Jase1        Posted at 2023-11-23 13:31:46(52Wks ago) Report Permalink URL | ||
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|  NASA, ESA, CSA, STScI, and S. Crowe (University of Virginia) A star-forming region, named Sagittarius C (Sgr C), is seen in exceptional detail in this image from Nov. 20, 2023, thanks to the Near-Infrared Camera instrument on NASA’s James Webb Space Telescope. An estimated 500,000 stars shine in this image of the Sgr C region, along with some never-before-seen features astronomers have yet to explain. | |
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| Jase1Posted at 2023-11-27 12:40:41(51Wks ago) Report Permalink URL | ||
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|  There’s magic in this Picture of the Week; can you feel it? The strange geological formations protruding out of the desert floor are twisted and gnarled like old wizards’ hats, while the sky above is filled with thousands of stars and a myriad of mesmerising colours. This is Valle de la Luna — meaning “Valley of the Moon” — in the Chilean Atacama Desert, close to where the Atacama Large Millimeter/submillimeter Array (ALMA), in which ESO is a partner, is located. It’s easy to see where the valley gets its name from; the moon-like formations on the dried-up salt beds have been eroded by aeons of exposure to the elements and feel far more out of this world than of it. Its altitude and dry air, as well as its distance from civilisation, make it a great place for stargazing. This is particularly important for ALMA, as water vapour in the atmosphere can absorb the invisible light collected by this radio telescope. As the night unfolds, the sky comes alive with the glowing cascade of the Milky Way, illuminated by gas and stars. The vibrant red colour dancing across the Milky Way comes from hydrogen atoms distributed throughout our galaxy. | |
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| Jase1Posted at 2023-11-29 19:44:10(51Wks ago) Report Permalink URL | ||
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|  NASA’s James Webb Space Telescope has gazed at the Crab Nebula in the search for answers about the supernova remnant’s origins. Webb’s NIRCam (Near-Infrared Camera) and MIRI (Mid-Infrared Instrument) have revealed new details in infrared light. Similar to the Hubble optical wavelength image released in 2005, with Webb the remnant appears comprised of a crisp, cage-like structure of fluffy red-orange filaments of gas that trace doubly ionized sulfur (sulfur III). Among the remnant’s interior, yellow-white and green fluffy ridges form large-scale loop-like structures, which represent areas where dust particles reside. The area within is comprised of translucent, milky material. This white material is synchrotron radiation, which is emitted across the electromagnetic spectrum but becomes particularly vibrant thanks to Webb’s sensitivity and spatial resolution. It is generated by particles accelerated to extremely high speeds as they wind around magnetic field lines. Trace the synchrotron radiation throughout the majority of the Crab Nebula’s interior. Locate the wisps that follow a ripple-like pattern in the middle. In the center of this ring-like structure is a bright white dot: a rapidly rotating neutron star. Further out from the core, follow the thin white ribbons of the radiation. The curvy wisps are closely grouped together, following different directions that mimic the structure of the pulsar’s magnetic field. Note how certain gas filaments are bluer in color. These areas contain singly ionized iron (iron II). NASA, ESA, CSA, STScI, Tea Temim (Princeton University) | |
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| Jase1Posted at 2023-11-30 17:18:47(51Wks ago) Report Permalink URL | ||
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|  X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI/AURA; IR:NASA/JPL/Caltech; Image Processing: NASA/CXC/SAO/N. Wolk A group of dead stars known as “spider pulsars” are obliterating companion stars within their reach. Data from NASA’s Chandra X-ray Observatory of the globular cluster Omega Centauri is helping astronomers understand how these spider pulsars prey on their stellar companions. A pulsar is the spinning dense core that remains after a massive star collapses into itself to form a neutron star. Rapidly rotating neutron stars can produce beams of radiation. Like a rotating lighthouse beam, the radiation can be observed as a powerful, pulsing source of radiation, or pulsar. Some pulsars spin around dozens to hundreds of times per second, and these are known as millisecond pulsars. Spider pulsars are a special class of millisecond pulsars, and get their name for the damage they inflict on small companion stars in orbit around them. Through winds of energetic particles streaming out from the spider pulsars, the outer layers of the pulsar’s companion stars are methodically stripped away. Astronomers recently discovered 18 millisecond pulsars in Omega Centauri — located about 17,700 light-years from Earth — using the Parkes and MeerKAT radio telescopes. A pair of astronomers from the University of Alberta in Canada then looked at Chandra data of Omega Centauri to see if any of the millisecond pulsars give off X-rays. They found 11 millisecond pulsars emitting X-rays, and five of those were spider pulsars concentrated near the center of Omega Centauri. The researchers next combined the data of Omega Centauri with Chandra observations of 26 spider pulsars in 12 other globular clusters.  X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI/AURA; Image Processing: NASA/CXC/SAO/N. Wolk There are two varieties of spider pulsars based on the size of the star being destroyed. “Redback” spider pulsars are damaging companion stars weighing between a tenth and a half the mass of the Sun. Meanwhile, the “black widow” spider pulsars are damaging companion stars with less than 5 percent of the Sun’s mass. The team found a clear difference between the two classes of spider pulsars, with the redbacks being brighter in X-rays than the black widows, confirming previous work. The team is the first to show a general correlation between X-ray brightness and companion mass for spider pulsars, with pulsars that produce more X-rays being paired with more massive companions. This gives clear evidence that the mass of the companion to spider pulsars influences the X-ray dose the star receives. The X-rays detected by Chandra are mainly thought to be generated when the winds of particles flowing away from the pulsars collide with winds of matter blowing away from the companion stars and produce shock waves, similar to those produced by supersonic aircraft. Spider pulsars are typically separated from their companions by only about one to 14 times the distance between the Earth and Moon. This close proximity — cosmically speaking — causes the energetic particles from the pulsars to be particularly damaging to their companion stars. This finding agrees with theoretical models that scientists have developed. Because more massive stars produce a denser wind of particles, there is a stronger shock — producing brighter X-rays — when their wind collides with the particles from the pulsar. The proximity of the companion stars to their pulsars means the X-rays can cause significant damage to the stars, along with the pulsar’s wind. Chandra’s sharp X-ray vision is crucial for studying millisecond pulsars in globular clusters because they often contain large numbers of X-ray sources in a small part of the sky, making it difficult to distinguish sources from each other. Several of the millisecond pulsars in Omega Centauri have other, unrelated X-ray sources only a few arc seconds away. (One arc second is the apparent size of a penny seen at a distance of 2.5 miles.) The paper describing these results will be published in the December issue of the Monthly Notices of the Royal Astronomical Society, and a preprint of the accepted paper is available online. The authors of the paper are Jiaqi (Jake) Zhao and Craig Heinke, both from the University of Alberta in Canada. NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts. | |
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| BeowulfPosted at 2023-12-04 17:42:07(50Wks 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 & Beowulf | |
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| SoupPosted at 2023-12-05 02:48:30(50Wks ago) Report Permalink URL | ||
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| Do we live in a giant void? That could solve the puzzle of the universe's expansion, research suggests by Indranil Banik, The Conversation  Credit: Pablo Carlos Budassi/wikipedia, CC BY-SA One of the biggest mysteries in cosmology is the rate at which the universe is expanding. This can be predicted using the standard model of cosmology, also known as Lambda-cold dark matter (ΛCDM). This model is based on detailed observations of the light left over from the Big Bang—the so-called cosmic microwave background (CMB). The universe's expansion makes galaxies move away from each other. The further away they are from us, the more quickly they move. The relationship between a galaxy's speed and distance is governed by Hubble's constant, which is about 43 miles (70 km) per second per megaparsec (a unit of length in astronomy). This means that a galaxy gains about 50,000 miles per hour for every million light years it is away from us. But unfortunately for the standard model, this value has recently been disputed, leading to what scientists call the Hubble tension. When we measure the expansion rate using nearby galaxies and supernovas (exploding stars), it is 10% larger than when we predict it based on the CMB. In our new paper published in the Monthly Notices of the Royal Astronomical Society, we present one possible explanation: that we live in a giant void in space (an area with below average density). We show that this could inflate local measurements through outflows of matter from the void. Outflows would arise when denser regions surrounding a void pull it apart—they'd exert a bigger gravitational pull than the lower density matter inside the void. In this scenario, we would need to be near the center of a void about a billion light years in radius and with density about 20% below the average for the universe as a whole—so not completely empty. Such a large and deep