Jase1        Posted at 2023-11-06 19:22:48(54Wks ago) Report Permalink URL | ||
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|  While looking at compiled data from NASA’s now-retired Kepler space telescope, astronomers have discovered the existence of a seven-planet system of sweltering planets larger than Earth but smaller than Neptune that scientists are calling Kepler-385. The discovery marks one of only a few planetary systems we have discovered that has more than six verified planets or planetary candidates. The discovery of Kepler-385 is exciting because it falls into a very small niche within the systems that we have discovered so far. And, because NASA’s now-retired Kepler space telescope discovered it, it proves that even older data has more information to reveal if we look back at it.  An illustration showing the orbits of Kepler-385’s seven planets. Image source: NASA/Daniel Rutter The newly discovered Kepler-385 includes a sun-like star at the center of it that is 10 percent larger and five percent hotter than our own solar system’s star. Both inner planets are larger than Earth, and scientists estimate they are both rocky and might even have thin atmospheres, which are estimated to be twice the size of Earth’s. The two inner planets are also expected to be enshrouded in thick atmospheres, NASA says. The data’s ability to describe the properties of the planets found in Kepler-385 is a testimony to the quality of the most recent catalog of exoplanets that Kepler discovered. The discovery of this system was only made possible thanks to the accurate information Kepler’s final catalogs produced. The discovery of Kepler-385 has also revealed that planets tend to have more circular orbits – similar to our own solar system – when there are more than two planets orbiting a star. While Kepler’s primary observations ended in 2013, NASA continued to peer into the universe with an extended mission, known as K2, which came to an end in 2018. Now, the data Kepler collected continues to reveal more information about our universe, including the existence of this rare planetary system. It not only gives us a better view of how many worlds exist beyond our little slice of the cosmos, but it also paints a more detailed picture of what those planets and their planetary systems might look like, which is exceptionally exciting. NASA also created a data sonification of the planetary system, which we’ve embedded above. It’s actually quite soothing to listen to, especially after hearing what a black hole sounds like. | |
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| Jase1Posted at 2023-11-07 16:56:08(54Wks ago) Report Permalink URL | ||
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| The animation in this Picture of the Week shows us the nearby galaxy NGC3456 in thousands of different colours or wavelengths of light, captured with ESO’s Very Large Telescope (VLT) at Paranal Observatory. Thanks to observations of more than 100 galaxies, including this one, astronomers are discovering there are properties of massive stars that could influence whether or not they end their lives in a spectacular supernova explosion. Core collapse supernovae are the extremely energetic deaths of massive stars, those with eight times or more mass than the Sun. Aside from their sheer size, the exact properties — such as chemical makeup — of the stars that die as supernovae are poorly understood because we rarely get to see them before they explode. But, we can study the explosion sites. A new study led by former ESO student Thallis Pessi at the Universidad Diego Portales (Chile) has done precisely that. The team analysed galaxies where supernovae have occurred, comparing the explosion sites themselves to all other regions within those galaxies. They found that the proportion of elements heavier than hydrogen or helium influences whether a supernova will happen: massive stars born out of gas with a lower abundance of these elements are more likely to explode as supernovae. The team used data from the Multi Unit Spectroscopic Explorer (MUSE) instrument at the VLT. MUSE breaks the light coming from every location within its field of view into a rainbow or spectrum, allowing the team to map the chemical composition of these galaxies. | |
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| BeowulfPosted at 2023-11-07 17:47:51(54Wks ago) Report Permalink URL | ||
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|  This image features the spiral galaxy NGC 941, which lies about 55 million light-years from Earth. The data used for this image were collected by Hubble’s Advanced Camera for Surveys (ACS). The beautiful NGC 941 is undoubtedly the main attraction in this image; however, this hazy-looking galaxy was not the motivation for the data being collected. That distinction belongs to an astronomical event that took place in the galaxy years before: the supernova SN 2005ad. The location of this faded supernova was observed as part of a study of multiple hydrogen-rich supernovae, also known as type II supernovae, in order to better understand the environments in which certain types of supernovae take place. Whilst the study was conducted by professional astronomers, SN 2005ad itself owes its discovery to a distinguished amateur astronomer named Kōichi Itagaki, who has discovered over 170 supernovae.  This might raise the question of how an amateur astronomer could spot something like a supernova event before professional astronomers — who have access to telescopes such as Hubble. The answer is in part that the detection of supernovae is a mixture of skill, facilities and luck. Most astronomical events happen over time spans that dwarf human lifetimes, but supernova explosions are extraordinarily fast, appearing very suddenly and then brightening and dimming over a period of days or weeks. Another aspect is that professional astronomers often do not spend that much time actually observing. There is a great deal of competition for time on telescopes such as Hubble, and then data from a few hours of observations might take weeks, months, or sometimes even years to process and analyse to their full potential. Amateur astronomers can spend much more time actually observing the skies, and sometimes have extremely impressive systems of telescopes, computers and software that they can put to use. So many supernovae are spotted by skilful amateurs such as Itagaki that there is actually an online system set up for reporting them (the Transient Name Server). This is a big help to professional astronomers, because with supernova events time is truly of the essence. After the discovery of SN 2005ab was reported, professional astronomers were able to follow up with spectroscopic studies and confirm it as a type II supernova, which eventually led to its location being included in this study with Hubble. Such a study wouldn’t be possible without a rich library of previous supernovae, built with the keen eyes of amateur astronomers. [Image Description: A spiral galaxy, seen face-on from Earth. The spiral arms of the galaxy are bright but not well defined, merging into a swirling disc with a faint halo of dimmer gas around it. The core glows brightly in a lighter colour and has a bit of faint dust crossing it. Two redder, visually smaller galaxies and a bright star are prominent around the galaxy, with more tiny objects in the background. Credit: ESA/Hubble & NASA, C. Kilpatrick & Beowulf  | |
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| SoupPosted at 2023-11-07 23:28:42(54Wks ago) Report Permalink URL | ||
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| This is a first: An exoplanet in a polar circumbinary disk surrounding two stars by Evan Gough, Universe Today  This illustration shows a binary star surrounded by a thick disc of material in a polar orbit. Credit: University of Warwick/Mark Garlick We live in an age of exoplanet discovery. One thing we've learned is not to be surprised by the kinds of exoplanets we keep discovering. We've discovered planets where it might rain glass or even iron, planets that are the rocky core remnants of gas giants stripped of their atmospheres, and drifting rogue planets untethered to any star. Now, astronomers have uncovered evidence of an exoplanet in a circumbinary disk around a binary star. The remarkable thing about this discovery is that the disk is in a polar configuration. That means the exoplanet moves around its binary star in a circumpolar orbit, and this is the first one scientists have found. AC Herculis (AC Her) is a binary star about 4,200 light-years away. The primary star is well-studied, while its partner is invisible. It has a polar circumbinary disk, which is unusual but not unheard of. In a new paper, a team of researchers presents evidence for the polar circumbinary exoplanet. The paper is "AC Her: Evidence of the first polar circumbinary planet." It is published on the pre-print server arXiv. The lead author is Rebecca Martin