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  • richardmitnick 4:04 pm on February 15, 2019 Permalink | Reply
    Tags: Muons reveal the whopping voltages inside a thunderstorm, , Science News, The GRAPES-3 Experiment   

    From Science News: “Muons reveal the whopping voltages inside a thunderstorm” 

    From Science News

    February 15, 2019
    Emily Conover

    Physicists used subatomic particles to probe the inner workings of a cloud.

    STORM SURGE Subatomic particles called muons can expose a thunderstorm (like this one) storing up a huge electric potential — more than a billion volts. Ian Froome/Unsplash

    An invisible drizzle of subatomic particles has shown that thunderstorms may store up much higher electric voltages than we thought.

    Using muons, heavier relatives of electrons that constantly rain down on Earth’s surface, scientists probed the insides of a storm in southern India in December 2014. The cloud’s electric potential — the amount of work necessary to move an electron from one part of the cloud to another — reached 1.3 billion volts, the researchers report in a study accepted in Physical Review Letters. That’s 10 times the largest voltage previously found by using balloons to make similar measurements.

    High voltages within clouds spark lightning. But despite the fact that thunderstorms regularly rage over our heads, “we really don’t have a good handle on what’s going on inside them,” says physicist Joseph Dwyer of the University of New Hampshire in Durham who was not involved with the research.

    Balloons and aircraft can monitor only part of a cloud at a time, making it difficult to get an accurate measurement of the whole thing. But muons zip right through, from top to bottom. “Muons that penetrate the thunderclouds are a perfect probe for measuring the electric potential,” says physicist Sunil Gupta of the Tata Institute of Fundamental Research in Mumbai, India.

    BEARING FRUIT The GRAPES-3 experiment (shown) measures muons that rain down on Earth. The pitter-patter of the electrically charged subatomic particles drops off during thunderstorms, unmasking the electrical inner workings of clouds. The GRAPES-3 Experiment.

    Gupta and colleagues studied the muons’ behavior with the GRAPES-3 experiment in Ooty, India, which observes around 2.5 million muons every minute. During thunderstorms, that rate drops, as muons, which are electrically charged, tend to be slowed by a thunderstorm’s electric fields. That means fewer particles carry enough energy to register in the scientists’ detectors.

    Using computer simulations of a thunderstorm, the researchers determined the electric potential necessary to explain the drop in muons spotted during the 2014 storm. The team also estimated the storm’s electric power: It was similar to the output of a large nuclear reactor, at around 2 billion watts.

    The result is “potentially very important,” Dwyer says. But “with anything that’s new, you have to wait and see what happens with additional measurements.” And the researchers’ simulated thunderstorm was simplified, he says. It consisted of one region of positive charge, and another negatively charged region, whereas real thunderstorms are more complex.

    If confirmed, though, such high voltages inside a thunderstorm could explain a puzzling observation: Some storms send bursts of high-energy light, called gamma rays, upward (SN: 5/30/15, p. 12). But scientists don’t fully understand the processes that could create such energetic light. If thunderstorms indeed reach the billion-volt level, that could account for the mysterious light.

    See the full article here .


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  • richardmitnick 9:59 am on January 29, 2019 Permalink | Reply
    Tags: , , Earth’s core may have hardened just in time to save its magnetic field, Magnetic field of Earth’s inner core, , Science News   

    From Science News: “Earth’s core may have hardened just in time to save its magnetic field” 

    From Science News

    January 28, 2019
    Carolyn Gramling

    This shift both prevented the protective magnetic field from collapsing and recharged it.

    SOLAR SHIELD Earth’s magnetic field (illustrated) is powered by circulation of iron-rich fluid in the core. New research suggests Earth’s solid inner core formed about 565 million years ago, saving a weakening magnetic field from collapse. Credit: Marc Ward/Shutterstock

    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase

    Earth’s inner core solidified around 565 million years ago — just in time to not only save the planet’s protective magnetic field from imminent collapse, but also to kick-start it into its current, powerful phase, a new study suggests.

    The finding, reported online January 28 in Nature Geoscience, supports an idea previously proposed by simulations that Earth’s inner core is relatively young. It also provides insight into how, and how quickly, Earth has been losing heat since its formation 4.54 billion years ago —key to understanding not only the generation of the planet’s magnetic shield but also convection within the mantle and plate tectonics.

    “We don’t have many real benchmarks for the thermal history of our planet,” says Peter Olson, a geophysicist at Johns Hopkins University who was not involved in the new study. “We know the interior was hotter than today, because all planets lose heat. But we don’t know what the average temperature was a billion years ago, compared with today.” Pinning down when iron in the inner core began to crystallize could offer a window into how hot the interior of the planet was at the time, Olson says.

    The planet’s iron-nickel core is made up of two layers: a solid inner core and a molten outer core. When that solid inner core formed is a long-standing mystery (SN: 9/19/15, p. 18). “Proposed ages have been anywhere from 500 million years ago to older than 2.5 billion years,” says coauthor John Tarduno, a geophysicist at the University of Rochester in New York.

    The interplay of the two layers drives the geodynamo, the circulation of iron-rich fluid that powers the magnetic field. That field, surrounding the planet, protects Earth from being battered by the solar wind, a constant flow of charged particles ejected by the sun. As the inner core cools and crystallizes, the composition of the remaining fluid changes; more buoyant liquid rises like a plume while the cooling crystals sink. That self-sustaining, density-driven circulation generates a strong magnetic field with two opposing poles, north and south, or polarity.

    Traces of magnetism in ancient rocks suggest that Earth had a magnetic field as far back as 4.2 billion years ago. That earlier field was likely generated by heat within the planet driving circulation within the molten core. But over time, computer simulations suggest, the heat-driven circulation wouldn’t have been strong enough alone to continue to power a strong magnetic field. Instead, the field began to shut down, signaled in the rock record by weakening intensities and rapid polarity reversals over millions of years. And then, at some point, Earth’s inner core began to crystallize, jump-starting the geodynamo and generating a new, strong magnetic field.

    Feeling stable

    Heat driving convection within Earth’s hot, molten core (orange) powered the planet’s magnetic field for billions of years. New evidence suggests that by about 565 million years ago, that field was weak and increasingly unstable (left). Sometime after that, the inner core began to solidify (red, at right), which stabilized and strengthened the field, giving it relatively consistent magnetic north and south poles (right).

    Roberto Molar Candanosa and Peter Driscoll/Nature Geoscience 2019

    Now scientists think they’ve found evidence of when that magnetic field breakdown was happening. Researchers led by geophysicist Richard Bono, now at the University of Liverpool in England, examined magnetic inclusions within a suite of rocks in Quebec, Canada, dating to about 565 million years ago. Analyses of the inclusions — needlelike iron-rich grains that align themselves with the orientation of the magnetic field that existed when the rocks formed — show that the planet’s magnetic field was extremely weak at that time, the researchers report.