void is unexpected in the standard model—and therefore controversial. The CMB gives a snapshot of structure in the infant universe, suggesting that matter today should be rather uniformly spread out. However, directly counting the number of galaxies in different regions does indeed suggest we are in a local void. Tweaking the laws of gravity We wanted to test this idea further by matching many different cosmological observations by assuming that we live in a large void that grew from a small density fluctuation at early times. To do this, our model didn't incorporate ΛCDM but an alternative theory called Modified Newtonian Dynamics (MOND). MOND was originally proposed to explain anomalies in the rotation speeds of galaxies, which is what led to the suggestion of an invisible substance called "dark matter." MOND instead suggests that the anomalies can be explained by Newton's law of gravity breaking down when the gravitational pull is very weak—as is the case in the outer regions of galaxies. The overall cosmic expansion history in MOND would be similar to the standard model, but structure (such as galaxy clusters) would grow faster in MOND. Our model captures what the local universe might look like in a MOND universe. And we found it would allow local measurements of the expansion rate today to fluctuate depending on our location. Recent galaxy observations have allowed a crucial new test of our model based on the velocity it predicts at different locations. This can be done by measuring something called the bulk flow, which is the average velocity of matter in a given sphere, dense or not. This varies with the radius of the sphere, with recent observations showing it continues out to a billion light years. Interestingly, the bulk flow of galaxies on this scale has quadruple the speed expected in the standard model. It also seems to increase with the size of the region considered—opposite to what the standard model predicts. The likelihood of this being consistent with the standard model is below one in a million.  CMB temperature fluctuations (color differences). Credit: NASA This prompted us to see what our study predicted for the bulk flow. We found it yields a quite good match to the observations. That requires that we are fairly close to the void center, and the void being most empty at its center. Case closed? Our results come at a time when popular solutions to the Hubble tension are in trouble. Some believe we just need more precise measurements. Others think it can be solved by assuming the high expansion rate we measure locally is actually the correct one. But that requires a slight tweak to the expansion history in the early universe so the CMB still looks right. Unfortunately, an influential review highlights seven problems with this approach. If the universe expanded 10% faster over the vast majority of cosmic history, it would also be about 10% younger—contradicting the ages of the oldest stars. The existence of a deep and extended local void in the galaxy number counts and the fast observed bulk flows strongly suggest that structure grows faster than expected in ΛCDM on scales of tens to hundreds of millions of light years. Interestingly, we know that the massive galaxy cluster El Gordo formed too early in cosmic history and has too high a mass and collision speed to be compatible with the standard model. This is yet more evidence that structure forms too slowly in this model. Since gravity is the dominant force on such large scales, we most likely need to extend Einstein's theory of gravity, general relativity—but only on scales larger than a million light years. However, we have no good way to measure how gravity behaves on much larger scales—there are no gravitationally bound objects that huge. We can assume General Relativity remains valid and compare with observations, but it is precisely this approach that leads to the very severe tensions currently faced by our best model of cosmology. Einstein is thought to have said that we cannot solve problems with the same thinking that led to the problems in the first place. Even if the required changes are not drastic, we could well be witnessing the first reliable evidence for more than a century that we need to change our theory of gravity. | |
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| Jase1Posted at 2023-12-06 17:26:10(50Wks ago) Report Permalink URL | ||
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|  Astronomers have spotted a rare burst of light that’s thought to be one of the Universe’s brightest phenomena. But it has only served to deepen the mystery of what causes these unusual events. Luminous Fast Blue Optical Transients (LFBOTs) are very blue in colour and evolve rapidly, reaching peak brightness and fading away in a matter of days. Their short-lived nature makes them difficult to spot, and the first, dubbed ‘the Cow’, was only discovered in 2018. Since then, they’ve been spotted at a rate of about one per year, mostly in the spiral arms of local galaxies. That led astronomers to believe they were unusual supernovae generated by huge but short-lived stars. This latest event, though – called AT2023fhn or ‘the Finch’, and first observed on 10 April 2023 – appears to have occurred not within a local galaxy, but in the space between two. “The more we learn about Luminous Fast Blue Optical Transients, the more they surprise us,” says European Space Agency research fellow Ashley Chrimes, who led the study. “We’ve now shown that LFBOTs can occur a long way from the centre of the nearest galaxy, and the location of the Finch is not what we expect for any kind of supernova.”  The blue flash of the Luminous Fast Blue Optical Transient known as ‘the Finch’. Click on the link to zoom in. Credit: NASA/ESA/NSF’s NOIRLab/Mark Garlick/Mahdi Zamani, NASA/ESA/STScI/Ashley Chrimes (ESA-ESTEC/Radboud University) What else could ‘the Finch’ be? It could be that the event is a collision between two neutron stars, where one is highly magnetised and so amplifies the explosion. Alternatively, Luminous Fast Blue Optical Transients could be stars being torn apart by intermediate black holes with a mass between 100 and 1,000 times that of the Sun. These are thought to lie in globular clusters, which would evade Hubble’s view but could be found in future observations by the James Webb Space Telescope. “The discovery poses many more questions than it answers,” says Chrimes. “More work is needed to figure out which of the many possible explanations is the right one.” A view of the Milky Way rising over the Vera C. Rubin Observatory. Credit: Vera C. Rubin Observatory/NOIRLab/AURA/NSF Rather than the never-changing cosmos that centuries of astronomers thought they were exploring, modern surveys show a surprising variety of things that go bang in the night. The Vera C Rubin Observatory will soon start scanning the whole sky every three nights with a 8.4-metre telescope. In its first tranche of data will be more supernovae than we’ve recorded in human history, all sorts of exotic objects and – hopefully – plenty of Luminous Fast Blue Optical Transients. Almost all the mechanisms suggested for Luminous Fast Blue Optical Transients, from colliding black holes to supernovae, must happen out in the Universe, and they should show up in Rubin’s data. Exciting times, whatever the Finch turns out to be. | |
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| Jase1Posted at 2023-12-07 17:20:27(50Wks ago) Report Permalink URL | ||
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|  The mated Russian-built Zarya (left) and U.S.-built Unity modules are backdropped against the blackness of space and Earth’s horizon shortly after leaving Endeavour’s cargo bay on Dec. 13, 1998. A few days earlier, on Dec. 6, 1998, the space shuttle Endeavour, mission STS-88, launched from NASA’s Kennedy Space Center in Florida carrying the Unity connecting module and two pressurized mating adapters. The same day, the STS-88 crew captured the Russian Zarya module, launched Nov. 20, and mated it with the Unity node. Unity was the first piece of the International Space Station provided by the United States. The components in the current space station were built in various countries around the world, with each piece performing once connected in space by complex robotics systems and humans in spacesuits—a testament to teamwork and cultural coordination. | |
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| SoupPosted at 2023-12-11 23:37:34(49Wks ago) Report Permalink URL | ||
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| Asteroid will pass in front of bright star Betelgeuse to produce a rare eclipse visible to millions By Marcia Dunn  This image made with the Hubble Space Telescope and released by NASA on Aug. 10, 2020 shows the star Alpha Orionis, or Betelgeuse, a red supergiant. The star, one of the biggest and brightest in the night sky, will momentarily vanish as an asteroid passes in front of it late Monday, Dec. 11, 2023, into early Tuesday. The event should be visible to millions of people along a narrow corridor stretching from central Asia’s Tajikistan and Armenia, across Turkey, Greece, Italy and Spain, all the way to Miami and the Florida Keys, and, finally, Mexico. (Andrea Dupree (Harvard-Smithsonian CfA), Ronald Gilliland (STScI), NASA and ESA via AP) One of the biggest and brightest stars in the night sky will momentarily vanish as an asteroid passes in front of it to produce a one-of-a-kind eclipse. The rare and fleeting spectacle, late Monday into early Tuesday, should be visible to millions of people along a narrow path stretching from central Asia's Tajikistan and Armenia, across Turkey, Greece, Italy and Spain, to Miami and the Florida Keys and finally, to parts of Mexico. The star is Betelgeuse, a red supergiant in the constellation Orion. The asteroid is Leona, a slowly rotating, oblong space rock in the main asteroid belt between Mars and Jupiter. Astronomers hope to learn more about Betelgeuse and Leona through the eclipse, which is expected to last no more than 15 seconds. By observing an eclipse of a much dimmer star by Leona in September, a Spanish-led team recently estimated the asteroid to be about 34 miles wide and 50 miles long (55 kilometers wide and 80 kilometers long). There are lingering uncertainties over those predictions as well as the size of the star and its expansive atmosphere. It's unclear if the asteroid will obscure the entire star, producing a total eclipse. Rather, the result could be a "ring of fire" eclipse with a miniscule blazing border around the star. If it's a total eclipse, astronomers aren't sure how many seconds the star will disappear completely, perhaps up to 10 seconds. "Which scenario we will see is uncertain, making the event even more intriguing," said astronomer Gianluca Masa, founder of the Virtual Telescope Project, which will provide a live webcast from Italy. An estimated 700 light-years away, Betelgeuse is visible with the naked eye. Binoculars and small telescopes will enhance the view. A light-year is 5.8 trillion miles. Betelgeuse is thousands of times brighter than our sun and some 700 times bigger. It's so huge that if it replaced our sun, it would stretch beyond Jupiter, according to NASA. At just 10 million years old, Betelgeuse is considerably younger than the 4.6 billion-year-old sun. Scientists expect Betelgeuse to be short-lived, given its mass and the speed at which it's burning through its material. After countless centuries of varying brightness, Betelgeuse dimmed dramatically in 2019 when a huge bunch of surface material was ejected into space. The resulting dust cloud temporarily blocked the starlight, NASA said, and within a half year, Betelgeuse was as bright as before. Scientists expect Betelgeuse to go supernova in a violent explosion within 100,000 years. | |
