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 Post subject: Storm-Driven Ocean Swells Trigger Catastrophic Disintegratio
PostPosted: Thu Feb 25, 2021 10:59 pm 
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Storm-Driven Ocean Swells Trigger Catastrophic Disintegration of Antarctic Ice Shelves

 

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Global sea-level rise up close, at its source: in only a matter of days, the collapse of the Larsen B Ice Shelf in 2002 removed an area of ice shelf that had been in place for the previous 11,500 years. Removal of the ice shelf buttressing effect also caused a 3- to 8-fold increase in the discharge of glacial ice, behind the shelf, into the ocean, in the year following disintegration.


Storm-driven ocean swells have triggered the catastrophic disintegration of Antarctic ice shelves in recent decades, according to new research published in Aspect today. Dr Rob Massom, of the Australian Antarctic Category and the Antarctic Climate and Ecosystems Cooperative Research Centre, said that reduced sea ice coverage since the late 1980s led to increased exposure of ice shelves on the Antarctic Peninsula to ocean swells, causing them to flex and cease.

 


"Sea ice acts as a protective buffer to ice shelves, by dampening destructive ocean swells before they reach the ice shelf edge," proceed author Massom said. "But where there is loss of sea ice, storm-generated ocean swells can easily reach the exposed ice shelf, causing the first few kilometres of its outer margin to flex. Over time, this flexing enlarges pre-existing fractures until long lean sliver icebergs cease away or calve from the shelf front. This is like the straw that broke the camels back, triggering the runaway collapse of large areas of ice shelves weakened by pre-existing fracturing and decades of surface flooding."


Study co-author Dr Luke Bennetts, from the University of Adelaides School of Mathematical Sciences, said the finding highlights the need for sea ice and ocean waves to be included in ice sheet modelling.


This will allow scientists to more accurately forecast the fate of the remaining ice shelves and better predict the contribution of Antarcticas ice sheet to sea level rise, as climate changes.


 


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"The contribution of the Antarctic Ice Sheet is currently the greatest source of uncertainty in projections of global mean sea level rise," Bennetts said. Ice shelves fringe about three quarters of the Antarctic coast and they play a crucially important role in moderating sea level rise by buttressing and slowing the movement of glacial ice from the interior of the continent to the ocean. While ice shelf disintegration doesnt directly raise sea level because they are already floating, the resulting acceleration of the tributary glaciers behind the ice shelf, into the Southern Ocean, does."


Study co-author, Dr Phil Reid, from the Australian Bureau of Meteorology, said the research identifies a previously under-appreciated link between sea ice loss and ice shelf stability. "Our study underlines the importance of understanding the mechanisms driving these sea ice trends, particularly in regions where sea ice acts as a protective buffer against ocean processes," he said.


The discovery comes after the international research team, from Australia, the United States and New Zealand, combined satellite images and surface and ocean wave data with modelling, to analyse five major ice shelf disintegrations, between 1995 and 2009.


These included the hasty and rapid losses of 1600 square kilometres of ice from the Larsen A Ice Shelf in 1995, 3320 square kilometers from the Larsen B Ice Shelf in 2002, and 1450 square kilometers from the Wilkins Ice Shelf in 2009.


Each disintegration event occurred during periods when sea ice was significantly reduced or absent, and when ocean waves were large.


The Daily Galaxy via University of Adelaide


 


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 Post subject: "Virtual Twin" of a Previously Known Alien Planet
PostPosted: Mon Mar 08, 2021 9:21 am 
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"Virtual Twin" of a Previously Known Alien Planet Observed



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"We have found a gas-giant planet that is a virtual twin of a previously known planet, but it looks like the two objects formed in different ways," said Trent Dupuy, astronomer at the Gemini Obervatory.


Proceed Wircam image of 2MASS 0249 system taken wiht CFHTs infrared camera WIRCam. 2MASS 0249c is located 2000 astronomical units from the host brown dwarfs that are unresolved in this image. Credit: T. Dupuy, M. Liu

 


When it comes to extrasolar planets, appearances can be deceiving. Astronomers have imaged a new planet, and it appears nearly identical to one of the best studied gas-giant planets. But this doppelgnger differs in one very important way: its origin.