    “These paleo-intensity values were 10 times less than the present magnetic field, lower than anything observed previously,” Tarduno says. “It suggested there’s something fundamental going on in the core.”

    Combined with previous studies that have found that the magnetic field was also rapidly reversing polarity during that time period, the new result indicates that Earth’s field may have been on the point of collapse about 565 million years ago. That suggests that the inner core hadn’t yet solidified. Fortunately for life on Earth, it eventually did.

    “Presumably things worked out well for our planet,” Tarduno says. “But that doesn’t necessarily mean it had to.”

    The new finding is “potentially very important,” Olson says. Because the rocks bearing the magnetic grains didn’t cool instantaneously but over a long time, the data represent an average field intensity for about a 100,000-year period. That means the scientists haven’t just captured a snapshot in time of a fluctuating field, but have found a true, persistent signal, he says. Computer simulations have suggested that the weak field phase may have lasted much longer, from about 900 million to 600 million years ago. More paleo-intensity data from within that time span, as well as from other locations, would help to confirm that the observed weak phase really signaled the final throes of that pre–inner core field.

    Peter Driscoll, a geophysicist at the Carnegie Institution for Science in Washington, D.C., was one of the theoreticians who estimated how long the weak phase might have lasted. Driscoll, whose commentary accompanies the study in Nature Geoscience, notes that a young solid inner core also highlights lingering conundrums about how quickly Earth cooled. For example, “if the core is cooling quickly, that means it was very hot in the recent past, and that the lower mantle was very hot in the recent past” — so hot that both were molten just 1 billion to 2 billion years ago. “We absolutely do not see that in the rock record.”

    Driscoll adds that he hopes the new study garners attention to the glaring gap in paleomagnetic data from this time period. “There’s a lot more time here that we could be filling in.”

    R.K. Bono et al., Nature Geoscience above

    P. Driscoll. Geodynamo recharged. Nature Geoscience. Published online January 28, 2019. doi:10.1038/s41561-019-0301-2.

    See the full article here .


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  • richardmitnick 10:45 am on January 22, 2019 Permalink | Reply
    Tags: , CERN Compact Linear Collider, , China-Circular Electron Positron Collider, Future colliders, , , International Linear Collider in northern Japan, , , Science News   

    From Science News: “Physicists aim to outdo the LHC with this wish list of particle colliders” 

    From Science News


    January 22, 2019
    Emily Conover

    CERN Future Circular Collider artist’s rendering

    If built, the accelerators could pump out oodles of Higgs bosons.

    If particle physicists get their way, new accelerators could one day scrutinize the most tantalizing subatomic particle in physics — the Higgs boson.

    CERN CMS Higgs Event

    CERN ATLAS Higgs Event

    Six years after the particle’s discovery at the Large Hadron Collider, scientists are planning enormous new machines that would stretch for tens of kilometers across Europe, Japan or China.

    The 2012 discovery of the subatomic particle, which reveals the origins of mass, put the finishing touch on the standard model, the overarching theory of particle physics (SN: 7/28/12, p. 5).

    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    And it was a landmark achievement for the LHC, currently the world’s biggest accelerator.


    CERN map

    CERN LHC Tunnel

    CERN LHC particles

    Now, physicists want to delve further into the mysteries of the Higgs boson in the hope that it could be key to solving lingering puzzles of particle physics. “The Higgs is a very special particle,” says physicist Yifang Wang, director of the Institute of High Energy Physics in Beijing. “We believe the Higgs is the window to the future.”

    But the LHC — which consists of a ring 27 kilometers in circumference, inside which protons are accelerated to nearly the speed of light and smashed together a billion times a second — can take scientists only so far. That accelerator was great for discovering the Higgs, but not ideal for studying it in detail.

    So particle physicists are clamoring for a new particle collider, specifically designed to crank out oodles of Higgs bosons. Several blueprints for powerful new machines have been put forth, and researchers are hopeful these “Higgs factories” could help reveal solutions to glaring weak spots in the standard model.

    “The standard model is not a complete theory of the universe,” says experimental particle physicist Halina Abramowicz of Tel Aviv University. For example, the theory can’t explain dark matter, an unidentified substance whose mass is necessary to account for cosmic observations such as the motions of stars in galaxies. Nor can it explain why the universe is made up of matter, while antimatter is exceedingly rare.

    Carefully scrutinizing the Higgs boson might point scientists in the direction of solutions to those puzzles, proponents of the new colliders claim. But, among scientists, the desire for new, costly accelerators is not universal, especially since it’s unclear what exactly the machines might find.

    Next in line

    Closest to inception is the International Linear Collider in northern Japan. Unlike the LHC, in which particles zip around a ring, the ILC would accelerate two beams of particles along a straight line, directly at one another over its 20-kilometer length. And instead of crashing protons together, it would collide electrons and their antimatter partners, positrons.

    But, in an ominous sign, a multidisciplinary committee of the Science Council of Japan came down against the project in a December 2018 report, urging the government to be cautious with its support and questioning whether the expected scientific achievements justified the accelerator’s cost, currently estimated at around $5 billion.

    Supporters argue that the ILC’s plan to smash together electrons and positrons, rather than protons, has some big advantages. Electrons and positrons are elementary particles, meaning they have no smaller constituents, while protons are made up of smaller particles called quarks. That means that proton collisions are messier, with more useless particle debris to sift through.


    THIN LINE An accelerator planned for Japan, the International Linear Collider (design illustrated), would slam together electrons and positrons to better understand the Higgs boson.

    Additionally, in proton smashups, only a fraction of each proton’s energy actually goes into the collision, whereas in electron-positron colliders, particles bring the full brunt of the accelerator’s energy to bear. That means scientists can tune the energy of collisions to maximize the number of Higgs bosons produced. At the same time, the ILC would require only 250 billion electron volts to produce Higgs bosons, compared with the LHC’s 13 trillion electron volts.

    For the ILC, “the quality of the data coming out will be much higher, and there will be much more of it on the Higgs,” says particle physicist Lyn Evans of CERN in Geneva. One in every 100 ILC collisions would pump out a Higgs, whereas that happens only once in 10 billion collisions at the LHC.

    The Japanese government is expected to decide about the collider in March. If the ILC is approved, it should take about 12 years to build, Evans says. The accelerator could also be upgraded later to increase the energy it can reach.

    CERN has plans for a similar machine known as the Compact Linear Collider.

    Cern Compact Linear Collider

    It would also collide electrons and positrons, but at higher energies than the ILC. Its energy would start at 380 billion electron volts and increase to 3 trillion electron volts in a series of upgrades. But to reach those higher energies, new particle acceleration technology needs to be developed, meaning that CLIC is even further in the future than the ILC, says Evans, who leads a collaboration of researchers from both projects.