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| Jase1Posted at 2023-12-12 14:25:55(49Wks ago) Report Permalink URL | ||
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|  NASA’s Hubble Space Telescope can resolve individual stars in the densely-packed cores of globular clusters like NGC 2210. ESA/Hubble & NASA, A. Sarajedini This striking Hubble Space Telescope image shows the densely packed globular cluster known as NGC 2210, which is situated in the Large Magellanic Cloud (LMC). The LMC lies about 157,000 light-years from Earth and is a so-called satellite galaxy of the Milky Way, meaning that the two galaxies are gravitationally bound. Globular clusters are very stable, tightly bound clusters of thousands or even millions of stars. Their stability means that they can last a long time, and therefore globular clusters are often studied to investigate potentially very old stellar populations. In fact, 2017 research using some of the data that were also used to build this image revealed that a sample of LMC globular clusters were incredibly close in age to some of the oldest stellar clusters found in the Milky Way’s halo. They found that NGC 2210 specifically probably clocks in at around 11.6 billion years old. Even though this is only a couple of billion years younger than the universe itself, it made NGC 2210 by far the youngest globular cluster in their sample. All other LMC globular clusters studied in the same work were found to be even older, with four of them over 13 billion years old. This tells astronomers that the oldest globular clusters in the LMC formed contemporaneously with the oldest clusters in the Milky Way, even though the two galaxies formed independently. As well as being a source of interesting research, this old-but-relatively-young cluster is also extremely beautiful, with its highly concentrated population of stars. The night sky would look very different from the perspective of an inhabitant of a planet orbiting one of the stars in a globular cluster’s center: the sky would appear to be stuffed full of stars, in a stellar environment that is thousands of times more crowded than our own. Credit: European Space Agency | |
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| Jase1Posted at 2023-12-18 17:13:01(48Wks ago) Report Permalink URL | ||
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|  An enormous mosaic of Stephan’s Quintet is the largest image to date from NASA’s James Webb Space Telescope, covering about one-fifth of the Moon’s diameter. It contains over 150 million pixels and is constructed from almost 1,000 separate image files. The visual grouping of five galaxies was captured by Webb’s Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI). With its powerful, infrared vision and extremely high spatial resolution, Webb shows never-before-seen details in this galaxy group. Sparkling clusters of millions of young stars and starburst regions of fresh star birth grace the image. Sweeping tails of gas, dust and stars are being pulled from several of the galaxies due to gravitational interactions. Most dramatically, Webb’s MIRI instrument captures huge shock waves as one of the galaxies, NGC 7318B, smashes through the cluster. These regions surrounding the central pair of galaxies are shown in the colors red and gold. This composite NIRCam-MIRI image uses two of the three MIRI filters to best show and differentiate the hot dust and structure within the galaxy. MIRI sees a distinct difference in color between the dust in the galaxies versus the shock waves between the interacting galaxies. The image processing specialists at the Space Telescope Science Institute in Baltimore opted to highlight that difference by giving MIRI data the distinct yellow and orange colors, in contrast to the blue and white colors assigned to stars at NIRCam’s wavelengths. Together, the five galaxies of Stephan’s Quintet are also known as the Hickson Compact Group 92 (HCG 92). Although called a “quintet,” only four of the galaxies are truly close together and caught up in a cosmic dance. The fifth and leftmost galaxy, called NGC 7320, is well in the foreground compared with the other four. NGC 7320 resides 40 million light-years from Earth, while the other four galaxies (NGC 7317, NGC 7318A, NGC 7318B, and NGC 7319) are about 290 million light-years away. This is still fairly close in cosmic terms, compared with more distant galaxies billions of light-years away. Studying these relatively nearby galaxies helps scientists better understand structures seen in a much more distant universe. This proximity provides astronomers a ringside seat for witnessing the merging of and interactions between galaxies that are so crucial to all of galaxy evolution. Rarely do scientists see in so much exquisite detail how interacting galaxies trigger star formation in each other, and how the gas in these galaxies is being disturbed. Stephan’s Quintet is a fantastic “laboratory” for studying these processes fundamental to all galaxies. Tight groups like this may have been more common in the early universe when their superheated, infalling material may have fueled very energetic black holes called quasars. Even today, the topmost galaxy in the group – NGC 7319 – harbors an active galactic nucleus, a supermassive black hole that is actively accreting material. In NGC 7320, the leftmost and closest galaxy in the visual grouping, NIRCam was remarkably able to resolve individual stars and even the galaxy’s bright core. Old, dying stars that are producing dust clearly stand out as red points with NIRCam. The new information from Webb provides invaluable insights into how galactic interactions may have driven galaxy evolution in the early universe. NASA, ESA, CSA, STScI | |
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| Jase1Posted at 2023-12-19 13:44:10(48Wks ago) Report Permalink URL | ||
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|  On Aug. 18, 2023, the Mars Reconnaissance Orbiter (MRO) captured ridged lines carved onto Mars’ landscape by the gradual movement of ice. While surface ice deposits are mostly limited to Mars’ polar caps, these patterns appear in many non-polar Martian regions. As ice flows downhill, rock and soil are plucked from the surrounding landscape and ferried along the flowing ice surface and within the icy subsurface. While this process takes perhaps thousands of years or longer, it creates a network of linear patterns that reveal the history of ice flow. The MRO has been studying Mars since 2006. Its instruments zoom in for extreme close-up photography of the Martian surface, analyze minerals, look for subsurface water, trace how much dust and water are distributed in the atmosphere, and monitor daily global weather. These studies are identifying deposits of minerals that may have formed in water over long periods of time, looking for evidence of shorelines of ancient seas and lakes, and analyzing deposits placed in layers over time by flowing water. | |
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| SoupPosted at 2023-12-20 00:29:10(48Wks ago) Report Permalink URL | ||
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| Astrophysicists publish Kepler Giant Planet Search, an aid to 'figure out where to find life' by Deanna Csomo Ferrell, University of Notre Dame  Credit: Pixabay/CC0 Public Domain A team of astrophysicists led by Lauren Weiss, assistant professor in the Department of Physics and Astronomy at the University of Notre Dame, created the first-ever catalog of small, Earth-like planets with Jupiter-like siblings (planets that share the same star)—a critical component in the search for life elsewhere in our universe. Forthcoming in The Astrophysical Journal, the Kepler Giant Planet Search took a decade to complete. "This catalog is the first of its kind and an unprecedented opportunity to explore the diversity of planetary systems that are out there with things that are like the solar system, but not exactly the solar system, and it gives us a chance to rewrite the story of how the planets form," Weiss said. "The science question that I've been trying to answer over the past decade is: Of the other small planets like Earth that are out there, which of them have Jupiter siblings? Because this might be an important characteristic to look for, if we want to figure out where to find life." Previous research over the past several years has singled out Jupiter as one of the reasons for life on Earth. During the formation of the solar system, Jupiter slingshotted rocky and icy debris and embryonic planets toward Earth's current location. Jupiter still hurls debris in Earth's direction today. The debris may have carried water to our planet intact, creating the oceans and later, fostering life. Based on data collected from the W. M. Keck Observatory on Mauna Kea in Waimea, Hawaii, Weiss and collaborators recorded almost 3,000 radial velocities of 63 stars like our sun that host 157 known, small