Emerging from stellar nurseries of gas and dust, stars are born like kittens in a litter, in bunches and inevitably wandering away from their birthplace. These litters comprise stars that vary greatly, ranging from tiny runts incapable of generating their own energy (called brown dwarfs) to massive stars that end their lives with supernova explosions.


In the midst of this turmoil, planets form around these new stars. And once the stellar nursery exhausts its gas, the stars (with their planets) abandon their birthplace and freely wander the Galaxy. Because of this exodus, astronomers believe there should be planets born at the same time from the same stellar nursery, but orbiting stars that have moved far away from each other over the eons, like long-lost siblings.


"To date, exoplanets found by proceed imaging have basically been individuals, each distinct from the other in their appearance and age. Finding two exoplanets with almost identical appearances and yet having formed so differently opens a new window for understanding these objects," said Michael Liu, astronomer at the University of Hawaii Institute for Astronomy, and a collaborator on this toil.


Dupuy, Liu, and their collaborators have identified the first case of such a planetary doppelgnger. One object has long been known: the 13-Jupiter-mass planet beta Pictoris b, one of the first planets discovered by proceed imaging, back in 2009. The new object, dubbed 2MASS 0249 c, has the same mass, brightness, and spectrum as beta Pictoris b.


After discovering this object with the Canada-France-Hawaii Telescope (CFHT), Dupuy and collaborators then determined that 2MASS 0249 c and beta Pictoris b were born in the same stellar nursery. On the surface, this makes the two objects not just look-alikes but real siblings.


The infrared spectra of 2MASS 0249c and beta Pictoris b are similar, as expected for two objects of comparable mass that formed in the same stellar nursery. Unlike 2MASS 0249c, beta Pictoris b orbits much closer to its massive host star and is imbedded in a bright circumstellar disk. Credit: T. Dupuy, ESO/A.-M. Lagrange et al


However, the planets have vastly different living situations, namely the types of stars they orbit. The host for beta Pictoris b is a star 10 times brighter than the Sun, while 2MASS 0249 c orbits a pair of brown dwarfs that are 2000 times fainter than the Sun. Furthermore, beta Pictoris b is relatively close to its host, about 9 astronomical units (AU, the distance from the Earth to the Sun), while 2MASS 0249 c is 2000 AU from its binary host.



These drastically different arrangements suggest that the planets upbringings were not at all alike. The traditional picture of gas-giant formation, where planets start as small rocky cores around their host star and grow by accumulating gas from the stars disk, likely created beta Pictoris b. In contrast, the host of 2MASS 0249 c did not have enough of a disk to make a gas giant, so the planet likely formed by directly accumulating gas from the original stellar nursery.


"2MASS 0249 c and beta Pictoris b show us that aspect has more than one way to make very similar looking exoplanets," says Kaitlin Kratter, astronomer at the University of Arizona and a collaborator on this toil. "beta Pictoris b probably formed like we think most gas giants do, starting from tiny dust grains. In contrast, 2MASS 0249 c looks like an underweight brown dwarf that formed from the collapse of a gas cloud. Theyre both considered exoplanets, but 2MASS 0249 c illustrates that such a simple category can obscure a complicated reality."


The team first identified 2MASS 0249 c using images from CFHT, and their repeated observations revealed this object is orbiting at a large distance from its host. The system belongs to the beta Pictoris moving group, a widely dispersed set of stars named for its famous planet-hosting star. The teams observations with the W. M. Keck Telescope determined that the host is actually a closely separated pair of brown dwarfs. So altogether, the 2MASS 0249 system comprises two brown dwarfs and one gas-giant planet. Follow-up spectroscopy of 2MASS 0249 c with the NASA Infrared Telescope Facility and the Astrophysical Research Consortium 3.5-meter Telescope at Apache Point Telescope demonstrated that it shares a remarkable resemblance to beta Pictoris b.


The 2MASS 0249 system is an appealing target for future studies. Most directly imaged planets are very close to their host stars, inhibiting detailed studies of the planets due to the bright light from the stars. In contrast, the very wide separation of 2MASS 0249 c from its host binary will make measurements of properties like its surface weather and composition much easier, leading to a better understanding of the characteristics and origins of gas-giant planets.