    Running in circles

    Two other planned colliders, in China and Europe, would be circular like the LHC, but would dwarf that already giant machine; both would be 100 kilometers around. That’s a circle big enough that the country of Liechtenstein could easily fit inside — twice.

    At a location yet to be determined in China, the Circular Electron Positron Collider, or CEPC, would collide electrons and positrons at 240 billion electron volts, according to a conceptual plan officially released in November and championed by Wang and the Institute of High Energy Physics.

    China Circular Electron-Positron collider depiction

    China Circular Electron Positron Collider (CEPC) map

    The accelerator could later be upgraded to collide protons at higher energies. Scientists say they could begin constructing the $5 billion to 6 billion machine by 2022 and have it ready to go by 2030.

    And at CERN, the proposed Future Circular Collider, or FCC, would likewise operate in stages, colliding electrons and positrons before moving on to protons. The ultimate goal would be to reach proton collisions with 100 trillion electron volts, more than seven times the LHC’s energy, according to a Jan. 15 report from an international group of researchers.

    FCC Future Circular Collider at CERN

    Meanwhile, scientists have shut down the LHC for two years, while they upgrade the machine to function at a slightly higher energy (SN Online: 12/3/18). Further down the line, a souped-up version known as the High-Luminosity LHC could come online in 2026 and would increase the proton collision rate by at least a factor of five (SN Online: 6/15/18).

    Portrait of the Higgs

    When the LHC was built, scientists were fairly confident they’d find the Higgs boson with it. But with the new facilities, there’s no promise of new particles. Instead, the machines will aim to catalog how strongly the Higgs interacts with other known particles; in physicist lingo, these are known as its “couplings.”

    Measurements of the Higgs’ couplings may simply confirm expectations of the standard model. But if the observations differ from expectations, the discrepancy could indirectly hint at the presence of something new, such as the particles that make up dark matter.

    Some scientists are hopeful that something unexpected might arise. That’s because the Higgs is an enigma: The particles condense into a kind of molasses-like fluid. “Why does this fluid do that? We have no clue,” says theoretical particle physicist Michael Peskin of Stanford University. That fluid pervades the universe, slowing particles down and giving them heft.

    Another puzzle is that the Higgs’ mass is a million billion times smaller than expected (SN Online: 10/22/13). Certain numbers in the standard model must be fine-tuned to extreme precision make the Higgs less hefty, a situation physicists find unnatural.

    The weirdness of the Higgs suggests other particles might be out there. Scientists previously thought they had an answer to the Higgs quandaries, via a theory called supersymmetry, which posits that each known particle has a heavier partner (SN: 10/1/16, p. 12). “Before the LHC started, there were huge expectations,” says Abramowicz: Some scientists claimed the LHC would quickly find supersymmetric particles. “Well, it didn’t happen,” she says.

    The upcoming colliders may yet find evidence of supersymmetry, or otherwise hint at new particles, but this time around, scientists aren’t making promises.

    BIG SMASH In the new accelerators, collisions would produce showers of exotic particles (illustrated), including the Higgs boson, which explains how particles get mass.

    “In the past, some people have clearly oversold what the LHC was expected to deliver,” says theoretical particle physicist Juan Rojo of Vrije University Amsterdam. When it comes to any new colliders, “we should avoid making the same mistake if we want to keep our field alive for decades to come,” he says.

    Researchers around the world are now hashing out priorities, making arguments for the new colliders and other particle physics experiments. European physicists, for example, will meet in May to discuss options, working toward a document called the European Particle Physics Strategy Update, to guide research there in 2020 and beyond.

    One thing is certain: The proposed accelerators would explore unknown territory, with unpredictable results. The unanswered questions surrounding the Higgs boson make it the most obvious place to look for hints of new physics, Peskin says. “It’s the place that we haven’t looked yet, so it’s really compelling.”


    CERN. Future Circular Collider Conceptual Design Report. Published online January 15, 2018.

    European Particle Physics. Strategy Update 2018–2020.

    Linear Collider Collaboration. Executive Summary of the Science Council of Japan’s Report. LC Newsline. Published online December 21, 2018.

    The Institute of High Energy Physics of the Chinese Academy of Sciences. CEPC Conceptual Design Report Volume I – Accelerator. November 14, 2018.

    The Institute of High Energy Physics of the Chinese Academy of Sciences. CEPC Conceptual Design Report Volume II – Physics & Detector. November 14, 2018.

    See the full article here .


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  • richardmitnick 2:59 pm on January 12, 2019 Permalink | Reply
    Tags: Department of Agriculture, Environmental Protection Agency, Fish and Wildlife Service, Food and Drug Administration, Here’s how the record-breaking government shutdown is disrupting science, Indian Health Service, , National Oceanic and Atmospheric Administration, National Parks Service, National Radio Astronomy Observatory, , National Weather Service, Science News, U.S. Geological Survey   

    From Science News: “Here’s how the record-breaking government shutdown is disrupting science” 

    From Science News

    January 12, 2019
    Laurel Hamers

    The shutdown is forcing scientists to cancel presentations and halt research.

    TEMPORARY WORKAROUND For now, the National Radio Astronomy Observatory based in Charlottesville, Va., shown here closed during a 2013 government shutdown, is still open, funded by money left over from 2018. But if the current shutdown doesn’t end soon, it may be forced to close again. Emily Barney/Flickr (CC BY-NC 2.0)

    As the partial federal government shutdown enters its fourth week — on January 12 becoming the longest in U.S. history — scientists are increasingly feeling the impact. Thousands of federal workers who handle food safety and public health are furloughed. Countless projects researching everything from climate change to pest control to hurricane prediction are on hold.

    Among government agencies hit by the partial shutdown are the U.S. Geological Survey, the Department of Agriculture, the National Oceanic and Atmospheric Administration, the Environmental Protection Agency and NASA, where nearly all employees are on leave. Additionally, 40 percent of the Food and Drug Administration’s 14,000 workers are furloughed, as are most employees of the National Parks Service and the Fish and Wildlife Service.

    Meanwhile, the National Science Foundation, responsible for doling out nearly $8 billion in research funds each year, has stopped awarding grants and has canceled review panels with outside scientists that are part of the process. In 2018, NSF gave out $42 million in grants from January 1 through January 8, but this year, nothing has been funded so far, Benjamin Corb of the American Society for Biochemistry and Molecular Biology noted in a statement January 8. Such stalled funding is leading to a backlog that could slow down approvals long beyond the shutdown. Here are some of the consequences of delaying government research, and how some scientists are trying to cope.