planets. The 157 small planets range from the size of Mars to the size of Neptune, and some of them have rocky surfaces that might be suitable for life. During the study, the team discovered 13 Jupiter-like planets, eight planets closer to the size of Neptune, and three companion stars. Perhaps counterintuitively, large, gas-filled giant planets outside of our solar system are difficult to find because some common detection methods don't work. The Kepler space telescope, which retired after nine years in 2018 after it ran out of fuel, had been an excellent tool for scientists to find small exoplanets that orbited close to their stars. It used the transit method, which measures tiny dips in the brightness of the companion star to indicate the presence of a planet as it orbits its star. Gas giants, however, are usually much farther from their stars and don't cross in front of them with any practical regularity for astronomers. Jupiter, for instance, takes 12 years to orbit the sun. Also, unlike planets close to their stars, distant planets often have slightly tilted orbits as seen from Earth, making the dips in brightness less prominent. Weiss and collaborators used the radial velocity method, which uses Doppler spectroscopy. The team measured the "wobble" of a star as the waves appear to pull slightly closer and away from Earth based on the gravitational tug from a large, orbiting planet. "Jupiters are large and they pull a lot on the stars we can measure. We can find them if we take many, many measurements over time, which is exactly what I had to do," Weiss said. For every star in the sample, she and collaborators observed the Doppler shift of the star's light waves for a minimum of 10 nights and in some cases up to hundreds of nights. "It varies depending on the star," she said, adding that "observing" the stars wasn't done by directly looking through the telescope. Astronomers control the Keck telescope from remote observing stations worldwide, including at Notre Dame. Though Weiss was excited about the discovery of the Jupiter-like planets, the catalog of Earth-and-Jupiter-like planetary systems is the aspect that will help astronomers in years to come. This paper, for instance, is the primary paper in the Kepler Giant Planet Search for which future papers will be based. Some will describe architectural patterns observed in planetary systems, the efficiency of detection of planets, and the joint occurrence of giant and small transiting planets. "Probably the thing I'm most excited about is revisiting this story of how the Earth formed," Weiss said. "Now that we have more information about what other kinds of planetary systems are out there, we're looking for patterns, finding new discoveries, and these possibilities really excite me." | |
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| Jase1Posted at 2023-12-20 18:34:50(48Wks ago) Report Permalink URL | ||
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|  This new image of NGC 2264, also known as the “Christmas Tree Cluster,” shows the shape of a cosmic tree with the glow of stellar lights. NGC 2264 is, in fact, a cluster of young stars — with ages between about one and five million years old — in our Milky Way about 2,500 light-years away from Earth. The stars in NGC 2264 are both smaller and larger than the Sun, ranging from some with less than a tenth the mass of the Sun to others containing about seven solar masses. This new composite image enhances the resemblance to a Christmas tree through choices of color and rotation. The blue and white lights (which blink in the animated version of this image) are young stars that give off X-rays detected by NASA’s Chandra X-ray Observatory. Optical data from the National Science Foundation’s WIYN 0.9-meter telescope on Kitt Peak shows gas in the nebula in green, corresponding to the “pine needles” of the tree, and infrared data from the Two Micron All Sky Survey shows foreground and background stars in white. This image has been rotated clockwise by about 160 degrees from the astronomer’s standard of North pointing upward, so that it appears like the top of the tree is toward the top of the image. Young stars, like those in NGC 2264, are volatile and undergo strong flares in X-rays and other types of variations seen in different types of light. The coordinated, blinking variations shown in this animation, however, are artificial, to emphasize the locations of the stars seen in X-rays and highlight the similarity of this object to a Christmas tree. In reality the variations of the stars are not synchronized. The variations observed by Chandra and other telescopes are caused by several different processes. Some of these are related to activity involving magnetic fields, including flares like those undergone by the Sun — but much more powerful — and hot spots and dark regions on the surfaces of the stars that go in and out of view as the stars rotate. There can also be changes in the thickness of gas obscuring the stars, and changes in the amount of material still falling onto the stars from disks of surrounding gas. | |
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| SoupPosted at 2023-12-20 23:27:43(48Wks ago) Report Permalink URL | ||
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| Fermi mission creates 14-year time-lapse of the gamma-ray sky by SLAC National Accelerator Laboratory  Credit: NASA The cosmos comes alive in an all-sky time-lapse movie made from 14 years of data acquired by NASA's Fermi Gamma-ray Space Telescope. Our sun, occasionally flaring into prominence, serenely traces a path through the sky against the backdrop of high-energy sources within our galaxy and beyond. "The bright, steady gamma-ray glow of the Milky Way is punctuated by intense, days-long flares of near-light-speed jets powered by supermassive black holes in the cores of distant galaxies," said Seth Digel, a senior staff scientist at SLAC National Accelerator Laboratory in Menlo Park, California, who created the images. "These dramatic eruptions, which can appear anywhere in the sky, occurred millions to billions of years ago, and their light is just reaching Fermi as we watch." Gamma rays are the highest-energy form of light. The movie shows the intensity of gamma rays with energies above 200 million electron volts detected by Fermi's Large Area Telescope (LAT) between August 2008 and August 2022. For comparison, visible light has energies between 2 and 3 electron volts. Brighter colors mark the locations of more intense gamma-ray sources. "One of the first things to strike your eye in the movie is a source that steadily arcs across the screen. That's our sun, whose apparent movement reflects Earth's yearly orbital motion around it," said Fermi Deputy Project Scientist Judy Racusin, who narrates a tour of the movie, at NASA's Goddard Space Flight Center in Greenbelt, Maryland. Most of the time, the LAT detects the sun faintly thanks to accelerated particles called cosmic rays—atomic nuclei traveling close to the speed of light. When they strike the sun's gas or even the light it emits, gamma rays result. At times, though, the sun suddenly brightens thanks to powerful eruptions called solar flares, which can briefly make our star one of the sky's brightest gamma-ray sources. The movie shows the sky in two different views. The rectangular view shows the entire sky with the center of our galaxy in the middle. This highlights the central plane of the Milky Way, which glows in gamma rays produced from cosmic rays striking interstellar gas and starlight. It's also flecked with many other sources, including neutron stars and supernova remnants. Above and below this central band, we're looking out of our galaxy and into the wider universe, peppered with bright, rapidly changing sources. Most of these are actually distant galaxies, and they're better seen in a different view centered on our galaxy's north and south poles. Each of these galaxies, called blazars, hosts a central black hole with a mass of a million or more suns. Somehow, the black holes produce extremely fast-moving jets of matter, and with blazars we're looking almost directly down one of these jets, a view that enhances their brightness and variability. "The variations tell us that something about these jets has changed," Racusin said. "We routinely watch these sources and alert other telescopes, in space and on the ground, when something interesting is going on. We have to be quick to catch these flares before they fade away, and the more observations we can collect, the better we'll be able to understand these events." Fermi plays a key role in the growing network of missions working together to capture these changes in the universe as they unfold. Many of these galaxies are extremely far away. For example, the light from a blazar known as 4C +21.35 has been traveling for 4.6 billion years, which means that a flare up we see today actually occurred as our sun and solar system were beginning to form. Other bright blazars are more than twice as distant, and together provide striking snapshots of black hole activity throughout cosmic time. Not seen in the time-lapse are many short-duration events that Fermi studies, such as gamma-ray bursts, the most powerful cosmic explosions. This is a result of processing data across several days to sharpen the images. The concept for the LAT was invented at SLAC, the instrument was assembled and tested at SLAC, which was also responsible for the electronics and flight software, and SLAC continues to process newly downlinked data several times per day. The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by Goddard. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States. | |
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| SoupPosted at 2023-12-27 00:51:56(47Wks ago) Report Permalink URL | ||