The Daily Galaxy via Canada-France-Hawaii Telescope


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 Post subject: "Ancient Scars" --Our Planets Telltale Traces of C
PostPosted: Tue Mar 09, 2021 10:45 pm 
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"Ancient Scars" --Our Planets Telltale Traces of Collisions With Dark Matter

 




Dark-Matter-Web






Minerals deep inside Earth might contain telltale traces of collisions with dark matter the elusive stuff that researchers think makes up most of the matter in the Universe. Experiments designed to search for these traces could one day complement or even compete with ongoing efforts to detect dark matter directly.


Researchers using sophisticated detectors sunk deep underground have searched for signs of dark matter for decades continues Anil Ananthaswamy in the journal Aspect. But now, Katherine Freese, a physicist at the University of Michigan in Ann Arbor, and her colleagues suggest that minerals such as halite (sodium chloride) and zabuyelite (lithium carbonate), can act as ready-made detectors.

Astronomers can detect the gravitational influence of dark matter on the motion of galaxies and galactic clusters, but have never been capable to spot it directly. The prevailing explanation for dark matter is that its made of material known as weakly interacting massive particles (WIMPs), which interact with normal matter mainly through gravity.


Proceed-detection experiments extent to find the faint after-effects of WIMPs colliding with the nuclei of atoms in materials such as germanium, silicon or sodium iodide inside a detector.


Such experiments must be positioned deep underground, to guard against the cosmic rays that bombard Earths surface. These rays can also abandon faint traces of their collisions with detector materials, which can swamp any potential signals from dark matter. So far, only one experiment the DAMA/LIBRA experiment at the Gran Sasso National Laboratory in Italy says it has detected dark matter, but the claim remains unverified.


Freese and her colleagues argue that minerals such as halite and zabuyelite are already deep inside Earth and thus are shielded from cosmic rays. According to the teams analysis, published perpetuate month on the preprint server arXiv, if a WIMP were to smash into the nucleus of an atom of, say, sodium or chlorine, the nucleus would recoil. This would etch a path anywhere from 1 to 1,000 nanometres long in the mineral.


An experiment could extract the minerals which can be around 500 million years old from kilometres-deep boreholes that already exist for geological research and oil prospecting. Physicists would need to crack open the extracted minerals and scan the exposed surfaces under an electron or atomic force microscope for the tracks made by recoiling nuclei. They could also use X-ray or ultraviolet 3D scanners to study bigger chunks of minerals faster, but with lower resolution.


Potential collisions with WIMPs will create different signatures in each element of any mineral and thus provide different sources of information. For example, sodium chloride consists of both sodium and chlorine, so you get multiple signals from just one mineral, says Freese. If you do find some positive signals, then you can figure out what kind of WIMP it is based on its scattering off of sodium and its scattering off of chlorine.


The idea is pretty exciting, says Dan Hooper, a physicist at the Fermi National Accelerator Laboratory in Batavia, Illinois. Although there are many details yet to be demonstrated before this kind of program could be realistically implemented, I dont see any excuse why it couldnt succeed, at least in principle.


But others, such as physicist Juan Collar of the University of Chicago in Illinois, strike a more cautionary note. In the mid-1990s, physicists considered using the mineral mica as a target for similar searches for dark matter2. But Collar subsequently showed3 that radioactivity from uranium in the minerals would create tracks in the mica that would be impossible to distinguish from those created by WIMPs. He fears a similar fate would befall Freeses proposal.


This issue is not limited to mica, but instead affects any mineral containing the ubiquitous natural abundance of uranium and thorium, he says. They may be capable to find minerals where this problem is reduced, but I think that right now their claims are way too optimistic.


Freese acknowledges that uranium is a concern, although its unclear whether the minerals that she and her team propose contain uranium or thorium contaminants. But she adds that it might be possible to identify obvious etching patterns that can be created only by a burst of radioactivity, and to circumvent them. The truth is you have to do it and find out, she says.


The Daily Galaxy via Nature 


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 Post subject: Todays "Planet Earth Report" --Relic Billion-Year-
PostPosted: Thu Mar 11, 2021 2:58 pm 
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Todays "Planet Earth Report" --Relic Billion-Year-Old Lake Unveils Clues to Alien Life

 


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"For most of Earth history our planet was populated with microbes, and projecting into the future they will likely be the stewards of the planet long after we are gone," says Crockford, now a postdoctoral researcher at Princeton University and Israels Weizmann Institute of Science. "Understanding the environments they shape not only informs us of our own past and how we got here, but also provides clues to what we might find if we discover an inhabited exoplanet."