from the Nevada Center for Astrophysics at the University of Nevada, Las Vegas. "We examine the geometry of the post-asymptotic giant branch (AGB) star binary AC Her and its circumbinary disk. We show that the observations describe a binary orbit that is perpendicular to the disk," the authors write. The disk is close to a stable polar alignment, the authors explain, and the disk has a large inner radius. "The most likely explanation for the very large inner radius of the dust is a planet within the circumbinary disk." The circumbinary disk has the telltale gap that signals the presence of a planet. There's some uncertainty around the conclusion, and some of it stems from the size of the disk and the cavity the stars reside in in the center. In a circumpolar disk, there are different forces with different strengths at work that shape the stellar cavity. "The cavity size of a circumbinary gas disk depends upon the binary separation, the binary eccentricity and the inclination of the disk relative to the binary orbit," the researchers explain. In a circumpolar arrangement, the cavity in the middle of the system where the stars reside should be small. "The size of the binary cavity is, therefore, an important diagnostic for the inclination of the disk relative to the binary orbit," they write. A disk in a polar orientation could extend down to 1.6 AU before the stellar cavity begins. That's a large dust cavity, and its size supports the existence of an exoplanet.  These 3D visualizations show two different views of the AC Her binary system with a polar circumbinary disk. There’s a gap between the outer disk (brown) and the inner disk (red) that signals the presence of an exoplanet. If confirmed, it’s the first polar circumbinary planet astronomers have found. Credit: Martin et al. 2023 "The polar configuration of the disk in AC Her does not help to explain the large dust cavity since a polar-aligned disk has a smaller cavity size than a coplanar disk," Martin and her colleagues explain. "The best explanation remains the presence of a planet in the disk. Therefore, this is the first evidence of a polar circumbinary planet." Planet formation in a disk is the same whether the disk is coplanar or circumpolar. But there's an additional factor in the AC Her system. The primary star is a post-AGB star, meaning it has already left the main sequence and passed through its red giant phase. During that phase, a star expands voluminously, tearing nearby planets to shreds and spelling their doom. So this planet could be a second-generation exoplanet, re-formed from the debris from the destroyed first-generation planets. The circumbinary disk isn't exactly polar. A polar disk is inclined by 90° to the binary orbital plane, but this one is only off by 9%. "This is the first observed polar circumbinary disk around a post-AGB star," the authors write. The inner edge of the dust disk is further out than it should be, and this is another indication of an exoplanet. It's important to note that this is not a main sequence star and that astronomers have never seen a polar circumbinary planet around non-main sequence stars. "Therefore, this is the first observational evidence of a polar circumbinary planet," the authors point out. This planet is in the circumbinary disk, not in either of the circumstellar disks. The circumbinary disk actually feeds material into the circumstellar disks inside the stellar cavity, which can become fuel for more planet formation. But when a polar circumbinary disk feeds material into polar circumstellar disks, the arrangement may be unstable. Eventually, the polar circumstellar disk could become co-planar. The AC Her system isn't the first binary star with a polar disk. The first one was announced in 2019 around the star HD 98800. (HD 98800 is actually a quadruple star containing a pair of binary stars.) But as the first polar circumbinary disk to host a probable exoplanet, this unusual system begs to be studied more thoroughly. There's a lot we don't know about the planet, but that's not surprising. Even detecting one of these planets is extremely difficult. The best evidence we have for it lies in the characteristics of the disk itself. But in this study, the team only identified the likely presence of a planet. We know nothing about its mass, radius, or anything else. What type of planet is it? Does its formation in a polar circumbinar | |
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| panosolPosted at 2023-11-08 19:59:00(54Wks ago) Report Permalink URL | ||
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|  Aluminum rockets and steel skyscrapers; slick high-speed shuttles and glassy facades: that’s how “the future” has been imagined for decades. But that’s not what Koji Murata imagines. A researcher at Kyoto University in Japan, Murata has been exploring how biological materials could be used in space. Murata wondered if he “could build a wooden house on the moon or Mars,” and decided to test the theory — by creating a wooden satellite. Recent research from the National Oceanic and Atmospheric Administration (NOAA) found that 10% of atmospheric aerosol in the stratosphere contained metallic particles from spacecraft, including satellites. The long-term impact of these metal fragments is unknown, but scientists are concerned it could damage Earth’s fragile ozone layer. Wooden satellites would be better for the planet while still providing the same functionality as their metal counterparts, says Murata. “At the end of their life, satellites re-enter the atmosphere. The difference is, the wood in the LingoSat will burn up and eventually become a gas, whereas metals become fine particles instead,” says Murata. It’s not just a pipedream: Murata and his team have been working on the project for four years and sent wood samples to space in 2021 to test the material’s resilience to space conditions. Now, they are working with Japan’s space agency (JAXA) and NASA to send the prototype satellite, called LingoSat, into orbit early next year. Magnolia, cherry and birch For Murata, who is head of the space-wood project at Kyoto University, wood is an obvious choice for space structures. “When you use wood on Earth, you have the problems of burning, rotting, and deformation, but in space, you don’t have those problems: there is no oxygen in space, so it doesn’t burn, and no living creatures live in them, so they don’t rot,” he says.  Engineers at Kyoto University are building a wooden satellite that will be launched into space in a joint mission with JAXA and NASA. The strength per weight of wood is the same as aluminum which also makes it a compelling choice for space construction, Murata adds — and the team’s tests conducted at the International Space Station found that wood is remarkably resilient in outer space. For the satellite, Murata tested three wood types: Erman’s birch — which is commonly found in East Asia — Japanese cherry and magnolia obovata — a species native to Japan. While cypress and cedar would be more common wood types for construction, the team “chose materials that could withstand as much detailed work as possible,” because of the small size of the satellites, says Murata. Ultimately, the magnolia wood won, as its cells are small and uniform in size, which makes the wood easier to work with and less likely to split or break, he says. Sustainable satellites Humans have been putting satellites into orbit since the 1950s, with up to 100 spacecraft launched every year until 2010. But over the past decade, commercial launches have become more accessible and this number has increased dramatically, surpassing 1,400 new satellites in 2021. With the number of rockets sent to space likely to increase, the NOAA research projected that in the coming decades, as much as half of atmospheric aerosol in the stratosphere could contain metallic particles from spacecraft. Other organizations are also looking to use wood in space. Finnish startup Arctic Astronautics designed the WISA Woodsat, a wooden satellite that was supposed to be launched into space in 2021. However, company founder Jari Mäkinen says the launch has been held up by bureaucratic hurdles. “The satellite is ready, waiting in pieces to be put together again when the time comes,” Mäkinen told CNN in an email, adding that once the company receives its space operations license, the satellite will be launched with private rocket rideshare service RocketLab.  