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| Astronomers detect new pulsar wind nebula and its associated pulsar by Tomasz Nowakowski  Composite image of the Galactic plane region and Potoroo, with the red layer showing the ASKAP total intensity image at 1368 MHz, and the green and blue layers representing WISE infrared images at 12 µm and 22 µm respectively. Known Galactic SNRs are indicated by red circles (Green, 2019, 2022), while known Galactic HII regions are marked by green circles (Anderson et al., 2014). The box highlights the section of deep interest. The inset is the ASKAP zoomed-in image showing Potoroo where a red cross marks the position of the X-ray source, while a red dashed line is Potoroo's axis of symmetry, which corresponds to the tail length studied in this paper. Credit: arXiv (2023). DOI: 10.48550/arxiv.2312.06961 Astronomers from the Western Sydney University in Australia and elsewhere report the detection of a new pulsar wind nebula and a pulsar that powers it. The discovery, presented in a paper published Dec. 12 on the pre-print server arXiv, was made using the Australian Square Kilometer Array Pathfinder (ASKAP), as well as MeerKAT and Parkes radio telescopes. Pulsar wind nebulae (PWNe) are nebulae powered by the wind of a pulsar. Pulsar wind is composed of charged particles; when it collides with the pulsar's surroundings, in particular with the slowly expanding supernova ejecta, it develops a PWN. Particles in PWNe lose their energy to radiation and become less energetic with distance from the central pulsar. Multiwavelength studies of these objects, including X-ray observations, especially using spatially-integrated spectra in the X-ray band, have the potential to uncover important information about particle flow in these nebulae. This could unveil important insights into the nature of PWNe in general. Now, a team of astronomers led by Western Sydney University's Sanja Lazarević has found a new pulsar wind nebula in radio-continuum surveys obtained from ASKAP and MeerKAT. They dubbed the new PWN "Potoroo," after a small marsupial native to Australia. Next, using the Parkes Ultra-Wideband Low (UWL) frequency receiver system, they detected the pulsar candidate, which received designation PSR J1638–4713. Further observations of PSR J1638–4713 confirmed that it powers the Potoroo. The observations show that Potoroo exhibits distinctive cometary morphology in both radio and X-ray band. This suggests that the pulsar leads the PWN and travels supersonically through the ambient medium. "For the pulsars that are propelled through the ambient medium at supersonic velocities, the resulting ram pressure transforms the PWN into a bow-shock. This process confines the pulsar wind in the opposite direction to that of the pulsar motion, forming a cometary-like shaped tail," the authors of the paper explained. According to the study, Potoroo is located at a distance of at least 32,500 light years, has a radio size of about 68.5 light years, while its X-ray size appears to be 10 times smaller. Therefore, Potoroo has the longest PWN radio trails known to date. The results indicate that Potoroo has an unusually steep overall radio spectrum—at a level of -1.27. This is below the typical values for the known PWNe. The astronomers suppose that such a steep overall spectral index may be due to the interaction of the parent supernova reverse shock with the PWN. When it comes to PSR J1638–4713, it has a spin period of 65.74 milliseconds and a dispersion measure of 1,553 pc/cm3—the second highest among all known radio pulsars. The observations found that PSR J1638–4713 is a young pulsar (with a characteristic age of 24,000 years), has a high spin-down luminosity, and a large projected velocity, exceeding 1,000 km/s. | |
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| SoupPosted at 2023-12-27 23:54:05(47Wks ago) Report Permalink URL | ||
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| Tatahouine: 'Star Wars meteorite' sheds light on the early solar system by Ben Rider-Stokes  The asteroid 4 vesta, left, and Tatooine, as seen in Star Wars, on the right. Credit: Nasa and wikipedia Locals watched in awe as a fireball exploded and hundreds of meteorite fragments rained down on the city of Tatahouine, Tunisia, on June 27, 1931. Fittingly, the city later became a major filming location for the Star Wars movie series. The desert climate and traditional villages became a huge inspiration to the director, George Lucas, who proceeded to name the fictional home planet of Luke Skywalker and Darth Vader, "Tatooine." The mysterious 1931 meteorite, a rare type of achondrite (a meteorite that has experienced melting) known as a diogenite, is obviously not a fragment of Skywalker's home planet. But it was similarly named after the city of Tatahouine. Now, a recent study has gleaned important insights into the the origin of the meteorite—and the early solar system. Lucas filmed various scenes for Star Wars in Tatahouine. These include Episode IV—A New Hope (1977), Star Wars: Episode I—The Phantom Menace (1999) and Star Wars: Episode 2—Attack of the Clones (2002). Various famous scenes were filmed there, including scenes of "Mos Espa" and "Mos Eisley Cantina." Mark Hamill, the actor who played Luke Skywalker, reminisced about filming in Tunisia and discussed it with Empire Magazine: "If you could get into your own mind, shut out the crew and look at the horizon, you really felt like you were transported to another world." Composition and origin Diogenites, named after the Greek philosopher Diogenes, are igneous meteorites (rocks that have solidified from lava or magma). They formed at depth within an asteroid and cooled slowly, resulting in the formation of relatively large crystals. Tatahouine is no exception, containing crystals as big as 5mm with black veins cutting cross the sample throughout. The black veins are called shock-induced impact melt veins, and are a result of high temperatures and pressures caused by a projectile smashing into the surface of the meteorite's parent body. The presence of these veins and the structure of the grains of pyroxene (minerals containing calcium, magnesium, iron, and aluminum) suggest the sample has experienced pressures of up to 25 gigapascals (GPa) of pressure. To put that into perspective, the pressure at the bottom of the Mariana Trench, the deepest part of our ocean, is only 0.1 GPa. So it is safe to say this sample has experienced a pretty hefty impact.  Seven of the diogenites analysed. Credit: F. Jourdan et al, CC BY-SA By evaluating the spectrum (light reflecting off their surface, broken down by wavelength) of meteorites and comparing it to asteroids and planets in our solar system, it has been suggested that diogenites, including Tatahouine, originate from the second largest asteroid in our asteroid belt, known as 4 Vesta. This asteroid possesses interesting and exciting information about the early solar system. Many of the meteorites from 4 Vesta are ancient, around ~4 billion years. Therefore, they offer a window to the past events of the early solar system that we are unable to evaluate here on Earth. Violent past The recent study investigated 18 diogenites, including Tatahouine, all from 4 Vesta. The authors undertook "radiometric argon-argon age dating" techniques to determine the ages of the meteorites. This is based on looking at two different isotopes (versions of elements whose nuclei have more or fewer particles called neutrons). We know that a certain argon isotope in samples increases with age at a known rate, helping scientists estimate the age of a sample by comparing the ratio between two different isotopes. The team also evaluated deformation caused by collisions, called impact events, using a type of electron microscope technique called electron backscatter diffraction. By combining the age dating techniques and the microscope technique, the authors managed to map the timing of impact events on 4 Vesta and the early solar system. The study suggests that 4 Vesta experienced ongoing impact events until 3.4 billion years ago when a catastrophic one occurred. This catastrophic event, possibly another colliding asteroid, resulted in multiple smaller rubble pile asteroids being produced known as "vestoids." Unraveling large-scale impact events such as this reveals the hostile nature of the early solar system. These smaller bodies experienced further collisions that caused material to hurtle to Earth over the last 50 to 60 million years—including the fireball in Tunisia. Ultimately, this work demonstrates the importance of investigating meteorites— impacts have played a major role in the evolution of asteroids in our solar system. | |
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| Jase1Posted at 2024-01-02 21:38:22(46Wks ago) Report Permalink URL | ||
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|  Not quite stars, not quite planets — brown dwarfs are objects that fall in between. Within the star cluster shown in this image, Webb observed the tiniest, free-floating brown dwarf ever discovered. Webb’s sharp infrared eye found this record-breaking brown dwarf in star cluster IC 348, which is about 1000 light-years away and only 5 million years old. Studying brown dwarfs helps us understand star formation as well as exoplanets, or planets beyond our solar system. Not only is there overlap between the smallest brown dwarfs and the largest exoplanets, free-floating brown dwarfs come with no stars attached — unlike exoplanets, which can be hidden in the glare of their host stars. But brown dwarfs aren’t the only free agents in space. Could this discovery be of an uncommon “rogue planet” instead? It’s unlikely: The surrounding stars are both young and low-mass, so they probably could not have produced and then ejected a giant planet in such a short time. We still don’t quite understand how brown dwarfs this small are even able to form. Webb's got more to do: Future surveys can search for similar objects to clarify their status, as well as the mysteries of their formation and composition. More: www.nasa.gov/missions/webb/nasas-webb-identifies-tiniest-... This image: This image from the NIRCam (Near-Infrared Camera) instrument on NASA’s James Webb Space Telescope shows the central portion of the star cluster IC 348. Astronomers combed the cluster in search of tiny, free-floating brown dwarfs: objects too small to be stars but larger than most planets. They found three brown dwarfs that are less than eight times the mass of Jupiter. The smallest weighs just three to four times Jupiter, challenging theories for star formation. The wispy curtains filling the image are interstellar material reflecting the light from the cluster’s stars – what is known as a reflection nebula. The material also includes carbon-containing molecules known as polycyclic aromatic hydrocarbons, or PAHs. The bright star closest to the center of the frame is actually a pair of type B stars in a binary system, which are the most massive stars in the cluster. Winds from these stars may help sculpt the large loop seen on the right side of the field of view. Image description: Wispy hair-like filaments of pink-purple fill the middle of the image, curving left and right on either side of the center. On the right, the filaments form a dramatic loop that seems to extend toward the viewer. At lower left are additional yellowsish filaments. Two prominent, bright stars near the center of the image show Webb’s eight-point diffraction spikes. Dozens of fainter stars are scattered across the image. | |