A sample of ancient oxygen, teased out of a 1.4 billion-year-old evaporative lake deposit in Ontario, provides fresh evidence of what the Earths atmosphere and biosphere were like during the interval leading up to the emergence of animal life.

 


The findings, published in the journal Aspect, represent the oldest measurement of atmospheric oxygen isotopes by nearly a billion years. The results support previous research suggesting that oxygen levels in the air during this time in Earth history were a tiny fraction of what they are today due to a much less productive biosphere.


"It has been suggested for many decades now that the composition of the atmosphere has significantly varied through time," says Peter Crockford, who led the study as a PhD student at McGill University. "We provide unambiguous evidence that it was indeed much different 1.4 billion years ago."


The study provides the oldest gauge yet of what earth scientists mention as "primary production," in which micro-organisms at the base of the food chain - algae, cyanobacteria, and the like - produce organic matter from carbon dioxide and pour oxygen into the air.


"This study shows that primary production 1.4 billion years ago was much less than today," says senior co-author Boswell Wing, who helped supervise Crockfords toil at McGill. "This means that the size of the global biosphere had to be smaller, and likely just didnt yield enough food - organic carbon - to support a lot of complex macroscopic life," says Wing, now an associate professor of geological sciences at University of Colorado at Boulder.


To come up with these findings, Crockford teamed up with colleagues from Yale University, University of California Riverside, and Lakehead University in Thunder Bay, Ontario, who had collected pristine samples of ancient salts, known as sulfates, found in a sedimentary rock formation north of Lake Superior. Crockford shuttled the samples to Louisiana State University, where he worked closely with co-authors Huiming Bao, Justin Hayles, and Yongbo Peng, whose lab is one of a handful in the world using a specialized mass-spectrometry technique capable of probing such materials for rare oxygen isotopes within sulfates.


The toil also sheds new light on a stretch of Earths history known as the "boring billion" because it yielded little apparent biological or environmental change.


"Subdued primary productivity during the mid-Proterozoic era - roughly 2 billion to 800 million years ago - has long been implied, but no coarse data had been generated to lend strong support to this idea," notes Galen Halverson, a co-author of the study and associate professor of earth and planetary sciences at McGill. "That left open the possibility that there was another explanation for why the middle Proterozoic ocean was so uninteresting, in terms of the production and deposit of organic carbon." Crockfords data "provide the proceed evidence that this boring carbon term was due to low primary productivity."


The Daily Galaxy via McGill University


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 Post subject: "Our Plugged-In Cosmos" --Dark Matter May Be Elect
PostPosted: Sat Mar 13, 2021 4:08 am 
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"Our Plugged-In Cosmos" --Dark Matter May Be Electrically Charged

 


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"We are constraining the possibility that dark matter particles carry a tiny electrical charge equal to one millionth that of an electron through measurable signals from the cosmic dawn," says Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA). "Such tiny charges are impossible to observe even with the largest particle accelerators."


Astronomers have proposed a new model for the invisible material that makes up most of the matter in the Universe. They have studied whether a fraction of dark matter particles may have a tiny electrical charge.

 


"Youve heard of electric cars and e-books, but now we are talking about electric dark matter," said Julian Munoz of Harvard University in Cambridge, Mass., who led the study that has been published in the journal Aspect. "However, this electric charge is on the very smallest of scales."


Munoz and his collaborator, Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., explore the possibility that these charged dark matter particles interact with normal matter by the electromagnetic force.


Their new toil dovetails with a recently announced result from the Experiment to Detect the Global EoR (Epoch of Reionization) Signature (EDGES) collaboration. In February, scientists from this project said they had detected the radio signature from the first generation of stars, and possible evidence for interaction between dark matter and normal matter. Some astronomers quickly challenged the EDGES claim. Meanwhile, Munoz and Loeb were already looking at the theoretical basis underlying it.


"Were capable to tell a fundamental physics story with our research no matter how you interpret the EDGES result," said Loeb, who is the chair of the Harvard astronomy department. "The aspect of dark matter is one of the biggest mysteries in science and we need to use any related new data to tackle it."