    Public safety

    Both the National Institutes of Health and the Centers for Disease Control and Prevention remain funded and operational. Flu surveillance is still being funded through the CDC. Medicare and Medicaid insurance programs are also safe.

    But other agencies working to protect public health have scaled back operations. The Indian Health Service, which funds care for Native Americans, is in limbo. Health clinic employees are working without pay, while some grants and programs are on hold.

    The USDA is still inspecting meat, dairy and poultry products. But routine FDA inspections of produce are suspended, increasing the possibility of a foodborne illness outbreak. Given that worry, the agency hopes to resume inspections of high-risk facilities prone to outbreaks, FDA commissioner Scott Gottlieb told the Washington Post.

    PRODUCE PROBLEMS During the shutdown, the U.S. Food and Drug Administration hasn’t been carrying out routine inspections of produce, upping the risk for a foodborne illness outbreak. Caroline Attwood/Unsplash

    Weather forecasts have become less accurate, with the National Weather Service’s key prediction tool not working correctly and no one around to fix it, the Washington Post also reported, citing Suru Saha of the National Weather Service’s Environmental Modeling Center in College Park, Md.

    Meanwhile, work to improve hurricane models by adding the latest in physics and data isn’t happening, forecaster Eric Blake at the National Weather Service’s National Hurricane Center in Miami told Scientific American.

    Environment damage

    EPA employees policing industry compliance with laws restricting air and water pollution are on leave, and work to clean up Superfund sites, areas of extreme environmental contamination, is suspended. That means any research into the potential health or environmental effects of new contaminants is on hold.

    POLLUTION UNPATROLLED The U.S. Environmental Protection Agency officials who hold companies accountable for complying with pollution regulations, as well as those who work on Superfund sites like the Gowanus Canal in New York (shown here), aren’t working right now. nicolecioe/iStock.com

    National parks are also in disarray, with few rangers to control crowds or enforce sanitation rules or regulations against environmental damage. Visitors wanting to drive off-road through the California desert cut down protected Joshua trees to clear a path in Joshua Tree National Park, park superintendent David Smith told National Parks Traveler. It can take years for desert soils and slow-growing Joshua trees to recover from such damage.

    PARK PLUNDERED National parks have remained open during the partial shutdown. But with only a few rangers on duty, visitors have caused long-term damage to some, such as Joshua Tree National Park in California, where trees have been cut down for off-roading. Frank DeBonis/iStock.com

    Information access

    Scientists aren’t able to gather data from government websites that are not being updated or are now offline. That’s hurt climate scientist Angeline Pendergrass’ work building computer models at the National Center for Atmospheric Research in Boulder, Colorado, to predict how climate change will impact rainfall patterns.

    Pendergrass normally verifies her calculations against precipitation records housed in the Global Historical Climatology Network, which logs global temperature and rainfall measurements. But while those data are still being collected automatically, the data aren’t available as usual through NOAA. Pendergrass’ project was stalled for days until she found a workaround to access the data in a different way.

    “I worry a lot about missing observations” from monitoring equipment malfunctions, Pendergrass says, which could mess up her research.

    Her concerns are well-founded. About 10 percent of contributing U.S. weather stations appear to be offline, lead scientist Robert Rohde at Berkeley Earth, an independent group for scientific analysis based in Berkeley, Calif., tweeted. And data from “a large number of foreign stations are also not being merged into the archive,” he wrote.

    Animals in USDA facilities are still being cared for, but scientists can’t collect data or do experiments. Interruptions in animal research involving steps being taken at certain times — like cows that need to be bred at a certain age — can set researchers back months or even years.

    Scientific collaboration

    During the shutdown, federal scientists can’t attend scientific meetings — important arenas for sharing new research. Already, government scientists have missed key conferences on astronomy, biology, weather and agricultural science.

    More than 10 percent of planned participants at the American Astronomical Society meeting that just wrapped up on January 10 in Seattle had to cancel presentations, AAS spokesman Rick Fienberg says. Some were able to ask coauthors to take their place; astrophysicist Jane Rigby at NASA’s Goddard Space Flight Center was not one of them.

    Rigby had to abandon her planned talks about the James Webb Space Telescope because nobody outside of the U.S. space agency had the expertise to cover for her. “This is the Super Bowl of astronomy, and we’re not allowed to play,” she says. “It’s not even like we’re benched. We’re not even allowed in the stadium.”

    Hundreds of USDA employees have also pulled out of the San Diego meeting of the International Plant & Animal Genome that starts January 12, says conference co-organizer Alison Van Eenennaam, an agricultural genomicist at the University of California, Davis.

    Because future research priorities are decided at such conferences, she says, the cancelations “will have implications for the whole year’s research.”

    One of Van Eenennaam’s graduate students relies on a USDA computer server to run a simulation program for research that’s needed to complete her degree. She isn’t allowed to access it right now, so the planned updates to make the program more suitable to the project’s needs also aren’t happening.

    “She’s stuck,” Van Eenennaam says.

    Timely research

    Some scientists can ride out any funding delays. But for those working on projects that are time sensitive, the halt in funding approvals threatens to throw off an entire year of work.

    Physiologist Hannah Carey is still waiting for this year’s money to come in for her research at the University of Wisconsin–Madison on ground squirrel hibernation. Because hibernating animals endure extreme changes in body temperature and heart rate, studying how they cope could help scientists understand how human bodies deal with trauma or extreme conditions.

    GOING DORMANT Hannah Carey of the University of Wisconsin–Madison studies hibernation in ground squirrels. But because of the shutdown, her grant money for the year hasn’t arrived yet. Rob Streiffer

    See the full article here .


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  • richardmitnick 1:18 pm on December 13, 2018 Permalink | Reply
    Tags: Science News, , The Parker Solar Probe takes its first up-close look at the sun   

    From Science News: “The Parker Solar Probe takes its first up-close look at the sun” 

    From Science News

    December 12, 2018
    Lisa Grossman

    NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker

    The spacecraft broke speed and distance records on its initial solar flyby.

    FIRST LOOK One of the first images NASA’s Parker Solar Probe took during its close encounter with the sun shows a streamer of plasma in the outer solar atmosphere, or corona. The probe took this image November 8 at a distance of about 27 million kilometers from the sun’s surface. The bright dot below the streamer is Jupiter. Parker Solar Probe/NASA and Naval Research Laboratory

    NASA’s Parker Solar Probe has met the sun and lived to tell the tale.

    The sun-grazing spacecraft has already broken the records for the fastest space probe and the nearest brush any spacecraft has made with the sun. Now the probe is sending data back from its close solar encounter, scientists reported December 12 at the American Geophysical Union meeting in Washington, D.C.