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| Alien4Posted at 2024-01-03 00:19:36(46Wks ago) Report Permalink URL | ||
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| Astrophysicists explore links between atmospheric oxygen and detecting extraterrestrial technology on distant planets by Lindsey Valich, University of Rochester  Air Supply: Coined by astrophysics Adam Frank and Amedeo Balbi, the "oxygen bottleneck" describes the critical threshold that separates worlds capable of fostering technological civilizations from those that fall short. "Without a ready source of fire, you're never going to develop higher technology," says Frank . Credit: University of Rochester illustration / Michael Osadciw In the quest to understand the potential for life beyond Earth, researchers are widening their search to encompass not only biological markers, but also technological ones. While astrobiologists have long recognized the importance of oxygen for life as we know it, oxygen could also be a key to unlocking advanced technology on a planetary scale. In a new perspective published in Nature Astronomy, Adam Frank, the Helen F. and Fred H. Gowen Professor of Physics and Astronomy at the University of Rochester and the author of The Little Book of Aliens (Harper, 2023), and Amedeo Balbi, an associate professor of astronomy and astrophysics at the University of Roma Tor Vergata, Italy, outline the links between atmospheric oxygen and the potential rise of advanced technology on distant planets. "We are ready to find signatures of life on alien worlds," Frank says. "But how do the conditions on a planet tell us about the possibilities for intelligent, technology-producing life?" "In our paper, we explore whether any atmospheric composition would be compatible with the presence of advanced technology," Balbi says. "We found that the atmospheric requirements may be quite stringent." Igniting cosmic technospheres Frank and Balbi posit that, beyond its necessity for respiration and metabolism in multicellular organisms, oxygen is crucial to developing fire—and fire is a hallmark of a technological civilization. They delve into the concept of "technospheres," expansive realms of advanced technology that emit telltale signs—called "technosignatures"—of extraterrestrial intelligence. On Earth, the development of technology demanded easy access to open-air combustion—the process at the heart of fire, in which something is burned by combining a fuel and an oxidant, usually oxygen. Whether it's cooking, forging metals for structures, crafting materials for homes, or harnessing energy through burning fuels, combustion has been the driving force behind industrial societies. Tracing back through Earth's history, the researchers found that the controlled use of fire and the subsequent metallurgical advancements were only possible when oxygen levels in the atmosphere reached or exceeded 18 percent. This means that only planets with significant oxygen concentrations will be capable of developing advanced technospheres, and, therefore, leaving detectable technosignatures. The oxygen bottleneck The levels of oxygen required to biologically sustain complex life and intelligence are not as high as the levels necessary for technology, so while a species might be able to emerge in a world without oxygen, it will not be able to become a technological species, according to the researchers. "You might be able to get biology—you might even be able to get intelligent creatures—in a world that doesn't have oxygen," Frank says, "but without a ready source of fire, you're never going to develop higher technology because higher technology requires fuel and melting." Enter the "oxygen bottleneck," a term coined by the researchers to describe the critical threshold that separates worlds capable of fostering technological civilizations from those that fall short. That is, oxygen levels are a bottleneck that impedes the emergence of advanced technology. "The presence of high degrees of oxygen in the atmosphere is like a bottleneck you have to get through in order to have a technological species," Frank says. "You can have everything else work out, but if you don't have oxygen in the atmosphere, you're not going to have a technological species." Targeting extraterrestrial hotspots The research, which addresses a previously unexplored facet in the cosmic pursuit of intelligent life, underscores the need to prioritize planets with high oxygen levels when searching for extraterrestrial technosignatures. "Targeting planets with high oxygen levels should be prioritized because the presence or absence of high oxygen levels in exoplanet atmospheres could be a major clue in finding potential technosignatures," Frank says. "The implications of discovering intelligent, technological life on another planet would be huge," adds Balbi. "Therefore, we need to be extremely cautious in interpreting possible detections. Our study suggests that we should be skeptical of potential technosignatures from a planet with insufficient atmospheric oxygen." | |
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| Alien4Posted at 2024-01-04 00:53:40(46Wks ago) Report Permalink URL | ||
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| Globular cluster VVV CL002 is falling down to the galactic center, study finds by Tomasz Nowakowski  Orbit computed for VVV CL002 (black line), overlaid on the probability densities of orbits projected on the galactic plane (left) and height above the plane z versus galactocentric radius (right). Lighter colors indicate more probable regions of space, that are more frequently sampled by the simulated orbits. Credit: arXiv (2023). DOI: 10.48550/arxiv.2312.16028 Using the Magellan Clay telescope in Chile, astronomers have performed high-resolution spectroscopic observations of a galactic globular cluster known as VVV CL002. They found that the cluster is falling down to the Milky Way's center. The discovery was reported in a research paper published December 26 on the pre-print server arXiv. Globular clusters (GCs) are collections of tightly bound stars orbiting galaxies. Astronomers perceive them as natural laboratories enabling studies on the evolution of stars and galaxies. In particular, globular clusters could help researchers to better understand the formation history and evolution of early-type galaxies, as the origin of GCs seems to be closely linked to periods of intense star formation. Located some 23,800 light years away, VVV CL002 is a relatively low-luminosity GC discovered in 2011 with the VISTA Variables in the Via Lactea (VVV) survey. With a galactocentric distance of approximately 1,300 light years, VVV CL002 is assumed to be closest GC to the center of the Milky Way. Recently, a team of astronomers led by Dante Minniti of the Andrés Bello Catholic University in Santiago, Chile, decided to conduct near-infrared high-resolution spectroscopy of VVV CL002 in order to find out how the cluster is surviving so close to the galactic center without being tidally disrupted. For this purpose, they employed the Warm INfrared Echelle spectrograph to Realize Extreme Dispersion and sensitivity (WINERED) at the Magellan Clay telescope. The observations found that VVV CL002 has a retrograde orbital configuration of relatively high eccentricity of 0.69, with perigalactocentric and apogalactocentric distances of 619 and 3,400 light years, respectively, well inside the bulge. It turned out that the orbit of VVV CL002 is tighter than the orbits of all other known GCs. The study delivered important insights into the chemical composition of VVV CL002. It was found that the cluster has a metallicity at a level of -0.54 and showcases high alpha-element abundance. This indicates that VVV CL002 is an old GC that formed together with other clusters. Therefore, according to the authors of the paper, VVV CL002 was formed outside the central region of the Milky Way but is now falling down to the galactic center. "This brings us to a scenario where VVV CL002 was formed at a relatively large stellar birth radius and started to fall towards the center recently. It is probably doomed to continue spiraling into the inner parsecs and be destroyed in the not-so-distant future," the researchers explained. The astronomers underlined that further high-resolution observations of VVV CL002 could be essential in order to better understand the survival and migration mechanisms of galactic globular clusters. | |
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| Jase1Posted at 2024-01-06 13:33:06(46Wks ago) Report Permalink URL | ||
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|  TYPE: Emission and Reflection Nebula CONSTELLATION: Orion DISTANCE: 1,344 light-years MAGNITUDE: 4.0 The Great Orion Nebula is one of the best and easiest objects to locate. To find it, you only need to look beneath the three stars that form Orion’s belt. Even under suburban skies, you’ll see it as a tiny, misty patch, while binoculars will reveal it to be slightly misshapen, with a bright, off-center core. A small scope at low power will show the nebula as a smooth, smokey cloud with a slightly greenish tint. Some texturing may be visible on the southern edge, along with a dark patch that goes by the name of The Fish’s Mouth. You’ll also see a tight group of three or four bright stars, known as the Trapezium. These are young stars - just 300,000 years old - born from the nebula itself. | |
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| Alien4Posted at 2024-01-08 19:12:52(45Wks ago) Report Permalink URL | ||
