giménez-Arteaga et al. (2023), Peter Laursen (Cosmic Dawn Center) The first results from the James Webb Space Telescope have hinted at galaxies so early and so massive that they are in tension with our understanding of the formation of structure in the universe. Various explanations have been proposed that may alleviate this tension. But now a new study from the Cosmic Dawn Center suggests an effect which has never before been studied at such early epochs, indicating that the galaxies may be even more massive. If you have been following the first results from the James Webb Space Telescope, you have probably heard about the paramount issue with the observations of the earliest galaxies: They are too big. From a few days after the release of the first images, and repeatedly through the coming months, new reports of ever-more distant galaxies appeared. Disturbingly, several of the galaxies seemed to be "too massive." From our currently accepted concordance model of the structure and evolution of the universe, the so-called ΛCDM model, they simply shouldn't have had the time to form so many stars. Although ΛCDM is not a holy indestructible grail, there are many reasons to wait claiming a paradigm shift: The measured epochs at which we see the galaxies could be underestimated. Their stellar masses could be overestimated. Or we could just have been lucky and somehow have discovered the most massive of the galaxies at that time. A closer look But now Clara Giménez Arteaga, Ph.D. student at the Cosmic Dawn Center, proposes an effect that could further increase the tension. In essence, a galaxy's stellar mass is estimated by measuring the amount of light emitted by the galaxy, and calculating how many stars are needed to emit this amount. The usual approach is to consider the combined light from the whole galaxy. However, taking a closer look at a sample of five galaxies, observed with James Webb, Giménez Arteaga found that if the galaxy is regarded not as one big blob of stars, but as an entity build up of multiple clumps, a different picture emerges. "We used the standard procedure to calculate stellar masses from the images that James Webb has taken, but on a pixel-by-pixel basis rather than looking at the whole galaxy," says Giménez Arteaga. "In principle, one might expect the results to be the same: Adding the light from all pixels and finding the total stellar mass, versus calculating the mass of each pixel and adding all individual stellar masses. But they're not." In fact the inferred stellar masses now turned out to be up to ten times larger. The figure below shows the five galaxies with their stellar masses determined by both ways. If the two different approaches agreed, all galaxies would lie along the slanted line named "The same." But they all lie above this line.  The five galaxies placed in a diagram that shows both the stellar mass inferred in the “usual” way (blue numbers) and Clara Giménez-Arteaga’s pixel-by-pixel method (red numbers). In all cases, the masses found using the pixel-by-pixel method are larger. Credit: Giménez-Arteaga et al. (2023), Peter Laursen (Cosmic Dawn Center) Outshined So what is the reason that the stellar masses turn out to be so much larger? Giménez Arteaga explains, "Stellar populations are a mixture of small and faint stars on one hand, and bright, massive stars on the other hand. If we just look at the combined light, the bright stars will tend to completely outshine the faint stars, leaving them unnoticed. Our analysis shows that bright, star-forming clumps may dominate the total light, but the bulk of the mass is found in smaller stars." Stellar mass is one of the main properties used to characterize a galaxy, and Giménez-Arteaga's result highlights the importance of being able to resolve the galaxies. But for the most distant and faint ones, this is not always possible. The effect has been studied before, but only at much later epochs in the history of the universe. The next step is therefore to look for signatures that does not require the high resolution, and which correlate with the "true" stellar mass. "Other studies at much later epochs have also found this discrepancy. If we can determine how common and severe the effect is at earlier epochs, and quantify it, we will be closer to inferring robust stellar masses of distant galaxies, which is one of the main current challenges of studying galaxies in the early universe," concludes Clara Giménez Arteaga. The study has just been published in The Astrophysical Journal. The ΛCDM model "ΛCDM"—pronounced "Lambda-CDM"—is the moniker given to the best model we have for describing the structure and evolution of our universe. The model is based upon one of the most well-tested theories in physics, the theory of general relativity, which describes how matter affects space, and how space affects matter. In this model, the universe is assumed to consist primarily of an unknown substance known as dark energy, denoted by the Greek letter Λ, and cold dark matter (CDM), where "cold" means that it does not move around too fast. ΛCDM has been extremely successful in describing and predicting numerous phenomena. But we still do not know what dark matter and energy is, and we know that general relativity, despite its success, is not a complete theory. We therefore do expect ΛCDM eventually to be expanded or replaced by a better theory. | |
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| BeowulfPosted at 2023-05-18 10:35:21(80Wks ago) Report Permalink URL | ||