The satellite is made from magnolia wood, which was tested at the International Space Station with two other varieties. At Khalifa University in the United Arab Emirates, aerospace engineer Yarjan Abdul Samad is looking at graphene as a potential material for space objects. Samad is exploring “nano-wood” — a low-density wood combined with graphene to improve its strength. Samad agrees with Murata that as a renewable and low-density material, wood has the potential to not just build satellites, but future space structures. “There are many research (projects) going on for space agriculture,” says Samad. “If we have wood grown in space, it could be utilized for manufacturing in space.” However, there are still a lot of unknowns about wood in space structures, says Tatsuhito Fujita, an engineer at JAXA who has been involved in reviewing the LingoSat project. “The use of natural resources for space hardware (makes sense) from a sustainable development goals perspective, but since wood has never been used in satellites, we cannot tell what kind of benefit we can obtain at this moment,” says Fujita. For JAXA and the J-Cube Program, the initiative launching the satellite, the priority is safety – and the LingoSat passed its preliminary evaluation with no critical concerns, says Fujita. “JAXA also hopes for lighter, stronger structural materials that are less likely to generate debris, and is conducting research to achieve this goal.” To infinity  The researchers will monitor the satellite for at least six months as it orbits the Earth, as shown in this render. Credit: Kyoto University “There is not much reduction in strength from minus 150 to 150 degrees Celsius (-238 to 302 degrees Fahrenheit), we confirmed that in our experiments,” says Murata. “But a satellite goes round the Earth and has these huge temperature differences in 90 minutes. We don’t know to what extent the satellite can withstand this intense, repeated cycle of temperature difference, so this has to be investigated.” The team will also monitor its reactions to radio waves and magnetic fields, and how the wooden shell protects the satellite’s semiconductor and chip. In theory, wood should be a cheaper material to manufacture from, although as a novel technology, Murata says they are still working out the costs. So far, few materials have been used for space missions and objects, says Murata. He hopes that his research and the LingoSat can show the possibilities of other, lower-impact materials. “It is a renewable, environmentally friendly, and people-friendly material,” says Murata. “I think wood could be used in space development, particularly as an interior material and for radiation shielding material, for small satellites and manned space vehicles.” Original post on CNN | |
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| SoupPosted at 2023-11-09 00:43:03(54Wks ago) Report Permalink URL | ||
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| Enceladus has all the raw materials for life, researchers say by Evan Gough, Universe Today  Saturn's moon Enceladus isn't just bright and beautiful. It has an ocean under all that ice that has chemicals necessary for life. Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team Saturn's ocean moon, Enceladus, is attracting increasing attention in the search for life in our solar system. Most of what we know about Enceladus and its ice-covered ocean comes from the Cassini mission. Cassini ended its exploration of the Saturn system in 2017, but scientists are still working through its data. New research based on Cassini data strengthens the idea that Enceladus has the chemicals necessary for life. During its mission, Cassini discovered geyser-like plumes of water erupting through Enceladus' icy shell. In 2008, Cassini performed a close-proximity flyby and analyzed the plumes with its Cosmic Dust Analyzer (CDA). The CDA showed that the water in the plumes contained a surprising mix of volatiles, including carbon dioxide, water vapor, and carbon monoxide. It also found trace amounts of molecular nitrogen, simple hydrocarbons, and complex organic chemicals. But Cassini's data is still being analyzed, even six years after it completed its mission and was sent to its destruction in Saturn's atmosphere. A new paper posted to bioRxiv titled "Observations of Elemental Composition of Enceladus Consistent with Generalized Models of Theoretical Ecosystems" presents some new findings. The lead author is Daniel Muratore, a post-doc at the Santa Fe Institute. The work centers on the discovery of ammonia and inorganic phosphorous in Enceladus' ocean. The researchers used ecological and metabolic theory and modeling to understand how these chemicals could make Enceladus amenable to life. "Apart from speculating about threshold concentrations of bioactive compounds to support ecosystems, metabolic and ecological theory can provide a powerful interpretative lens to assess whether extraterrestrial environments are compatible with living ecosystems," the authors explain. A critical component of ecological theory is the Redfield ratio. It's named after the American oceanographer Alfred Redfield. In 1934, Redfield published results showing that the ratio of carbon to nitrogen to phosphorous (C:N:P) was remarkably consistent across ocean biomass at 106:16:1. Other researchers found that the ratio shifted slightly depending on the area and the phytoplankton species present. More recent work refined the ratio to 166:22:1. The exact numbers aren't necessarily the critical point. Redfield's conclusion is the vital part. The Redfield ratio shows a remarkable unity between the chemistry of living things in the deep ocean and the ocean itself. He proposed that there's an equilibrium between ocean water and plankton nutrients that's based on biotic feedback. He described a chemical framework for nutrients and simple life.  The plumes of Enceladus have phosphate-rich ice grains entrained. Credit: NASA "Whatever its explanation, the correspondence between the quantities of biologically available nitrogen and phosphorus in the sea and the proportions in which they are utilized by the plankton is a phenomenon of the greatest interest," Redfield said in the conclusion of his paper. So, how does the discovery of ammonia and phosphorous in Enceladus' ocean relate to the Redfield ratio and Enceladus' biological potential? The Redfield ratio is widespread all across the Tree of Life on Earth. "Because of this seeming ubiquity, the Redfield ratio has been considered a target signature for astrobiological life detection, especially on ocean worlds such as Europa and Enceladus," the authors of the new paper write. When it comes to life, all we have to go on is Earth. So it's sensible to use foundational aspects of life's chemistry here on Earth as a lens through which to examine other potential life-supporting worlds. Analysis of Cassini's data from Enceladus' plumes shows a high level of inorganic phosphate in the ocean. Other geochemical simulations based on Cassini's findings indicate the same. "These reports of phosphorus follow on the tails of previous work identifying numerous elemental constituents of terrestrial life (C, N, H, O) from the Enceladus plume," the authors explain. Even more analysis suggests that the ocean contains many of the chemicals common in living organisms, like amino acid precursors, ammonium, and hydrocarbons. So Enceladus' ocean has a rich chemistry, and many chemicals reflect life's chemical makeup. In particular, there's an emerging hypothesis that Enceladus could support methanogenesis. Earth's Archaea perform methanogenesis across a wide swath of different environmental conditions on Earth and have done so for over three billion years, proving their survivability. Biochemical modeling suggests that Earth's methanogens are compatible with Enceladus' ocean. The researchers developed a new, more detailed model for methanogens on Enceladus to see if they could survive and thrive there. Their model leaned heavily on the Redfield ratio. They found that though phosphorous is present in high levels in the moon's ocean, the overall ratio "may be limiting to Earth-like cells."  This figure illustrates a cross-section of Enceladus, summarizing the processes SwRI scientists modelled in the moon in a 2020 study. Oxidants produced in the surface ice when water molecules are broken apart by radiation can combine with reductants produced by hydrothermal activity and other water-rock reactions, creating an energy source for potential life in the ocean. Credit: SwRI "High standing stocks of these nutrients could be consistent with incomplete drawdown due to a small or metabolically slow biosphere, a biosphere with a recent origin of life," or other reasons that could cause an imbalance. So where does that leave the prospects for life on Enceladus? We're only at the beginning of biosignature science. We can identify individual chemicals, but from this great distance away, we can't accurately measure Enceladus' overall chemistry. Newer biosignature research, including this paper, aims to identify how biological processes reorganize chemical elements in telltale ways. By looking at entire ecosystems, as Redfield did, scientists may discover new biosignatures that are less ambiguous. If we can do that, we may discover that non-Earthly lifeforms reorganize chemicals in entirely different ways. This research is part of a new effort to detect more than individual chemical biosignatures, some of which can be false positives. Methane, for example, can be a biosignature but can also be produced abiotically. There are others, like the recently discovered phosphine on Venus. Understanding ecosystems as a whole is the next step. There's a bewildering number of factors to consider. Cell size, nutrient availability, radiation, salinity, temperature. On and on. But to understand the overall chemical environment at Enceladus, Europa, or anywhere else, we need more detailed data. Luckily, instrument science keeps improving, and upcoming missions to Europa will start to paint a fuller picture. According to the authors, the next step requires more fulsome data and a more generalized approach.  