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| Astronomers observe three iron rings in a planet-forming disk by Max Planck Society  Observations with the European Southern Observatory's (ESO) Very Large Telescope Interferometer (VLTI) found various silicate compounds and potentially iron, substances we also find in large amounts in the solar system's rocky planets. Credit: Jenry The origin of Earth and the solar system inspires scientists and the public alike. By studying the present state of our home planet and other objects in the solar system, researchers have developed a detailed picture of the conditions when they evolved from a disk made of dust and gas surrounding the infant sun some 4.5 billion years ago. With the breathtaking progress made in star and planet formation research aiming at far-away celestial objects, we can now investigate the conditions in environments around young stars and compare them to the ones derived for the early solar system. Using the European Southern Observatory's (ESO) Very Large Telescope Interferometer (VLTI), an international team of researchers led by József Varga from the Konkoly Observatory in Budapest, Hungary, did just that. They observed the planet-forming disk of the young star HD 144432, approximately 500 light-years away. "When studying the dust distribution in the disk's innermost region, we detected for the first time a complex structure in which dust piles up in three concentric rings in such an environment," says Roy van Boekel. He is a scientist at the Max Planck Institute for Astronomy (MPIA) in Heidelberg, Germany, and a co-author of the underlying research article to appear in the journal Astronomy & Astrophysics. "That region corresponds to the zone where the rocky planets formed in the solar system," van Boekel adds. Compared to the solar system, the first ring around HD 144432 lies within Mercury's orbit, and the second is close to Mars's trajectory. Moreover, the third ring roughly corresponds to Jupiter's orbit. Up to now, astronomers have found such configurations predominantly on larger scales corresponding to the realms beyond where Saturn circles the sun. Ring systems in the disks around young stars generally point to planets forming within the gaps as they accumulate dust and gas on their way. However, HD 144432 is the first example of such a complex ring system so close to its host star. It occurs in a zone rich in dust, the building block of rocky planets like Earth. Assuming the rings indicate the presence of two planets forming within the gaps, the astronomers estimated their masses to resemble roughly that of Jupiter. Conditions may be similar to the early solar system The astronomers determined the dust composition across the disk up to a separation from the central star that corresponds to the distance of Jupiter from the sun. What they found is very familiar to scientists studying Earth and the rocky planets in the solar system: various silicates (metal-silicon-oxygen compounds) and other minerals present in Earth's crust and mantle, and possibly metallic iron as is present in Mercury's and Earth's cores. If confirmed, this study would be the first to have discovered iron in a planet-forming disk. "Astronomers have thus far explained the observations of dusty disks with a mixture of carbon and silicate dust, materials that we see almost everywhere in the universe," van Boekel explains. However, from a chemical perspective, an iron and silicate mixture is more plausible for the hot, inner disk regions. Indeed, the chemical model that Varga, the main author of the underlying research article, applied to the data yields better-fitting results when introducing iron instead of carbon. Furthermore, the dust observed in the HD 144432 disk can be as hot as 1800 Kelvin (approx. 1500 degrees Celsius) at the inner edge and as moderate as 300 Kelvin (approx. 25 degrees Celsius) farther out. Minerals and iron melt and recondense, often as crystals, in the hot regions near the star. In turn, carbon grains would not survive the heat and instead be present as carbon monoxide or carbon dioxide gas. However, carbon may still be a significant constituent of the solid particles in the cold outer disk, which the observations carried out for this study cannot trace. Iron-rich and carbon-poor dust would also fit nicely with the conditions in the solar system. Mercury and Earth are iron-rich planets, while the Earth contains relatively little carbon. "We think that the HD 144432 disk may be very similar to the early solar system that provided lots of iron to the rocky planets we know today," says van Boekel. "Our study may pose as another example showing that the composition of our solar system may be quite typical." Interferometry resolves tiny details Retrieving the results was only possible with exceptionally high-resolution observations, as provided by the VLTI. By combining the four VLT 8.2-meter telescopes at ESO's Paranal Observatory, they can resolve details as if astronomers would employ a telescope with a primary mirror of 200 meters in diameter. Varga, van Boekel and their collaborators obtained data using three instruments to achieve a broad wavelength coverage ranging from 1.6 to 13 micrometers, representing infrared light. MPIA provided vital technological elements to two devices, GRAVITY and the Multi AperTure mid-Infrared SpectroScopic Experiment (MATISSE). One of MATISSE's primary purposes is to investigate the rocky planet-forming zones of disks around young stars. "By looking at the inner regions of protoplanetary disks around stars, we aim to explore the origin of the various minerals contained in the disk—minerals that later will form the solid components of planets like the Earth," says Thomas Henning, MPIA director and co-PI of the MATISSE instrument. However, producing images with an interferometer like the ones we are used to obtaining from single telescopes is not straightforward and very time-consuming. A more efficient use of precious observing time to decipher the object structure is to compare the sparse data to models of potential target configurations. In the case of the HD 144432 disk, a three-ringed structure represents the data best. How common are structured, iron-rich planet-forming disks? Besides the solar system, HD 144432 appears to provide another example of planets forming in an iron-rich environment. However, the astronomers will not stop there. "We still have a few promising candidates waiting for the VLTI to take a closer look at," van Boekel points out. In earlier observations, the team discovered a number of disks around young stars that indicate configurations worth revisiting. However, they will reveal their detailed structure and chemistry using the latest VLTI instrumentation. Eventually, astronomers may be able to clarify whether planets commonly form in iron-rich dusty disks close to their parent stars. | |
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| Alien4Posted at 2024-01-08 23:14:05(45Wks ago) Report Permalink URL | ||
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| Scientists flip around gravitational-wave data analysis: Have LIGO and Virgo detected a merger of dark-matter stars? by Galician Institute of High Energy Physics  Gravitational waves are ripples in the fabric of spacetime that travel at the speed of light. These are produced in some of the most violent events in the universe, such as black-hole mergers, supernovae, or the Big Bang itself. Since their first detection in 2015, and after three observing runs, the Advanced LIGO and Virgo detectors have detected around 100 such waves. Thanks to these observations, we are starting to unveil the black-hole population of our universe, study gravity in its most extreme regime and even determine the formation of elements like gold or platinum during the merger of neutron stars. The LIGO and Virgo detectors are nothing but the most precise rulers ever built by humankind, able to measure the subtle squeezing and stretching of spacetime produced by gravitational waves. The detection of the waves and determination of their sources, relies on the comparison of the detector data to theoretical models, or "templates," for the waves emitted by each type of source. This is in essence the way the famous Shazam app tells us the details (name, author, year.) of the music being played in a bar. While there are several ways to compute gravitational-wave templates, the most accurate one (and sometimes the only one) is through extremely accurate numerical simulations performed on some of the most powerful supercomputers in the world. There is, however, a caveat: most numerical simulations do not output the quantity that the detectors read, known as strain, but its second-time derivative, known as the Newman-Penrose scalar. This makes scientists need to perform two-time integrals on the result of their simulations. Dr. Isaac Wong, co-lead of the study from the Chinese University of Hong Kong, explains, "While taking integrals may sound simple, this operation is subject to well-known errors that we can only handle for rather simple sources like the merger of black holes in circular orbits that LIGO and Virgo have been detecting so far. Moreover, doing this is not straightforward, requiring quite some hand tuning that involves human choices." In recent work published in the journal Physical Review X, a team led by Dr. Juan Calderón Bustillo "La Caixa Junior Leader" and "Marie Curie Fellow" at the Galician Institute of High Energy Physics (Spain) and Dr. Isaac Wong, from the Chinese University of Hong Kong, have proposed to flip around the way gravitational-wave analyses have been performed since its birth. Rather than taking integrals on their simulations, the authors propose taking derivatives on the detector data, while leaving their simulations untouched.  