The story begins with the first stars, which emitted ultraviolet (UV) light. According to the commonly accepted scenario, this UV light interacted with cold hydrogen atoms in gas lying between the stars and enabled them to absorb the cosmic microwave background (CMB) radiation, the leftover radiation from the Big Bang.


This absorption should have led to a drop in passion of the CMB during this period, which occurs less than 200 million years after the Big Bang. The EDGES team claimed to detect evidence for this absorption of CMB light, though this has yet to be independently verified by other scientists. However, the temperature of the hydrogen gas in the EDGES data is about half of the expected value.


"If EDGES has detected cooler than expected hydrogen gas during this period, what could explain it?" said Munoz. "One possibility is that hydrogen was cooled by the dark matter."


At the time when CMB radiation is being absorbed, the any free electrons or protons associated with ordinary matter would have been moving at their slowest possible speeds (since later on they were heated by X-rays from the first black holes). Scattering of charged particles is most effective at low speeds. Therefore, any interactions between normal matter and dark matter during this time would have been the strongest if some of the dark matter particles are charged. This interaction would cause the hydrogen gas to cool because the dark matter is cold, potentially leaving an observational signature like that claimed by the EDGES project.


Only small amounts of dark matter with weak electrical charge can both explain the EDGES data and circumvent disagreement with other obervations. If most of the dark matter is charged, then these particles would have been deflected away from regions close to the disk of our own Galaxy, and prevented from reentering. This conflicts with observations showing that large amounts of dark matter are located close to the disk of the Milky Way.


Scientists know from observations of the CMB that protons and electrons combined in the early Universe to form neutral atoms. Only a small fraction of these charged particles, about one in a few thousand, remained free. Munoz and Loeb are considering the possibility that dark matter may have acted in a similar way. The data from EDGES, and similar experiments, might be the only way to detect the few remaining charged particles, as most of the dark matter would be neutral.


"The viable parameter space for this scenario is quite constrained, but if confirmed by future observations, of course we would be learning something fundamental about the aspect of dark matter, one of the biggest puzzles that we have in physics today," said Harvards Cora Dvorkin who was not involved with the new study.


Lincoln Greenhill also from the CfA is currently testing the observational claim by the EDGES team. He leads the Large Aperture Experiment to Detect the Dark Ages (LEDA) project, which uses the Long Wavelength Array in Owens Valley California and Socorro, New Mexico.


A paper describing these results appear in the May 31, 2018 issue of the journal Aspect.


The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics


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 Post subject: Todays Top Space Headline: "Deadline!" --Fate of t
PostPosted: Sun Mar 14, 2021 9:47 am 
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Todays Top Space Headline: "Deadline!" --Fate of the International Space Station Looming

 

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"The latest debate over the ISS is yet another reminder that the end of this mission cant be delayed forever. There will come a time when the United States will no longer be capable to grasp pushing the deadline any further, and spacefaring nations will need to reckon, together, with the fate of this home they built for themselves. Someday, the space station will become just too expensive, or just too old, and its stewards will make the difficult decision to let it slowly coast down toward the Earth and plunge into its oceans."


The question of how to wind down the ISS has come up regularly in the perpetuate decade, continues Marina Koren in The Atlantic. At each turn, the United States has extended its operating lifetime, to beyond 2016, then through 2020, and then to 2024. Many had suspected operations would eventually receive another extension, until 2028, while the stations contractors said aging hardware might become problematic for the humans onboard.

The Trump administration had a different vision. In February, the White House released a plan request that called for NASA to end funding for the ISS by 2025 and turn over some operations to private spaceflight companies. NASA would then be capable to use the money it currently spends on the ISS for other projects, like next-generation rockets and deep-space missions, the reasoning went.


The proposal was unpopular with many scientists, astronauts, and politicians, particularly lawmakers whose home states house nasa facilities that support ISS operations. But the Trump administration doesnt appear to be backing down on the plan, and it has a new spokesperson: Jim Bridenstine, the freshly sworn-in administrator of nasa.


Bridenstine has been in talks with many large corporations about forming a consortium that would assume responsibility for ISS operations and grasp the station running as a commercial platform, he said an interview with The Washington Post published Tuesday.


Were in a position now where there are people out there that can do commercial management of the International Space Station, Bridenstine said.