We’re improving at identifying individual chemicals on other worlds, and the JWST is leading the way. But we need a better understanding of overall chemical environments to advance the search for life. A transmission spectrum of the hot gas giant exoplanet WASP-39 b, captured by Webb’s Near-Infrared Spectrograph (NIRSpec) on July 10, 2022, reveals the first definitive evidence for carbon dioxide in the atmosphere of a planet outside the Solar System. Credit: NASA, ESA, CSA, and L. Hustak (STScI). Science: The JWST Transiting Exoplanet Community Early Release Science Team "We suggest two priorities for further astrobiological research to better understand the implications of these conclusions," they write. "First, we echo previous calls in the astrobiology literature to explore more generalized notions of metabolism and physiology." They also suggest that looking for direct parallels to terrestrial life in the form of biochemistry may not be the best strategy for looking for life on Enceladus. "Second, we recommend broadening the scope of Earth analog environments to include those with extreme resource supply ratios mirroring that suggested for Enceladus," they explain. Our understanding of habitability grows incrementally, as this study clearly shows. There'll likely be no revelatory moments where we suddenly understand it. Nature has created a vast variety of worlds, each with its own chemistry. While using tools like the Redfield ratio as a lens is one way of looking at these worlds in all their unique glory, we can't get tunnel vision. While most of what our imaginations dream up about life on other worlds is fanciful and unlikely, life could've found another way on Enceladus. There could be different ways that life exists in and reorganizes chemical environments. Last edited by Soup on 2023-11-09 03:37:03 | |
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| 19tommy59Posted at 2023-11-09 02:29:04(54Wks ago) Report Permalink URL | ||
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| Hey buddy truly fascinating stuff I cant get enough of this type of content thanks for the for uploading this as well as all your others keep it up please. Tommy | |
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| SoupPosted at 2023-11-09 03:38:42(54Wks ago) Report Permalink URL | ||
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| Surely will my old friend, along with the other members who also add to the topic  | |
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| Jase1Posted at 2023-11-09 17:15:13(54Wks ago) Report Permalink URL | ||
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|  Stargazers rejoice – we’re going to get a spectacular view of Uranus on Monday as it lines up perfectly with Earth. While the mysterious ice giant should be visible to the naked eye on a clear night, a basic pair of binoculars or telescope will enhance the view. But why is Uranus so massive right now? The answer is a phenomenon known as opposition. Due to the fact that Earth orbits the Sun much quicker than the planets further out to space, almost every year there is a point at which it flies directly between the Sun and a neighbouring planet. Mars is the exception – because it is so much closer to Earth, this meeting only happens once every 27 months.  However, for Jupiter, Saturn, Uranus and Neptune, Earth ‘catches up’ with them on its journey around the Sun. This is also the point at which the two planets are closest to each other, setting up some fantastic views – it looks extra bright because the Sun’s light is reflected straight back towards us. Eagle-eyed stargazers may have noticed Jupiter is particularly bright in the sky right now – it hit opposition on November 3. On this day, Jupiter was around 367 million miles from Earth. At its furthest, the gas giant is 601 million miles away. Next week, when Uranus looms into opposition, it will be around 1.6 billion miles from Earth. That’s still pretty far, but lucky Uranus is quite big – it’s about four times as wide as our planet, which will help those hoping to catch a glimpse of it. However, it’s not a ‘blink-and-you’ll-miss-it’ event says the Royal Observatory’s Dr Greg Brown, with the Uranus looking brighter than normal in the weeks before and after opposition. ‘To see it for yourself, you could try spotting it with your unaided eyes,’ he says. ‘But, given that it is barely within the ability of the eye to see, you would need excellent vision and very dark skies, free of light pollution, to have a decent chance of success. ‘A pair of binoculars or a small telescope will help considerably, making it visible even in bright cities if you are lucky. ‘For those in the UK it will be rising in the east around sunset, though it will be very tough to spot until twilight has ended. It will be at its highest at midnight, due south around 50 degrees above the horizon below the constellation of Aries. ‘If you are struggling to find it, look for two easy to spot sights: the almost unmissable bright point of light that is the planet Jupiter and the bright cluster of stars known as the Pleiades or the Seven Sisters – Uranus will be almost exactly halfway between the two.’  Uranus can be found in the sky between the Pleiades star cluster and Jupiter (Picture: Stellarium) There are many weird and wonderful things about Uranus. It is the only planet that rotates at a right angle to its orbit – imagine pointing the North Pole at the Sun and you get the idea. This means the dark side of the planet is plunged into a 21-year-long winter as Uranus makes its long journey around the Sun. This also means its two sets of dazzling rings are vertical, rather than horizontal as seen on Saturn.  Uranus and six of its brightest moons (Picture: Nasa, ESA, CSA, STScI) Uranus also spins in the opposite direction to all the other planets except Venus. And although known as an ice giant, the inside of Uranus is actually very hot. Almost all of the planet is made up of a hot dense fluid of ‘icy’ materials including water and methane which swirl around a small rocky core – here the interior reaches almost 5,000C. On the surface however life is very cold given the planet is so far from the Sun. It takes 84 Earth years for the planet to complete one orbit – yet one of its sideways days only lasts 17 hours and 14 minutes, so it is spinning much faster than us. | |
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| BeowulfPosted at 2023-11-09 17:49:44(54Wks ago) Report Permalink URL | ||
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|  The irregular galaxy Arp 263 lurks in the background of this image from the NASA/ESA Hubble Space Telescope, but the view is dominated by a stellar photobomber; the bright star BD+17 2217. Arp 263 — also known as NGC 3239 — is a patchy, irregular galaxy studded with regions of recent star formation, and astronomers believe that its ragged appearance is due to its having formed from the merger of two galaxies. It lies around 25 million light-years away in the constellation Leo. Two different Hubble investigations into Arp 263, using two of Hubble’s third-generation instruments, contributed data to this image. The first investigation was part of an effort to observe the sites of recent supernovae, such as the supernova SN 2012A that was detected just over a decade ago in Arp 263. Astronomers used Hubble’s powerful Wide Field Camera 3 to search for lingering remnants of the colossal stellar explosion. The second investigation is part of a campaign using Hubble’s Advanced Camera for Surveys to image all the previously unobserved peculiar galaxies in the Arp catalogue, including Arp 263, in order to find promising subjects for further study using the NASA/ESA/CSA James Webb Space Telescope. The interloping foreground star, BD+17 2217, is adorned with two sets of criss-crossing diffraction spikes. The interaction of light with Hubble’s internal structure means that concentrated bright objects such as stars are surrounded by four prominent spikes. Since this image of BD+17 2217 was created using two sets of Hubble data, the spikes from both images surround this stellar photobomber. The spikes are at different angles because Hubble was at different orientations when it collected the two datasets. [Image Description: An irregular galaxy that appears like a triangle-shaped patch of tiny stars. It is densest in the centre and along one edge, growing faint out to the opposite corner. Several bright pink patches mark areas of star formation, and the galaxy’s brightest stars are around these. A large, bright star, with two sets of long spikes, stands between the viewer and the galaxy. Credit: ESA/Hubble & NASA, J. Dalcanton, A. Filippenko & Beowulf | |