Recreation of a boson star merger. Credit: Nicolas Sanchis Gual and Rocio Garcia Souto. Dr. Calderón-Bustillo explains, "While this may look like quite a trivial tweak, it comes with great advantages. First, this greatly simplifies the process of obtaining templates that can be compared to LIGO-Virgo data. Most importantly, we can now do this safely for any source that supercomputers can simulate." In fact, the team has long been interested in studying the possibility that some of the current signals may be due to something way more exotic and mysterious, known as boson stars. Dr. Sanchis-Gual, co-author of the study from the University of Valencia says, "Boson stars behave very much like black holes, but they are fundamentally different, as they lack the two most distinctive (and somewhat problematic) aspects of black holes: their no-return surface known as event horizon, and the singularity in the interior, where laws of physics break down." While the team knew how to simulate these sources in supercomputers, "we were having real trouble understanding how to transform the output of our simulations into something we could compare with the detector data, due to well-known issues. The idea of taking derivatives from the data, made things extremely simple," says Prof. Alejandro Torres, also from the University of Valencia. As a first application of their new technique, in a separate work published in Physical Review D, the team compared some gravitational-wave events observed by LIGO and Virgo to a large catalog of simulations for boson-star mergers. "If existing, boson star mergers exist, these could account for at least part of what we know as dark matter," says Prof. Carlos Herdeiro, from the University of Aveiro. In fact, the team found that one of the most mysterious events observed to date, known as GW190521, is indeed consistent with such simulations. This reinforces a similar result obtained by the team in 2020, obtained using a significantly smaller catalog. Samson Leong, Ph.D student from the Chinese University of Hong Kong, involved in both studies says, "It's very exciting to see that GW190521 is consistent with a boson-star merger. This does not underscore the potential role of these exotic objects in the future of gravitational wave astronomy." Prof. Tjonnie Li, from K.U. Leuven adds, "This result also demonstrates the power of our new approach. By simply taking derivatives, we've opened a broader window for exploring and understanding the cosmos through gravitational waves." | |
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| Jase1Posted at 2024-01-09 15:06:56(45Wks ago) Report Permalink URL | ||
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|  This image from the NASA/ESA Hubble Space Telescope features a richness of spiral galaxies: the large, prominent spiral galaxy on the right side of the image is NGC 1356; the two apparently smaller spiral galaxies flanking it are LEDA 467699 (above it) and LEDA 95415 (very close at its left) respectively; and finally, IC 1947 sits along the left side of the image. This image is a really interesting example of how challenging it can be to tell whether two galaxies are actually close together, or just seem to be from our perspective here on Earth. A quick glance at this image would likely lead you to think that NGC 1356, LEDA 467699, and LEDA 95415 were all close companions, while IC 1947 was more remote. However, we have to remember that two-dimensional images such as this one only give an indication of angular separation: that is, how objects are spread across the sphere of the night sky. What they cannot represent is the distance objects are from Earth. For instance, while NGC 1356 and LEDA 95415 appear to be so close that they must surely be interacting, the former is about 550 million light-years from Earth and the latter is roughly 840 million light-years away, so there is nearly a whopping 300 million light-year separation between them. That also means that LEDA 95415 is likely nowhere near as much smaller than NGC 1356 as it appears to be. On the other hand, while NGC 1356 and IC 1947 seem to be separated by a relative gulf in this image, IC 1947 is only about 500 million light-years from Earth. The angular distance apparent between them in this image only works out to less than 400,000 light-years, so they are actually much closer neighbors in three-dimensional space than NGC 1356 and LEDA 95415! | |
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| SoupPosted at 2024-01-09 22:15:33(45Wks ago) Report Permalink URL | ||
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| 'Blob-like' home of farthest-known fast radio burst is collection of seven galaxies, researchers find by Northwestern University  A Hubble Space Telescope image of the host galaxy of an exceptionally powerful fast radio burst, FRB 20220610A. Hubble's sensitivity and sharpness reveals a compact group of multiple galaxies that may be in the process of merging. They existed when the universe was only 5 billion years old. FRB 20220610A was first detected on June 10, 2022, by the Australian Square Kilometer Array Pathfinder (ASKAP) radio telescope in Western Australia. The European Southern Observatory's Very Large Telescope in Chile confirmed that the FRB came from a distant place. Credit: NASA, ESA, STScI, Alexa Gordon (Northwestern) In summer 2022, astronomers detected the most powerful fast radio burst (FRB) ever observed. And coming from a location that dates halfway back to the Big Bang, it also was the farthest known FRB spotted to date. Now, astronomers led by Northwestern University have pinpointed the extraordinary object's birthplace—and it's rather curious, indeed. Using images from NASA's Hubble Space Telescope, the researchers traced the FRB back to not one galaxy but a group of at least seven galaxies. The galaxies in the collection appear to be interacting with one another—perhaps even on the path to a potential merger. Such groups of galaxies are rare and possibly led to conditions that triggered the FRB. The unexpected finding might challenge scientific models of how FRBs are produced and what produces them. "Without the Hubble's imaging, it would still remain a mystery as to whether this FRB originated from one monolithic galaxy or from some type of interacting system," said Northwestern's Alexa Gordon, who led the study. "It's these types of environments—these weird ones—that drive us toward a better understanding of the mystery of FRBs." Gordon presents this research during the 243rd meeting of the American Astronomical Society held 7–11 January, in New Orleans, Louisiana. A corresponding paper is also published on the arXiv preprint server. Gordon is a graduate student in astronomy at Northwestern's Weinberg College of Arts and Sciences, where she is advised by study co-author Wen-fai Fong, an associate professor of physics and astronomy. Fong and Gordon also are members of the Center for Interdisciplinary Exploration and Research in Astrophysics(CIERA). Birth from a blob? Flaring up and disappearing within milliseconds, FRBs are brief, powerful radio blasts that generate more energy in one quick burst than our sun emits in an entire year. And the record-breaking FRB (dubbed FRB 20220610A) was even more extreme than its predecessors. Not only was it four times more energetic than closer FRBs, it also clocked in as the most distant FRB yet discovered. When FRB 20220610A originated, the universe was just 5 billion years old. (For comparison, the universe is now 13.8 billion years old.) In early observations, the burst appeared to have originated near an unidentifiable, amorphous blob, which astronomers initially thought was either a single, irregular galaxy or a group of three distant galaxies. But, in a new twist, the Hubble's sharp images now suggest the blob might be as least as many as seven galaxies in incredibly close proximity to one another. In fact, the galaxies are so close to one another that they could all fit inside our own Milky Way.  "There are some signs that the group members are 'interacting,'" Fong said. "In other words, they could be trading materials or possibly on a path to merging. These groups of galaxies (called compact groups) are incredibly rare environments in the universe and are the densest galaxy-scale structures we know of." "This interaction could trigger bursts of star formation," Gordon said. "That might indicate that the progenitor of FRB 20220610A is associated with a fairly recent population of stars which matches what we've learned from other FRBs." "Despite hundreds of FRB events discovered to date, only a fraction of those have been pinpointed to their host galaxies," said study co-author Yuxin (Vic) Dong, an NSF Graduate Research, astronomy Ph.D. student in Fong's lab and member of CIERA. "Within that small fraction, only a few came from a dense galactic environment, but none have ever been seen in such a compact group. So, its birthplace is truly rare." Enigmatic explosions Although astronomers have uncovered up to 1,000 FRBs since first discovering them in 2007, the sources behind the blinding flashes remain stubbornly uncertain. While astronomers have yet to reach a consensus on the possible mechanisms behind FRBs, they generally agree that FRBs must involve a compact object, such as a black hole or neutron star. By revealing the true nature of FRBs, astronomers not only could learn about the mysterious phenomena but also about the true nature of the universe itself. When radio waves from FRBs finally meet our telescopes, they have traveled for billions of years from the distant, early universe. During this cross-universe odyssey, they interact with material along the way. "Radio waves, in particular, are sensitive to any intervening material along the line of sight—from the FRB location to us," Fong said. "That means the waves have to travel through any cloud of material around the FRB site, through its host galaxy, across the universe and finally through the Milky Way. From a time delay in the FRB signal itself, we can measure the sum of all of these contributions." To continue to probe FRBs and their origins, astronomers need to detect and study more of them. And with technology continually becoming more sensitive, Gordon says more detections—potentially even capturing incredibly faint FRBs—are right around the corner. "With a larger sample of distant FRBs, we can begin to study the evolution of FRBs and their host properties by connecting them to more nearby ones and perhaps even start to identify more strange populations," Dong said. "In the near future, FRB experiments will increase their sensitivity, leading to an unprecedented rate in the number of FRBs detected at these distances," Gordon said. "Astronomers will soon learn just how special the environment of this FRB was." The study is titled "A fast radio burst in a compact galaxy group at z ~ 1." Astronomers first detected FRB 20220610A with the Australian Square Kilometer Array Pathfinder radio telescope in Western Australia and then confirmed its origin with the European Southern Observatory's Very Large Telescope in Chile. | |
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