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|  The richly textured spiral galaxy NGC 2082 is found about 60 million light-years away in the constellation of Dorado (the Swordfish), deep in the southern sky. As seen here in a very detailed image from the Advanced Camera for Surveys on the NASA/ESA Hubble Space Telescope, filaments of dark dust splay across NGC 2082’s luminous curved arms and dense central bulge of stars. Hubble’s sharp vision also reveals many of the individual bright blue stars dotting the galaxy’s rather ragged spiral arms as well as many much more distant galaxies in the background. This galaxy is faintly visible in backyard telescopes and was first recorded by Sir John Herschel during his visit to the Cape of Good Hope in South Africa in the 1830s. NGC 2082 was also the host of a bright supernova that was spotted by the great visual supernova discoverer Rev R. Evans back in 1992. This picture was created from images taken through blue and near-infrared filters (F435W and F814W) using the Wide Field Channel of the Advanced Camera for Surveys. The total exposure time was 19 minutes per filter and the field of view is about 2.2 x 1.6 arcminutes in size. Credit: ESA/Hubble and NASA & Beowulf | |
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| Jase1Posted at 2023-05-18 13:01:29(80Wks ago) Report Permalink URL | ||
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| The origins of a Type Ia supernova have been revealed for the first time using radio emissions. For the first time ever, astronomers have discovered the origin of a unique type of stellar explosion known as a Type Ia supernova using radio emissions. These specific kinds of supernova can be used to measure distances in the Universe, and also to probe the nature of dark energy. The Type Ia supernova, known as SN 2020eyj, was first detected on 7 March 2020, but its true origins were unknown, until now.  Type Ia supernovae explained Type Ia supernovae occur in binary star systems – where two stars orbit each other – in which one of the stars is a white dwarf. The white dwarf consumes material from its companion star until it reaches its critical mass, which triggers a stellar explosion known as a supernova. And because an explosion’s brightness depends on the star’s mass, Type Ia supernovae always have the same luminosity. By comparing a Type Ia supernova’s apparent brightness as seen from Earth with its actual brightness, it can be used to calculate distances in space. Investigating SN 2020eyj Supernova 2020eyj was first discovered by the Zwicky Transient Facility camera on Palomar mountain in California, USA. That study was led by Erik Kool, researcher at the University of Stockholm, in collaboration with research institutes across the world. For this latest discovery, astronomers using the e-MERLIN telescope network operated by Jodrell Bank at The University of Manchester were able to study SN2020eyj and conclude that its binary star system was composed of a white dwarf and a Sun-like star. Radio telescopes enable astronomers to detect and amplify radio waves originating in space, interpreting them to study the Universe. The team behind this discovery studied the supernova’s light curve and infrared emission, narrow helium emission lines and radio counterpart. The results have been published in the journal Nature.  Dr David Williams, e-MERLIN Operations Support Scientist at The University of Manchester, says: “Astronomers have been trying to detect radio emission from a Type Ia supernova for a few decades. “Using e-MERLIN, the observatory staff were able to react quickly when we first heard of the potential interesting nature of this source from the authors of this study. “The exquisite angular resolution of e-MERLIN combined with its high sensitivity enabled the radio emission to be pinpointed to the supernova, which is critical for establishing that the multi-wavelength emission was linked and attributed to the same source.”  Javier Moldón, who participated in the discovery, says: “This first radio detection of a Type Ia supernova is a milestone that has allowed us to demonstrate that the exploded white dwarf was accompanied by a normal, non-degenerate star before the explosion. “In addition, with these observations, we can estimate the mass and geometry of the material surrounding the supernova, which allows us to better understand what the system was like before the explosion. “Now that we have demonstrated that radio observations can provide direct and unique information to understand this type of supernova, a path is opened to study these systems with the new generation of radio instruments, such as the Square Kilometre Array Observatory in the future.” | |
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| SuperbikemikePosted at 2023-05-18 14:56:50(80Wks ago) Report Permalink URL | ||
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| You know i find it disturbing to be using a telescope to view these and still not just send out minions to the planets and see up close and on them yes it will take years upon years to get there,, not in my lifetime but if done now at least our great grandkids may have a better understanding of whats actually on a planet and closer views of galaxies by being in them ... they havent even sent one into a black hole yet .  find habitable planets like the keplers send em off to them and land on them. thats it cam will send back a stream go from there.. not actually habitable next .. Last edited by Superbikemike on 2023-05-18 14:59:00 | |
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