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| BeowulfPosted at 2023-11-13 17:48:04(53Wks ago) Report Permalink URL | ||
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|  This luminous tangle of stars and dust is the barred spiral galaxy NGC 1385, that lies about 30 million light-years from Earth. The same galaxy was the subject of another Hubble Picture of the Week, but the two images are notably different. This more recent image has far more pinkish-red and umber shades, whereas the former image was dominated by cool blues. This chromatic variation is not just a creative choice, but also a technical one, made in order to represent the different number and type of filters used to collect the data that were used to make the respective images. It is understandable to be a bit confused as to how the same galaxy, imaged twice by the same telescope, could be represented so differently in two different images. The reason is that — like all powerful telescopes used by professional astronomers for scientific research — Hubble is equipped with a range of filters. These highly specialised components have little similarity to filters used on social media: those software-powered filters are added after the image has been taken, and cause information to be lost from the image as certain colours are exaggerated or reduced for aesthetic effect. In contrast, telescope filters are pieces of physical hardware that only allow very specific wavelengths of light to enter the telescope as the data are being collected. This does cause light to be lost, but means that astronomers can probe extremely specific parts of the electromagnetic spectrum. This is very useful for a number of reasons; for example, physical processes within certain elements emit light at very specific wavelengths, and filters can be optimised to these wavelengths. Take a look at this week's image and the earlier image of NGC 1385. What are the differences? Can you see the extra detail (due to extra filters being used) in this week’s image? [Image Description: A spiral galaxy. It has several arms that are mixed together and an overall oval shape. The centre of the galaxy glows brightly. There are bright pink patches and filaments of dark red dust spread across the centre. Credit:ESA/Hubble & NASA, R. Chandar, J. Lee and the PHANGS-HST team & Beowulf | |
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| SoupPosted at 2023-11-13 21:09:31(53Wks ago) Report Permalink URL | ||
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| Astronomers find dozens of massive stars fleeing the Milky Way by Evan Gough, Universe Today  This illustration shows a star exploding as a supernova and subjecting its binary companion to the explosion’s brute force. If conditions are right, the binary companion can be ejected from the galaxy as a runaway star. Credit: NASA, ESA, Leah Hustak (STScI) The Milky Way can't hold onto all of its stars. Some of them get ejected into intergalactic space and spend their lives on an uncertain journey. A team of astronomers took a closer look at the most massive of these runaway stars to see what they could find out how they get ejected. When astronomers observe a field of stars in the Milky Way, one of the things they measure is the velocity distribution. The overall velocity distribution of the stellar population reflects the rotation of the galaxy. And when a star isn't harmonized with the galaxy's rotation, it catches astronomers' attention. A team of astronomers working with two catalogues of massive stars found a whole bunch of stars moving differently than the galaxy. They're runaway stars that are on their way out of the galaxy. The new findings are in a paper titled "Galactic runaway O and Be stars found using Gaia DR3." It's forthcoming in the journal Astronomy and Astrophysics, and the lead author is Mar Carretero Castrillo, a post-grad researcher in the Department of Quantum Physics and Astrophysics, Institute of Cosmos Sciences, University of Barcelona. Castrillo and her colleagues based their work on two stellar catalogues. They're the Galactic O-Star Catalog (GOSC) and the Be Star Spectra (BeSS). They're both catalogues of different types of massive stars: O-type stars and Be-type stars, and their sub-types. The researchers also used data from Gaia, the ESA's powerful star-measuring spacecraft. It employs astrometry to measure the positions, distances, and motions of one billion stars. Gaia's mission is changing astronomy by providing accurate, robust data that other researchers can use in their own research. This paper is based on a combination of Gaia data and data from the two catalogues. Nobody knows how many runaway stars are on their way out of our galaxy, but astronomers keep finding more of them. Some estimates say there are 10 million runaway stars fleeing the Milky Way, but we don't know for sure. It may depend on the mechanism that drives them away, and that's something astrophysicists don't fully understand.  This is Zeta Ophiuchi, a runaway star observed by Spitzer. The star is creating a bow shock as it travels through an interstellar dust cloud. A new study found dozens of new runaway stars in the Milky Way. Credit: NASA/JPL-Caltech This study aims to shed some light on the runaway star phenomenon by looking specifically at massive stars. "A relevant fraction of massive stars are runaway stars. These stars move with a significant peculiar velocity with respect to their environment," the authors explain. They set out to discover and characterize the runaway massive and early-type stars in both of the catalogues by examining Gaia data. "Massive early-type OB stars are the most luminous stars in the Milky Way," they explain. OB stars are not only massive and young, they're extremely hot. They form in loosely organized groups with one another called OB associations. Because they're young and hot, they don't last long. They're important in astronomy because they're so massive and energetic and because many of them explode as supernovae. That's why there are specific catalogues dedicated to them. The team cross-referenced Gaia data with the GOSC and BeSS catalogues and came up with 417 O-type stars and 1335 Be-type stars present in both Gaia and the catalogues, respectively. Out of those, they found 106 type O runaway stars, which is 25.4 % of the stars in the GOSC catalogue. Forty-two of them are newly identified. They found 69 Be runaway stars, which represent 5.2% of the stars in the Be-type star catalogue. Forty-seven of these are newly identified. Overall, the type-O stars move faster than the Be-type stars. Why do massive stars make up such a high proportion of runaway stars? There are two competing theories that attempt to explain runaway stars, and both involve massive stars. One is the dynamical ejection scenario (DES), and the other is the binary supernova scenario (BSS). OB stars often form in binary pairs. In the BSS, one star explodes as a supernova, and the explosion kicks the other star. If the situation is right, the surviving star is given enough energy in the right direction that it can escape from its bond with its partner, which is now a neutron star or a black hole. It can also escape the gravitational pull of the Milky Way. If that happens, it begins its long journey into intergalactic space.  This JWST image shows the Tarantula Nebula, with the young star cluster R136 at its center. R136 contains many of the most massive stars known. This dense region full of massive young stars is the type of environment that can lead to dynamical ejection. Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team In the DES, there's no dramatic supernova explosion. Instead, a star in a compact, densely packed region experiences gravitational interactions with other stars. Encounters between binary and single stars can produce runaways, and so can encounters between two binary pairs. The OB associations where O-type and B-type stars tend to form are the types of dense environments that can trigger runaway stars. Since most of these stars are massive, most of the runaway stars are, too. Scientists have been wondering about the two scenarios and debating them for decades. Both scenarios can produce stars with enough velocity to escape the galaxy. In studying their sample of 175 runaway stars, the researchers found that their data favors one explanation over the other. "The higher percentages and higher velocities found for O-type compared to Be-type runaways underline that the dynamical ejection scenario is more likely than the binary supernova scenario," they write. The percentages of spectral types represented in runaway stars help explain their conclusion. 25% of the O-type stars in their sample are runaways versus 5% of the Be-type. Other studies have come up with different numbers, but as the authors point out, "there is agreement in the sense that the percentage of runaway O stars is significantly higher than for B or Be stars." Previous research shows that O-type runaway stars have higher velocities than B and Be-type stars. Previous research also shows that dynamical ejection often results in faster, more massive runaways than the binary supernova scenario. "The GOSC-Gaia DR3 stars have higher velocities in general than those in BeSS-Gaia DR3," the authors explain, which lines up with the previous research. "This reinforces the dominance of the DES scenario versus the BSS one," they conclude. | |