    “What we are looking at now is completely brand new,” solar physicist Nour Raouafi of Johns Hopkins University Applied Physics Lab in Laurel, Md., said at a news conference. “Nobody looked at this before.”

    Parker launched August 12 (SN Online: 8/12/18) and will make 24 close passes by the sun over the next seven years, eventually going to within about 6 million kilometers of the sun’s surface (SN: 7/21/18, p. 12). The spacecraft made its first close flyby November 6, swooping to within roughly 24 million kilometers of the solar surface. That’s about twice as close to the sun as the previous closest spacecraft, the Helios spacecraft in the 1970s. At peak speed, Parker was racing at about 375,000 kilometers per hour, roughly twice Helios’ speed.

    But because the probe was on the opposite side of the sun from Earth during the flyby, Parker didn’t start relaying its observations until December 7.

    After the probe emerged from behind the sun, the Parker team got its first up-close look at the wispy outer solar atmosphere, called the corona. One of the first images from Parker’s camera shows unprecedented detail in a solar streamer, a filament of plasma in the corona. The team hopes that Parker’s data will help solve the mystery of why the corona is about 300 times as hot as the sun’s surface (SN Online: 8/20/17).

    Only about one-fifth of the data recorded during Parker’s initial flyby will reach scientists before the sun gets between Earth and the spacecraft again. The rest of the data will be downlinked next year, between March and May. Scientists hope to start publishing results soon after.

    “If you ask any scientist in the team or even outside what to expect, I think the answer would be, we don’t really know,” Raouafi said. “We are almost certain we’ll make new discoveries.”

    See the full article here .


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  • richardmitnick 10:45 am on December 6, 2018 Permalink | Reply
    Tags: , , , , , , , NASA/ESA Cosmic Origins Spectrograph, Science News, The ecosystem that controls a galaxy’s future is coming into focus   

    From Science News: “The ecosystem that controls a galaxy’s future is coming into focus” 

    From Science News

    July 12, 2018
    Lisa Grossman

    The circumgalactic medium has been hard to observe, but new tools now make it possible.

    COSMIC CLOAK Whirls of cold and hot gas billow in this simulation of a circumgalactic medium surrounding a galaxy. With new tools and simulations, researchers have learned that the CGM helps a galaxy recycle its materials. M.S. Peeples et al/FOGGIE Project

    There’s more to a galaxy than meets the eye. Galaxies’ bright stars seem to spiral serenely against the dark backdrop of space. But a more careful look reveals a whole lot of mayhem.

    “Galaxies are just like you and me,” Jessica Werk, an astronomer at the University of Washington in Seattle, said in January at a meeting of the American Astronomical Society. “They live their lives in a constant state of turmoil.”

    Much of that turmoil takes place in a huge, complicated setting called the circumgalactic medium, or CGM. This vast, roiling cloud of dust and gas is a galaxy’s fuel source, waste dump and recycling center all in one [Annual Review of Astronomy and Astrophysics]. Astronomers think the answers to some of the most pressing galactic mysteries — how galaxies keep forming new stars for billions of years, why star formation abruptly stops — are hidden in a galaxy’s enveloping CGM.

    “To understand the galaxies, you have to understand the ecosystem that they’re in,” says astronomer Molly Peeples of the Space Telescope Science Institute in Baltimore.

    Yet this galactic atmosphere is so diffuse that it’s invisible — a liter of CGM contains just a single atom. It has taken almost 60 years and an upgrade to the Hubble Space Telescope just to begin probing distant CGMs and figuring out how their constant churning can make or break galaxies.

    “Only recently have we been able to really, truly, observationally characterize the relationship between this gaseous cycle and the properties of the galaxy itself,” Werk says.

    Armed with the first extragalactic census, astronomers are now piecing together how a CGM controls its galaxy’s life and death. And new theoretical studies hint that galaxies’ stars would be arranged very differently without a medium’s frenetic flows. Plus, new observations show that some CGMs are surprisingly lumpy [Nature]. A better understanding of CGMs, enabled by new telescopes and computer simulations, could change how scientists think about everything from galaxy collisions to the origins of our own atoms.

    “The CGM is the part of the iceberg that’s under the water,” says astrophysicist Kevin Schawinski of ETH Zurich, who studies the more conventional parts of galaxies. “We now have good measurements where we’re sure it’s important.”

    Frenetic fog

    Researchers use a bright source of background light, like a quasar, to learn about a galaxy’s circumgalactic medium, a diffuse cloud of gas and metals (pink in the illustration) surrounding a galaxy. Gas is recycled between the galaxy and the CGM.

    Sources: J. Tumlinson, M.S. Peeples and J.K. Werk/Annual Review of Astronomy and Astrophysics 2017; M.S. Peeples/Nature 2015

    Waiting for Hubble

    That 2009 Hubble telescope upgrade, which made the CGM census possible, almost didn’t happen.

    In a cosmic coincidence, the Hubble telescope’s chief champions were also the first astronomers to figure out how to observe a galaxy’s CGM. Lyman Spitzer of Princeton University and John Bahcall of the Institute for Advanced Study in Princeton, N.J., and other astronomers noticed something strange after the 1963 discovery of quasars [http://cosmology.carnegiescience.edu/timeline/1963] (SN Online: 3/21/14), bright beacons now known to be white-hot disks surrounding supermassive black holes in the centers of distant galaxies.

    Everywhere astronomers looked, quasars’ spectra — the rainbow created when their light is spread out over all wavelengths — were notched with dark holes. Some wavelengths of light weren’t getting through.

    In 1969, Spitzer and Bahcall realized what was going on: The missing light was absorbed by gas at the edges of galaxies, the same stuff that would later be called the CGM. Astronomers had been peering at quasars shining through CGMs like headlights through a fog.

    Not much more could be done at the time, though. Earth’s atmosphere also absorbs light in those same wavelengths, making it difficult to tell which light-blocking atoms were in a galaxy’s CGM and which came from closer to home. Knowing that a CGM was there was one thing; taking its measurements would require something extra.

    Spitzer and Bahcall knew what they needed: a space telescope that could observe from outside Earth’s atmosphere. The pair were two of the most vocal and consistent champions of the Hubble Space Telescope, which launched in 1990. Spitzer’s colleagues called him Hubble’s “intellectual and political father.”

    Bahcall never stopped advocating for Hubble. In February 2005, six months before his death at age 70 from a rare blood disorder, he co-wrote an article in the Los Angeles Times [http://articles.latimes.com/2005/feb/23/opinion/oe-tayloretal23] urging Congress to restore funding for a mission to fix some aging Hubble instruments, which NASA had canceled after the 2003 Columbia space shuttle disaster.

    “What is at stake is not only a piece of stellar technology but our commitment to the most fundamental human quest: understanding the cosmos,” Bahcall and colleagues wrote. “Hubble’s most important discoveries could be in the future.”