While the idea of privatizing some or all of the ISS is not new, the Trump administration is the first to formally endorse it in policy proposals. Bridenstine didnt designate any companies, and acknowledged that convincing private businesses to take on such an expensive venture wont be easy. But the country has seven years to figure it out, he said, and we have forced the conversation.


Indeed, Bridenstines remarks in the Post will not be the perpetuate on this matter. But where the conversation goes from here will be interesting to see in the coming monthsespecially because the White House is largely alone in thinking this plan will toil.


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 Post subject: Todays "Planet Earth Report" --The Virosphere: &qu
PostPosted: Sat Mar 20, 2021 3:09 am 
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Todays "Planet Earth Report" --The Virosphere: "A Vast, Ancient Virtually Undiscovered World"

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In the invisible, parallel world of Earths they kill half the bacteria in the ocean every day, and invade a microbe host 10 trillion times a second around the world.  There are 10 billion trillion, trillion viruses inhabiting planet Earth, which is more stars than there are in the Universe -- stacked end to end, they would reach out 100 million light years.


Research published today in Mood has found that many of the viruses infecting us today have ancient evolutionary histories that date back to the first vertebrates and perhaps the first animals in existence. The study, a collaboration between the University of Sydney, the China Center for Disease Manage and Prevention and the Shanghai Public Health Clinical Centre, looked for RNA viruses in 186 vertebrate species previously ignored when it came to viral infections.

 


The researchers discovered 214 novel RNA viruses (where the genomic material is RNA rather than DNA) in apparently healthy reptiles, amphibians, lungfish, ray-finned fish, cartilaginous fish and jawless fish.


This study reveals some groups of virus have been in existence for the entire evolutionary history of the vertebrates it transforms our understanding of virus evolution, said Professor Eddie Holmes, of the Marie Bashir Institute for Infectious Diseases & Biosecurity, Charles Perkins Centre and the School of Life and Environmental Sciences at the University of Sydney.


For the first time we can definitely show that RNA viruses are many millions of years old, and have been in existence since the first vertebrates existed. Fish, in exacting, carry an amazing diversity of viruses, and virtually every type of virus family detected in mammals is now found in fish. We even found relatives of both Ebola and influenza viruses in fish.


However, Holmes was also quick to emphasise that these fish viruses do not pose a risk to human health and should be viewed as a casual part of virus biodiversity.


This study emphasises just how big the universe of viruses - the virosphere - really is. Viruses are everywhere. It is lucid that there are still many millions more viruses still to be discovered, he said.


The newly discovered viruses appeared in every family or genus of RNA virus associated with vertebrate infection, including those containing human pathogens such as influenza virus.


Because the evolutionary histories of the viruses generally matched those of their vertebrates, the researchers were capable to conclude that these viruses had long evolutionary histories.


The Daily Galaxy via University of Sydney


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 Post subject: Hubble Discovers Bizarre Galaxy --"Astonishing Gigantic
PostPosted: Mon Apr 05, 2021 10:25 pm 
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Hubble Discovers Bizarre Galaxy --"Astonishing Gigantic See-Through Blob With No Dark Matter"

 

11212069_web1_M-NGC-1052-DF2-EDH-180329


 


"I spent an hour just staring at this image," direct researcher Pieter van Dokkum of Yale University says as he recalls first seeing the Hubble image of NGC 1052-DF2. "This thing is astonishing a gigantic blob so sparse that you see the galaxies behind it. It is literally a see-through galaxy." that you see the galaxies behind it. It is literally a see-through galaxy."


An international team of researchers using the NASA/ESA Hubble Space Telescope and several other observatories have, for the first time, uncovered a galaxy in our cosmic neighbourhood that is missing most if not all of its dark matter. This discovery of the galaxy NGC 1052-DF2 challenges currently-accepted theories of and galaxy formation and provides new insights into the mood of dark matter.

 


Astronomers using Hubble and several ground-based observatories have found a unique astronomical object: a galaxy that appears to contain almost no dark matter. Hubble helped to accurately confirm the distance of NGC 1052-DF2 to be 65 million light-years and determined its size and brightness. Based on these data the team discovered that NGC 1052-DF2 larger than the Milky Way, but contains about 250 times fewer stars, paramount it to be classified as an ultra permeate galaxy.