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| SoupPosted at 2023-11-14 02:54:09(53Wks ago) Report Permalink URL | ||
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| If you account for the Laniakea supercluster, the Hubble tension might be even larger by Brian Koberlein, Universe Today  Illustration of the Laniakea supercluster. Credit: Andrew Z. Colvin One of the great unsolved mysteries of cosmology is known as the Hubble tension. It stems from our inability to pin down the precise rate of cosmic expansion. There are several ways to calculate this expansion, from observing distant supernovae to measuring the Doppler shift of maser light near supermassive black holes, and they all give slightly different results. Maybe we don't fully understand the structure of the universe, or maybe our view of the heavens is biased given that we are located deep within a galactic supercluster. As a new study shows, the bias problem is even worse than we thought. If we were floating deep in space, far away from any galaxies, then our view of cosmic expansion would be free of gravitational influences and we could better see how distant galaxies move away from us. Since we are part of a local cluster of galaxies, we have a bit of bias in our data. This is why many local galaxies are blue-shifted. The universe isn't contracting near us, we're just in a galactic gravitational well. We can easily account for this bias, so it isn't a problem. However, given the Hubble tension, a team recently looked for gravitational biases beyond the local group, hoping it would solve the issue. The work is published on the arXiv preprint server. They looked at the largest gravitational structure we're a part of, known as the Laniakea Supercluster. It is a massive cluster of galaxies more than 520 million light-years across, containing more than 100,000 galaxies, including the Milky Way. Our local group is being pulled toward the heart of Laniakea, and thus our motion through the universe could skew our observations of cosmic expansion.  Observations show a statistical bias in the data. Credit: Giani, et al When the team measured the gravitational influence of the supercluster as a whole, they found it does bias our observations by about 2%–3%. But it's biased in the wrong direction. In other words, by not taking the effect of Laniakea into account, the Hubble tension seemed smaller than it actually is. These new results show that the tension is 2%–3% greater than we thought. Even some of the more recent Hubble constant measurements that seemed encouraging aren't enough to account for the Laniakea bias. Removing subtle biases from our cosmological data is challenging, so it is possible that further observations may swing the results back in the right direction. But we can't rely on bias alone to solve this mystery. Clearly, something subtle and strange is going on, and the solution isn't obvious. It will take a great deal more study to understand Hubble's tension. | |
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| Jase1Posted at 2023-11-15 14:03:38(53Wks ago) Report Permalink URL | ||
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|  This side-by-side comparison shows observations of the Southern Ring Nebula in near-infrared light, at left, and mid-infrared light, at right, from NASA’s Webb Telescope. This scene was created by a white dwarf star – the remains of a star like our Sun after it shed its outer layers and stopped burning fuel through nuclear fusion. Those outer layers now form the ejected shells all along this view. In the Near-Infrared Camera (NIRCam) image, the white dwarf appears to the lower left of the bright, central star, partially hidden by a diffraction spike. The same star appears – but brighter, larger, and redder – in the Mid-Infrared Instrument (MIRI) image. This white dwarf star is cloaked in thick layers of dust, which make it appear larger. The brighter star in both images hasn’t yet shed its layers. It closely orbits the dimmer white dwarf, helping to distribute what it’s ejected. Over thousands of years and before it became a white dwarf, the star periodically ejected mass – the visible shells of material. As if on repeat, it contracted, heated up – and then, unable to push out more material, pulsated. Stellar material was sent in all directions – like a rotating sprinkler – and provided the ingredients for this asymmetrical landscape. Today, the white dwarf is heating up the gas in the inner regions – which appear blue at left and red at right. Both stars are lighting up the outer regions, shown in orange and blue, respectively. The images look very different because NIRCam and MIRI collect different wavelengths of light. NIRCam observes near-infrared light, which is closer to the visible wavelengths our eyes detect. MIRI goes farther into the infrared, picking up mid-infrared wavelengths. The second star appears more clearly in the MIRI image, because this instrument can see the gleaming dust around it. The stars – and their layers of light – steal more attention in the NIRCam image, while dust plays the lead in the MIRI image, specifically dust that is illuminated. Peer at the circular region at the center of both images. Each contains a wobbly, asymmetrical belt of material. This is where two “bowls” that make up the nebula meet. (In this view, the nebula is at a 40-degree angle.) This belt is easier to spot in the MIRI image – look for the yellowish circle – but is also visible in the NIRCam image. The light that travels through the orange dust in the NIRCam image – which looks like spotlights – disappears at longer infrared wavelengths in the MIRI image. In near-infrared light, stars have more prominent diffraction spikes because they are so bright at these wavelengths. In mid-infrared light, diffraction spikes also appear around stars, but they are fainter and smaller (zoom in to spot them). Physics is the reason for the difference in the resolution of these images. NIRCam delivers high-resolution imaging because these wavelengths of light are shorter. MIRI supplies medium-resolution imagery because its wavelengths are longer – the longer the wavelength, the coarser the images are. But both deliver an incredible amount of detail about every object they observe – providing never-before-seen vistas of the universe. NASA, ESA, CSA, STScI | |
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| Jase1Posted at 2023-11-15 17:44:17(53Wks ago) Report Permalink URL | ||
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|  A transmission spectrum made from a single observation using Webb’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) reveals atmospheric characteristics of the hot gas giant exoplanet WASP-96 b. A transmission spectrum is made by comparing starlight filtered through a planet’s atmosphere as it moves across the star, to the unfiltered starlight detected when the planet is beside the star. Each of the 141 data points (white circles) on this graph represents the amount of a specific wavelength of light that is blocked by the planet and absorbed by its atmosphere. In this observation, the wavelengths detected by NIRISS range from 0.6 microns (red) to 2.8 microns (in the near-infrared). The amount of starlight blocked ranges from about 13,600 parts per million (1.36 percent) to 14,700 parts per million (1.47 percent). Researchers are able to detect and measure the abundances of key gases in a planet’s atmosphere based on the absorption pattern – the locations and heights of peaks on the graph: each gas has a characteristic set of wavelengths that it absorbs. The temperature of the atmosphere can be calculated based in part on the height of the peaks: a hotter planet has taller peaks. Other characteristics, like the presence of haze and clouds, can be inferred based on the overall shape of different portions of the spectrum. The gray lines extending above and below each data point are error bars that show the uncertainty of each measurement, or the reasonable range of actual possible values. For a single observation, the error on these measurements is remarkably small. The blue line is a best-fit model that takes into account