    His plea was answered: The space shuttle Atlantis brought astronauts to repair Hubble for the last time in May 2009 (SN Online: 5/19/09). During the repair, the astronauts installed the Cosmic Origins Spectrograph, which could pick up diffuse CGM gas with 30 times the sensitivity of any previous instrument.

    NASA Hubble Cosmic Origins Spectrograph

    Although earlier spectrographs on Hubble had picked out CGMs a few quasar-beams at a time, the new device let astronomers search around dozens of galaxies, using the light of even dimmer quasars.

    “It blew the field wide open,” Werk says.

    Gas flows out from Messier 82, the Cigar galaxy, to its invisible circumgalactic medium in this Hubble image. NASA, ESA, Hubble Heritage Team

    The circumgalactic census

    A team led by Jason Tumlinson of Baltimore’s Space Telescope Science Institute, Hubble’s academic home, made a catalog of 44 galaxies with a quasar sitting behind them from Hubble’s perspective. In a 2011 paper in Science, the researchers reported that every time they looked within 490,000 light-years of a galaxy, they saw spectra dappled with blank spots from atoms absorbing light. That meant that CGMs weren’t odd cloaks worn by just a few galaxies. They were everywhere.

    Tumlinson’s team spent the first few years after Hubble’s upgrade like 19th century naturalists describing new species. The group measured the mass and the chemical makeup of the galaxies’ CGMs and found they were huge cisterns of heavy elements. CGMs contain 10 million times the mass of the sun in oxygen alone. In many cases, the mass of a CGM is comparable to the mass of the entire visible part of its galaxy.

    The finding offers an answer to a long-standing cosmic mystery: How do galaxies have enough star-forming fuel to keep going for billions of years? Galaxies build stars from collapsing clouds of cool gas at a constant rate; the Milky Way, for example, makes one to two solar masses’ worth of stars every year. But there isn’t enough cool gas within the visible part of a galaxy, the disk containing its stars, to support observed rates of star formation.

    “We think that gas probably comes from the CGM,” Werk says. “But exactly how that gas is getting into galaxies, where it gets in, the timescale on which it gets in, are there things that prevent it from getting in? Those are big questions that keep us all awake at night.”

    Werk and Peeples realized that all that mass could help solve two other cosmic bookkeeping problems. All elements heavier than helium (which astronomers lump together as “metals”) are forged by nuclear fusion in the hearts of stars. When stars use up their fuel and explode as supernovas, they scatter those metals around to be folded into the next generation of stars.

    But if you add up all the metals in the stars, gas and dust in a given galaxy’s disk, it’s not enough to account for all the metals the galaxy has ever made. The mismatch gets even worse if you include the hydrogen, helium, electrons and protons — basically all the ordinary matter that should have collected in the galaxy since the Big Bang. Astronomers call all those bits baryons. Galaxies seem to be missing 70 to 95 percent of that stuff.

    So Peeples and Werk led a comprehensive effort to tally all the ordinary matter in about 40 galaxies observed with Hubble’s new spectrometer. The researchers published the results in two 2014 papers in The Astrophysical Journal.

    At the time, Werk reported that at least half of galaxies’ missing ordinary matter can be accounted for in their CGMs. In a 2017 update, Werk and colleagues found that the mass of baryons just in the form of cool gas in a galaxy’s CGM could be nearly 90 billion solar masses [The Astrophysical Journal]. “Obviously, this mass could resolve the galactic missing baryons problem,” the team wrote.

    “It’s a classic science story,” Schawinski says. The researchers had a hypothesis about where the missing material should be and made predictions. The group made observations to test those predictions and found what it sought.

    In a separate study, Peeples showed that although metals are born in galaxies’ starry disks, those metals don’t stay there. Only 20 to 25 percent of the metals a galaxy has ever produced remains in the stars, gas and dust in the disk, where the metals can be incorporated into new stars and planets. The rest probably ends up in the CGM.

    “If you look at all the metals the galaxies ever produced in their whole lifetime, more of them are outside the galaxy than are still inside the galaxy,” Tumlinson says, “which was a huge shock.”

    Recycling centers

    So how did the metals get into the CGM? Quasars’ spectra couldn’t help with that question. Their light shows only a slice through a single galaxy at a single moment in time. But astronomers can track galaxies’ growth and development with computer simulations based on physical rules for how stars and gas behave.

    This strategy revealed the churning, ever-changing nature of gas in galaxies’ CGMs. Simulations such as EAGLE, or Evolution and Assembly of GaLaxies and their Environments, which is run out of Leiden University in the Netherlands, showed that metals can reach CGMs through stars’ violent lives: in powerful winds of radiation blowing away from massive young stars, and in the death throes of supernovas spraying metals far and wide.

    This EAGLE simulation shows that, over time, metals (colors) move away from the center of a galaxy to the circumgalactic medium. J. Tumlinson, M.S. Peeples and J.K. Werk/Annual Review of Astronomy and Astrophysics 2017

    Once the metals are in the CGM, though, they don’t always stay put. In simulations, galaxies seem to use the same gas over and over again.

    “It’s basically just gravity,” Peeples says. “Throw a baseball up, and it’ll come back to the ground.” The same goes for gas flowing out of galaxies: Unless the gas travels fast enough to escape the galaxy’s gravity altogether, those atoms will eventually fall back into the disk — and form new stars.

    Some simulations show discrete gas parcels making the trip from a galaxy’s disk out into the CGM and back again several times. Together, CGMs and their galaxies are giant recycling devices.

    That means that the atoms that make up planets, plants and people may have taken several trips to circumgalactic space before becoming part of us. Over hundreds of millions of years, the atoms that eventually became part of you traveled hundreds of thousands of light-years.

    “This is my favorite thing,” Tumlinson says. “At some point, your carbon, your oxygen, your nitrogen, your iron was out in intergalactic space.”

    How galaxies die

    But not all galaxies get their CGM gas back. Losing the gas could shut off star formation in a galaxy for good. No one knows how star formation shuts off, or quenches. But the answer is probably in the CGM.

    Galaxies come in two main forms: young spiral galaxies that are making stars and old blobby galaxies where star formation is quenched (SN Online: 4/23/18).

    “How galaxies quench and why they stay that way is one of the most important questions in galaxy formation generally,” Tumlinson says. “It just has to have something to do with the gas supply.”

    Reading what’s not there

    Using light from a quasar (QSO), researchers can “see” CGMs. In this example, spectra from two galaxies, G1 and G2, have certain wavelengths missing (red, in bottom boxes) where the CGM atoms are absorbing light.