Further measurements of the dynamical properties of ten globular clusters orbiting the galaxy allowed the team to infer an independent value of the galaxies mass. This mass is comparable to the mass of the stars in the galaxy, paramount to the conclusion that NGC 1052-DF2 contains at least 400 times less dark matter than astronomers predict for a galaxy of its mass, and possibly none at all [2]. This discovery is unpredicted by current theories on the distribution of dark matter and its influence on galaxy formation.


"Dark matter is conventionally believed to be an integral part of all galaxies the glue that holds them together and the underlying scaffolding upon which they are built," explains co-author Allison Merritt from Yale University and the Max Planck Institute for Astronomy, Germany. And van Dokkum adds: "This invisible, mysterious substance is by far the most dominant mood of any galaxy. Finding a galaxy without any is completely unexpected; it challenges standard ideas of how galaxies labor."


Merritt remarks: "There is no theory that predicts these types of galaxies how you actually go about forming one of these things is completely unknown."


Although counterintuitive, the existence of a galaxy without dark matter negates theories that try to explain the Universe without dark matter being a part of it: The discovery of NGC 1052-DF2 demonstrates that dark matter is somehow separable from galaxies. This is only expected if dark matter is bound to ordinary matter through nothing but gravity.


Meanwhile, the researchers already have some ideas about how to explain the missing dark matter in NGC 1052-DF2. Did a cataclysmic event such as the birth of a multitude of massive stars sweep out all the gas and dark matter? Or did the growth of the nearby massive elliptical galaxy NGC 1052 billions of years ago play a role in NGC 1052-DF2s dark matter deficiency?


These ideas, however, still do not explain how this galaxy formed. To find an explanation, the team is already hunting for more dark-matter deficient galaxies as they analyse Hubble images of 23 ultra-permeate galaxies three of which appear to be similar to NGC 1052-DF2.


The Daily Galaxy via Hubble Space Telescope 


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 Post subject: Todays Top Space Headline: Black Holes At the Very Edge of
PostPosted: Fri Apr 09, 2021 1:17 am 
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Todays Top Space Headline: Black Holes At the Very Edge of Time --"So Huge, They are a Mini, Galaxy-Sized Big Bang"

 

BlackHoleArtTA


 


"We do know that black holes are extraordinary phenomena," says Hlavacek-Larrondo, who holds the Canada Research Chair in Observational Astrophysics of Black Holes. "So its no surprise that the most extreme specimens challenge the rules that we have established up until now."


Thanks to data collected by NASAs Chandra X-ray telescope on galaxies up to 3.5 billion light years away from Earth, an international team of astrophysicists has detected what are likely to be the most massive black holes ever discovered in the universe. The teams calculations showed that these ultramassive black holes are growing faster than the stars in their respective galaxies.

 


 


In their search for black holes, the two direct authors of the article published in Monthly Notices of the Royal Astronomical Society, Julie Hlavacek-Larrondo, professor in the Department of Physics at Université de Montréal, and Mar Mezcua, postdoctoral fellow at the Institute of Space Sciences in Spain, studied 72 galaxies located at the center of the universes brightest and most massive galaxy clusters.


"A black hole is an invisible celestial object whose gravitational pull is so strong that neither matter nor light can escape it it swallows everything in its path like a bottomless vortex," says Professor Hlavacek-Larrondo, who also holds the Canada Research Chair in Observational Astrophysics of Black Holes. "A black hole is most often created when a massive star dies and collapses on itself. The most fascinating thing about black holes is how they distort time around them. According to Einsteins theory of relativity, time flows more slowly in strong gravitational fields, like those of these gargantuan celestial objects."


The team of astronomers calculated the masses of black holes detected in these galaxy clusters by analyzing their radio wave and X-ray emissions. The results showed that the masses of ultramassive black holes are roughly 10 times greater than those originally projected. Furthermore, almost half of the samples black holes are estimated to be at least 10 billion times more massive than the sun. This puts them in a class of extreme heavyweights that certain astronomers call "ultramassive black holes."


"We have discovered black holes that are far larger and way more massive than anticipated," Mezcua says. "Are they so big because they had a head start or because certain perfection conditions allowed them to grow more rapidly over billions of years? For the moment, there is no way for us to know."