the data, the known properties of WASP-96 b and its star (e.g., size, mass, temperature), and assumed characteristics of the atmosphere. Researchers can vary the parameters in the model – changing unknown characteristics like cloud height in the atmosphere and abundances of various gases – to get a better fit and further understand what the atmosphere is really like. The difference between the best-fit model shown here and the data simply reflects the additional work to be done in analyzing and interpreting the data and the planet. Although full analysis of the spectrum will take additional time, it is possible to draw a number of preliminary conclusions. The labeled peaks in the spectrum indicate the presence of water vapor. The height of the water peaks, which is less than expected based on previous observations, is evidence for the presence of clouds that suppress the water vapor features. The gradual downward slope of the left side of the spectrum (shorter wavelengths) is indicative of possible haze. The height of the peaks along with other characteristics of the spectrum is used to calculate an atmospheric temperature of about 1350°F (725°C). This is the most detailed infrared exoplanet transmission spectrum ever collected, the first transmission spectrum that includes wavelengths longer than 1.6 microns with such high resolution and accuracy, and the first to cover the entire wavelength range from 0.6 microns (visible red light) to 2.8 microns (near-infrared) in a single shot. The speed with which researchers have been able to make confident interpretations of the spectrum is further testament to the quality of the data. The observation was made using NIRISS’s Single-Object Slitless Spectroscopy (SOSS) mode, which involves capturing the spectrum of a single bright object, like the star WASP-96, in a field of view. WASP-96 b is a hot gas giant exoplanet that orbits a Sun-like star roughly 1,150 light-years away, in the constellation Phoenix. The planet orbits extremely close to its star (less than 1/20th the distance between Earth and the Sun) and completes one orbit in less than 3½ Earth-days. The planet’s discovery, based on ground-based observations, was announced in 2014. The star, WASP-96, is somewhat older than the Sun, but is about the same size, mass, temperature, and color. The background illustration of WASP-96 b and its star is based on current understanding of the planet from both NIRISS spectroscopy and previous ground- and space-based observations. Webb has not captured a direct image of the planet or its atmosphere. NIRISS was contributed by the Canadian Space Agency. The instrument was designed and built by Honeywell in collaboration with the Université de Montréal and the National Research Council Canada. NASA, ESA, CSA, STScI | |
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| Jase1Posted at 2023-11-16 16:05:41(53Wks ago) Report Permalink URL | ||
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|  Astronomers using NASA’s James Webb Space Telescope combined the capabilities of the telescope’s two cameras to create a never-before-seen view of a star-forming region in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI), this combined image reveals previously invisible areas of star birth. What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region known as NGC 3324. Called the Cosmic Cliffs, this rim of a gigantic, gaseous cavity is roughly 7,600 light-years away. The cavernous area has been carved from the nebula by the intense ultraviolet radiation and stellar winds from extremely massive, hot, young stars located in the center of the bubble, above the area shown in this image. The high-energy radiation from these stars is sculpting the nebula’s wall by slowly eroding it away. NIRCam – with its crisp resolution and unparalleled sensitivity – unveils hundreds of previously hidden stars, and even numerous background galaxies. In MIRI’s view, young stars and their dusty, planet-forming disks shine brightly in the mid-infrared, appearing pink and red. MIRI reveals structures that are embedded in the dust and uncovers the stellar sources of massive jets and outflows. With MIRI, the hydrocarbons and other chemical compounds on the surface of the ridges glow, giving the appearance of jagged rocks. Several prominent features in this image are described below. -- The faint “steam” that appears to rise from the celestial “mountains” is actually hot, ionized gas and hot dust streaming away from the nebula due to intense, ultraviolet radiation. -- Peaks and pillars rise above the glowing wall of gas, resisting the blistering ultraviolet radiation from the young stars. -- Bubbles and cavities are being blown by the intense radiation and stellar winds of newborn stars. -- Protostellar jets and outflows, which appear in gold, shoot from dust-enshrouded, nascent stars. MIRI uncovers the young, stellar sources producing these features. For example, a feature at left that looks like a comet with NIRCam is revealed with MIRI to be one cone of an outflow from a dust-enshrouded, newborn star. -- A “blow-out” erupts at the top-center of the ridge, spewing material into the interstellar medium. MIRI sees through the dust to unveil the star responsible for this phenomenon. -- An unusual “arch,” looking like a bent-over cylinder, appears in all wavelengths shown here. This period of very early star formation is difficult to capture because, for an individual star, it lasts only about 50,000 to 100,000 years – but Webb’s extreme sensitivity and exquisite spatial resolution have chronicled this rare event. NGC 3324 was first catalogued by James Dunlop in 1826. Visible from the Southern Hemisphere, it is located at the northwest corner of the Carina Nebula (NGC 3372), which resides in the constellation Carina. The Carina Nebula is home to the Keyhole Nebula and the active, unstable supergiant star called Eta Carinae. NIRCam was built by a team at the University of Arizona and Lockheed Martin’s Advanced Technology Center. MIRI was contributed by ESA and NASA, with the instrument designed and built by a consortium of nationally funded European Institutes (The MIRI European Consortium) in partnership with JPL and the University of Arizona. | |
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| BeowulfPosted at 2023-11-16 17:51:33(53Wks ago) Report Permalink URL | ||
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|  This spectacular image shows a region called G35.2-0.7N, which is known as a hotbed of high-mass star formation. The kind of stars that form here are so massive that they will end their lives as destructive supernovae. However, even as they form they greatly impact their surroundings. At least one B-type star — the second most massive type — lurks within the region pictured here, and a powerful protostellar jet that it is launching towards us is the source of the spectacular light show. The image was taken with the Wide Field Camera 3 (WFC3), which is mounted on the NASA/ESA Hubble Space Telescope, and the region G35.2-0.7N lies around 7200 light-years from Earth in the constellation Aquila. This beautiful picture was assembled using data that were collected primarily for very specific research purposes, as are many of the Hubble Pictures of the Week. The research conducted using these data included measuring the extent of ionisation in the jets being blasted out of the protostar buried within G35.2-0.7N. Ionisation is a process by which atoms or molecules become charged, often because they are in such a high-energy environment that they have lost some of their electrons (the tiny negatively charged particles that orbit nuclei in atoms and molecules). Protostellar jets are enormous collimated beams of matter that are ejected from protostars. Collimated simply means that the matter is ejected in parallel (column-like) streams, which in turn means that the jets do not spread out much, but extend out very far in relatively straight lines. The visual result of the ejected matter is the glorious display visible in this image. Much of the nebula is dark, with light being blocked from Hubble’s view by the rich dust clouds that produce these massive stars. Near the very centre can be seen the location of the star and the jet of material it is emitting. The small, bright orange streak there is a cavity in the dust carved out by the ferocity of the jet as it streams towards us. By breaking through its dusty cocoon, the jet reveals light from the protostar, but there is still so much dust that the light is “reddened” to a fiery orange. The massive protostar lies at the very lower-left tip of this cavity. [Image Description: A nebula with stars. Dense clouds of dust and gas cover the left-hand side and a filament crosses the centre horizontally. Billowing streams of gas and dust in various colours emerge from around the centre. The very centre of the image is permeated with glowing orange regions. Many blue stars with cross-shaped spikes lie in the foreground, and small point-like stars are visible beyond the clouds. Credit: ESA/Hubble & NASA, R. Fedriani, J. Tan & the great Master Beowulf | |