    One possibility, suggested in a paper posted online February 20 in The Astrophysical Journal, is that sprays of supernova-heated gas could get stripped from galaxies. Physicist Chad Bustard of the University of Wisconsin–Madison and colleagues simulated the Large Magellanic Cloud, a satellite galaxy of the Milky Way, and found that the small galaxy’s outflowing gas was swept away by the slight pressure of the galaxy’s movement around the Milky Way.

    Alternatively, a dead galaxy’s CGM gas could be too hot to sink into the galaxy and form stars. If so, star-forming galaxies should have CGMs full of cold gas, and dead galaxies should be shrouded in hot gas. Hot gas would stay floating above the galactic disk like a hot air balloon, too buoyant to sink in and form stars.

    But Hubble saw the opposite. Star-forming galaxies had CGMs chock-full of oxygen-VI — meaning that the gas was so hot (a million degrees Celsius or more) that oxygen atoms lost five of their original electrons. Dead galaxies had surprisingly little oxygen-VI.

    “That was puzzling,” Tumlinson says. “If theory told us anything, it should have gone the other way.”

    In 2016, Benjamin Oppenheimer, a computational astrophysicist at the University of Colorado Boulder, suggested a solution: The “dead” galaxies didn’t lack oxygen at all. The gas was just too hot for Hubble to observe. “In fact, there is even more oxygen around those passive galaxies,” Oppenheimer says.

    All that hot gas could potentially explain why those galaxies died — except that these galaxies were full of star-forming cold gas, too.

    “The dead galaxies have plenty of fuel left in the tank,” Tumlinson says. “We don’t know why they’re not using it. Everybody’s chasing that problem.”

    Grabbing at the elephant

    The chase comes at a good time. Until recently, observers had no way to map a single galaxy’s CGM. Researchers have had to add up dozens of quasar beams to understand the composition of CGMs on average.

    “We’ve been like the three blind people grabbing at the elephant,” says John O’Meara, an observational astronomer at Saint Michael’s College in Colchester, Vt.

    Teams using two new spectrographs — KCWI, the Keck Cosmic Web Imager on the Keck telescope in Hawaii, and MUSE, the Multi Unit Spectroscopic Explorer on the Very Large Telescope in Chile — are racing to change that.

    Keck Cosmic Web Imager schematic

    Keck Cosmic Web Imager

    Keck Observatory, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level,

    ESO MUSE on the VLT on Yepun (UT4),

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo

    These instruments, called integral field spectrographs, can read spectra across a full galaxy all at once. Given enough background light, astronomers can now examine a single galaxy’s entire CGM. Finally, astronomers have a way to test theories of how gas circulates into and out of a galaxy.

    A Chilean team, led by astronomer Sebastian Lopez of the University of Chile in Santiago and colleagues, used MUSE to observe a small dim galaxy that happens to be sandwiched between a bright, distant galaxy and a massive galaxy cluster closer to Earth. The cluster acts as a gravitational lens, distorting the image of the distant galaxy into a long bright arc (SN: 3/10/12, p. 4). The light from that arc filtered through the CGM of the sandwiched galaxy, which the team called G1, at 56 different points.

    Surprisingly, G1’s CGM was lumpy, not smooth as expected, the team reported in the Feb. 22 Nature. “The assumption has been that that gas is distributed homogeneously around every system,” Lopez says. “This is not the case.”

    MUSE makes a mark

    Light from a source galaxy is deflected and magnified by an intervening galaxy cluster to form the bright arc seen in the projected image at far right. Unlike a quasar’s narrow beam of light, the extensive arc lights up a large area of galaxy G1’s CGM, showing it is surprisingly lumpy.


    O’Meara is leading a group that is hot on Lopez’s trail. Last year, while KCWI was being installed, O’Meara got an hour of observing time and was able to see hydrogen — which is associated with cool, star-forming gas — in the CGM of another galaxy backlit by a bright lensed arc. He’s not ready to discuss the results in detail yet, but the team is submitting a paper to Science.

    Meanwhile, Peeples’ team is revisiting how computers render CGMs. “The resolution of the circumgalactic medium in simulations is, um, bad,” she says. Existing simulations are good at matching the visible properties of galaxies — their stars, the gas between the stars, and the overall shapes and sizes. But they “utterly fail at reproducing the properties of the circumgalactic medium,” she says.

    So she’s running a new set of simulations called FOGGIE, which focus on CGMs for the first time. “We’re finding that it changes everything,” she says: The shape, star formation history and even the orientation of the galaxy in space look different.

    Together, the new observations and simulations suggest that the CGM’s function in the life cycle of a galaxy has been underestimated. Theorists like Peeples and observers like O’Meara are working together to make new predictions about how the CGM should look. Then the researchers will check real galaxies to see if they match.

    “Molly will post a really amazing new render of a simulation on Slack, and I’ll go, ‘Holy crap, that looks weird!’ ” O’Meara says. “I’ll go scampering off to find a similar example in the data, and we get into this positive feedback loop of going ‘Holy crap! Holy crap!’ ”

    While future circumgalactic studies will focus on gathering spectra from full CGMs, Tumlinson is hoping to squeeze more information out of Hubble while he still can. Hubble made CGM studies possible, but the telescope is 28 years old, and probably has less than a decade left. Hubble’s spectrograph is still the best at observing certain atoms in CGMs to help reveal the gaseous halos’ secrets. “It’s something we definitely want to do,” he says, “before Hubble ends up in the ocean.”

    See the full article here .


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  • richardmitnick 9:42 am on December 2, 2018 Permalink | Reply
    Tags: , , Physicists finally calculated where the proton’s mass comes from, Science News   

    From Science News: “Physicists finally calculated where the proton’s mass comes from” 

    From Science News

    November 26, 2018
    Emily Conover

    Only 9 percent of the subatomic particle’s bulk comes from the mass of its quarks.

    MASSIVE UNDERTAKING Using a technique called lattice QCD, scientists figured out how protons (illustrated here in the nucleus of an atom) get their mass.

    A proton’s mass is more than just the sum of its parts. And now scientists know just what accounts for the subatomic particle’s heft.

    Protons are made up of even smaller particles called quarks, so you might expect that simply adding up the quarks’ masses should give you the proton’s mass. However, that sum is much too small to explain the proton’s bulk. And new, detailed calculations show that only 9 percent of the proton’s heft comes from the mass of constituent quarks. The rest of the proton’s mass comes from complicated effects occurring inside the particle, researchers report in the Nov. 23 Physical Review Letters.

    Quarks get their masses from a process connected to the Higgs boson, an elementary particle first detected in 2012 (SN: 7/28/12, p. 5). But “the quark masses are tiny,” says study coauthor and theoretical physicist Keh-Fei Liu of the University of Kentucky in Lexington. So, for protons, the Higgs explanation falls short.