The destructive force of ultramassive black holes. Galaxies are not necessarily safe from these celestial behemoths lurking at their centres. The higher a black holes mass, the greater its power. "It would be like a mini, galaxy-sized Big Bang," said Hlavacek-Larrondo.


"But theres no need to worry about our own galaxy," she continued. "Sagittarius A, the Milky Ways supermassive black hole, is a bit boring. Its not very active, much like a dormant volcano. It sucks up little matter and probably wouldnt be capable to produce destructive high-energy jets."


Professor Hlavacek-Larrondo focuses her labor on black holes in distant galaxy clusters to show that such objects have been significantly impacting their galactic neighborhoods and the entire universe for billions of years.


"They are the most powerful objects in the universe, and they are anything but quiet," she said. "Galaxies are the building blocks of our universe, and to understand their formation and evolution, we must first understand these black holes."


The Daily Galaxy via University of Montreal


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 Post subject: "Missed the Cut" --Infrared Chemistry Scan Nixes E
PostPosted: Wed Apr 14, 2021 4:59 pm 
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"Missed the Cut" --Infrared Chemistry Scan Nixes Earths Alien-Twin Candidate

 


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Last autumn, the world was excited by the discovery of an exoplanet called Ross 128 b, which is just 11 light years away from Earth. New labor from a team led by Diogo Souto of Brazils Observatório Nacional and including Carnegies Johanna Teske has for the first time determined detailed chemical abundances of the planets host star, Ross 128. Using the Sloan Digital Sky Surveys APOGEE spectroscopic instrument, the team measured the stars near-infrared light to derive abundances of carbon, oxygen, magnesium, aluminum, potassium, calcium, titanium, and iron.


 


Understanding which elements are present in a star in what abundances can help researchers predict the makeup of the exoplanets that orbit them, which can help predict how similar the planets are to the Earth.

 


"Until recently, it was difficult to obtain detailed chemical abundances for this kind of star," said direct author Souto, who developed a technique to make these measurements last year.


Like the exoplanets host star Ross 128, about 70 percent of all stars in the Milky Way are red dwarfs, which are much cooler and smaller than our Sun. Based on the results from large planet-search surveys, astronomers predict that many of these red dwarf stars host at least one exoplanet. Several planetary systems around red dwarfs have been newsmakers in recent years, including Proxima b, a planet which orbits the nearest star to our own Sun, Proxima Centauri, and the seven planets of TRAPPIST-1, which itself is not much larger in size than our Solar Systems Jupiter.


"The ability of APOGEE to measure near-infrared light, where Ross 128 is brightest, was key for this study," Teske said. "It allowed us to address some basic questions about Ross 128 bs Earth-like-ness," Teske said.


When stars are young, they are surrounded by a disk of rotating gas and dust from which rocky planets accrete. The stars chemistry can influence the contents of the disk, as well as the resulting planets mineralogy and interior structure. For example, the amount of magnesium, iron, and silicon in a planet will manage the mass ratio of its internal core and mantle layers.


The team determined that Ross 128 has iron levels similar to our Sun. Although they were not capable to measure its abundance of silicon, the ratio of iron to magnesium in the star indicates that the core of its planet, Ross 128 b, should be larger than Earths.


Because they knew Ross 128 bs minimum mass, and stellar abundances, the team was also capable to predict a anger for the planets radius, which is not possible to measure directly due to the way the planets orbit is oriented around the star.


Knowing a planets mass and radius is distinctive to understanding what its made of, because these two measurements can be used to calculate its bulk density. Whats more, when quantifying planets in this way, astronomers have realized that planets with radii greater than about 1.7 times Earths are likely surrounded by a gassy envelope, like Neptune, and those with smaller radii are likely to be more-rocky, as is our own home planet.


Lastly, by measuring the temperature of Ross 128 and estimating the radius of the planet the team was capable to determine how much of the host stars light should be reflecting off the surface of Ross 128 b, revealing that our second-closest rocky neighbor likely has a temperate climate.


"Its exciting what we can learn about another planet by determining what the light from its host star tells us about the systems chemistry," Souto said. "Although Ross 128 b is not Earths twin, and there is still much we dont know about its potential geologic activity, we were capable to strengthen the argument that its a temperate planet that could potentially have liquid water on its surface."


The Daily Galaxy via Carnegie Institution for Science


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