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| Jase1Posted at 2023-11-20 13:57:51(52Wks ago) Report Permalink URL | ||
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|  What’s left over after a massive star reaches the end of its life I hear you ask? Take a look for yourself. This Picture of the Week shows a small but very intricate portion of the Vela supernova remnant, the violent and yet beautiful aftermath of an explosive stellar death. This dramatic scene played out around 11 000 years ago when a massive star in the constellation Vela went supernova. During this violent event, the star would have shined so brightly that it could be seen during the day. The detailed and stunning view of both the gaseous filaments in the remnant and the bright blue stars in the foreground were captured using the 286-million-pixel OmegaCAM at the VLT Survey Telescope, hosted at ESO’s Paranal Observatory. OmegaCAM can take images through several filters that each let the telescope observe the light emitted in a distinct colour. To capture this image, four filters have been used, represented here by a combination of magenta, blue, green and red. Credit: ESO/VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit | |
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| EliteZukieNr1Posted at 2023-11-20 14:41:11(52Wks ago) Report Permalink URL | ||
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| EliteZukieNr1Posted at 2023-11-20 14:53:40(52Wks ago) Report Permalink URL | ||
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| The slider tool above contrasts Webb’s two views of M83 as observed with the MIRI instrument (left) and the NIRCam instrument (right).   ESA/Webb, NASA & CSA, A. Adamo | |
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| Jase1Posted at 2023-11-21 11:46:19(52Wks ago) Report Permalink URL | ||
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|  This image of Jupiter from NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) shows stunning details of the majestic planet in infrared light. In this image, brightness indicates high altitude. The numerous bright white "spots" and "streaks" are likely very high-altitude cloud tops of condensed convective storms. Auroras, appearing in red in this image, extend to higher altitudes above both the northern and southern poles of the planet. By contrast, dark ribbons north of the equatorial region have little cloud cover. In Webb’s images of Jupiter from July 2022, researchers recently discovered a narrow jet stream traveling 320 miles per hour (515 kilometers per hour) sitting over Jupiter’s equator above the main cloud decks.  Researchers using NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) have discovered a high-speed jet stream sitting over Jupiter’s equator, above the main cloud decks. At a wavelength of 2.12 microns, which observes between altitudes of about 12-21 miles (20-35 kilometers) above Jupiter’s cloud tops, researchers spotted several wind shears, or areas where wind speeds change with height or with distance, which enabled them to track the jet. This image highlights several of the features around Jupiter’s equatorial zone that, between one rotation of the planet (10 hours), are very clearly disturbed by the motion of the jet stream. NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael H. Wong (UC Berkeley), Joseph DePasquale (STScI) | |
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| Deep61Posted at 2023-11-21 21:49:51(52Wks ago) Report Permalink URL | ||
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| miokPosted at 2023-11-21 21:53:53(52Wks ago) Report Permalink URL | ||
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| Amazing Deep, looks like a NASA image! You caught on to this quickly. Keep em coming   | |
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| Deep61Posted at 2023-11-21 22:02:32(52Wks ago) Report Permalink URL | ||
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| I cannot even remember all the 20 odd steps to get that one lol | |
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| SoupPosted at 2023-11-21 23:39:01(52Wks ago) Report Permalink URL | ||
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| A radically new view on dwarf galaxies surrounding the Milky Way by Janine Fohlmeister, Leibniz Institute for Astrophysics Potsdam  Dwarf galaxies around the Milky Way. Credit: ESA/Gaia/DPAC Commonly thought to be long-lived satellites of our galaxy, a new study now finds indications that most dwarf galaxies might, in fact, be destroyed soon after their entry into the Galactic halo. Thanks to the latest catalog from ESA's Gaia satellite, an international team has now demonstrated that dwarf galaxies might be out of equilibrium. Published in the Monthly Notices of the Royal Astronomical Society, the study opens important questions on the standard cosmological model, particularly on the prevalence of dark matter in our nearest environment. It has long been assumed that the dwarf galaxies around the Milky Way are ancient satellites orbiting our galaxy for nearly 10 billion years. This required them to contain huge amounts of dark matter to protect them from the enormous tidal effects due to the gravitational pull of our galaxy. It was assumed that dark matter caused the large differences observed in the velocities of the stars within these dwarf galaxies. The latest Gaia data has now revealed a completely different view of dwarf galaxy properties. Astronomers from the Paris Observatory—PSL, the Center National de la Recherche Scientifique (CNRS), and the Leibniz Institute for Astrophysics Potsdam (AIP) were able to date the history of the Milky Way, thanks to the relationship that connects the orbital energy of an object to its epoch of entry into the halo, the time they became first captured by the Milky Way's gravitational field: Objects that arrived early, when the Milky Way was less massive, have lower orbital energies than recent arrivals. The orbital energies of most dwarf galaxies are surprisingly substantially larger than that of the Sagittarius dwarf galaxy that entered the halo 5 to 6 billion years ago. This implies that most dwarf galaxies arrived much more recently, less than three billion years ago.  Image from a simulation of the transformation of a gas-rich and rotation-dominated galaxy into a spherical dwarf galaxy. Here an analogue of the Sculptor dwarf galaxy is shown. Credit: Jianling Wang, François Hammer Such a recent arrival implies that the nearby dwarfs come from outside the halo, where almost all dwarf galaxies are observed to contain huge reservoirs of neutral gas. The gas-rich galaxies lost their gas when they collided with the hot gas of the Galactic halo. The violence of shocks and turbulence in the process completely changed the dwarf galaxies. While the previously gas-rich dwarf galaxies were dominated by the rotation of gas and stars, when they are transformed into gas-free systems, their gravity becomes balanced by the random motions of their remaining stars. Dwarf galaxies lose their gas in a process so violent that it puts them out of equilibrium, which means that how fast their stars move is no longer in balance with their gravitational acceleration. The combined effects of gas loss and gravitational shocks due to the dive into the galaxy nicely explain the widespread velocities of the stars within the dwarf galaxy remnant. One of the curiosities of this study is the role of dark matter. First, the absence of an equilibrium prevents any estimation of the dynamical mass of the Milky Way dwarfs and their dark matter content. Second, while in the previous scenario, dark matter protected the supposed stability of dwarf galaxies, invoking dark matter becomes rather awkward for objects out of balance. In fact, if the dwarf had already contained a lot of dark matter, it would have stabilized its initial rotating disk of stars, preventing the dwarf's transformation into a galaxy with random stellar motions as observed. The described recent arrival of dwarf galaxies and their transformations in the halo explain well many observed properties of these objects, in particular, why they have stars at large distances from their center. Their properties seem compatible with an absence of dark matter, contrary to the previous understanding of dwarf galaxies as the most dark-matter-dominated objects. Many questions now arise, such as: Where are the many dark-matter-dominated dwarf galaxies that the standard cosmological model expects around the Milky Way? How can we infer the dark matter content of a dwarf galaxy if equilibrium cannot be assumed? What other observations could discriminate between the proposed out-of-equilibrium dwarf galaxies and the classical picture with dark-matter-dominated dwarfs? | |
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