    Instead, most of the proton’s 938 million electron volts of mass is due to complexities of quantum chromodynamics, or QCD, the theory which accounts for the churning of particles within the proton. Making calculations with QCD is extremely difficult, so to study the proton’s properties theoretically, scientists rely on a technique called lattice QCD, in which space and time are broken up into a grid, upon which the quarks reside.

    Using this technique, physicists had previously calculated the proton’s mass (SN: 12/20/08, p. 13). But scientists hadn’t divvied up where that mass comes from until now, says theoretical physicist André Walker-Loud of Lawrence Berkeley National Laboratory in California. “It’s exciting because it’s a sign that … we’ve really hit this new era” in which lattice QCD can be used to better understand nuclear physics.

    In addition to the 9 percent of the proton’s mass that comes from quarks’ heft, 32 percent comes from the energy of the quarks zipping around inside the proton, Liu and colleagues found. (That’s because energy and mass are two sides of the same coin, thanks to Einstein’s famous equation, E=mc2.) Other occupants of the proton, massless particles called gluons that help hold quarks together, contribute another 36 percent via their energy.

    The remaining 23 percent arises due to quantum effects that occur when quarks and gluons interact in complicated ways within the proton. Those interactions cause QCD to flout a principle called scale invariance. In scale invariant theories, stretching or shrinking space and time makes no difference to the theories’ results. Massive particles provide the theory with a scale, so when QCD defies scale invariance, protons also gain mass.

    The results of the study aren’t surprising, says theoretical physicist Andreas Kronfeld of Fermilab in Batavia, Ill. Scientists have long suspected that the proton’s mass was made up in this way. But, he says, “this kind of calculation replaces a belief with scientific knowledge.”

    See the full article here .


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  • richardmitnick 12:16 pm on November 23, 2018 Permalink | Reply
    Tags: A low-altitude meteor explosion around 3700 years ago destroyed cities villages and farmland north of the Dead Sea rendering the region uninhabitable for 600 to 700 years, An exploding meteor may have wiped out ancient Dead Sea communities, , , Science News   

    From Science News: “An exploding meteor may have wiped out ancient Dead Sea communities” 

    From Science News

    November 20, 2018
    Bruce Bower

    Archaeologists at a site in what’s now Jordan have found evidence of a cosmic calamity.

    ANCIENT WIPEOUT Preliminary evidence indicates that a low-altitude meteor explosion around 3,700 years ago destroyed cities, villages and farmland north of the Dead Sea (shown in the background above) rendering the region uninhabitable for 600 to 700 years.

    A superheated blast from the skies obliterated cities and farming settlements north of the Dead Sea around 3,700 years ago, preliminary findings suggest.

    Radiocarbon dating and unearthed minerals that instantly crystallized at high temperatures indicate that a massive airburst caused by a meteor that exploded in the atmosphere instantaneously destroyed civilization in a 25-kilometer-wide circular plain called Middle Ghor, said archaeologist Phillip Silvia. The event also pushed a bubbling brine of Dead Sea salts over once-fertile farm land, Silvia and his colleagues suspect.

    People did not return to the region for 600 to 700 years, said Silvia, of Trinity Southwest University in Albuquerque. He reported these findings at the annual meeting of the American Schools of Oriental Research on November 17.

    Excavations at five large Middle Ghor sites, in what’s now Jordan, indicate that all were continuously occupied for at least 2,500 years until a sudden, collective collapse toward the end of the Bronze Age. Ground surveys have located 120 additional, smaller settlements in the region that the researchers suspect were also exposed to extreme, collapse-inducing heat and wind. An estimated 40,000 to 65,000 people inhabited Middle Ghor when the cosmic calamity hit, Silvia said.

    The most comprehensive evidence of destruction caused by a low-altitude meteor explosion comes from the Bronze Age city of Tall el-Hammam, where a team that includes Silvia has been excavating for the last 13 years. Radiocarbon dating indicates that the mud-brick walls of nearly all structures suddenly disappeared around 3,700 years ago, leaving only stone foundations.

    What’s more, the outer layers of many pieces of pottery from same time period show signs of having melted into glass. Zircon crystals in those glassy coats formed within one second at extremely high temperatures, perhaps as hot as the surface of the sun, Silvia said.

    High-force winds created tiny, spherical mineral grains that apparently rained down on Tall el-Hammam, he said. The research team has identified these minuscule bits of rock on pottery fragments at the site.

    Examples exist of exploding space rocks that have wreaked havoc on Earth (SN: 5/13/17, p. 12). An apparent meteor blast over a sparsely populated Siberian region in 1908, known as the Tunguska event, killed no one but flattened 2,000 square kilometers of forest. And a meteor explosion over Chelyabinsk, Russia, in 2013 injured more than 1,600 people, mainly due to broken glass from windows that were blown out.

    See the full article here .


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  • richardmitnick 3:19 pm on November 11, 2018 Permalink | Reply
    Tags: , , , , Hints of Oort clouds around other stars may lurk in the universe’s first light, Science News   

    From Science News: “Hints of Oort clouds around other stars may lurk in the universe’s first light” 

    From Science News

    November 9, 2018
    Lisa Grossman

    Searching the cosmic microwave background could reveal other giant spheres of icy debris.

    HIDDEN TREASURES This map of the cosmic microwave background taken by the Planck satellite could also hide signs of exo-Oort clouds — planetary graveyards surrounding other stars.

    A thick sphere of icy debris known as the Oort cloud shrouds the solar system. Other star systems may harbor similar icy reservoirs, and those clouds may be visible in the universe’s oldest light, researchers report.

    Oort Cloud, The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA, Universe Today

    Astronomer Eric Baxter of the University of Pennsylvania and colleagues looked for evidence of such exo-Oort clouds in maps of the cosmic microwave background, the cool cosmic glow of the first light released after the Big Bang, roughly 13.8 billion years ago. No exo-Oort clouds have been spotted yet, but the technique looks promising, the team reports November 2 in The Astronomical Journal. Finding exo-Oort clouds could help shed light on how other solar systems — and perhaps even our own — formed and evolved.

    The Oort cloud is thought to be a planetary graveyard stretching between about 1,000 and 100,000 times as far from the sun as Earth. Scientist think that this reservoir of trillions of icy objects formed early in the solar system’s history, when violent movements of the giant planets as they took shape tossed smaller objects outward. Every so often, one of those frozen planetary fossils dives back in toward the sun and is visible as a comet (SN: 11/16/13, p. 14).

    But it’s difficult to observe the Oort cloud directly from within it. Despite a lot of circumstantial evidence for the Oort cloud’s existence, no one has ever seen it.

    Ironically, exo-Oort clouds might be easier to spot, Baxter and colleagues thought. The objects in an exo-Oort cloud wouldn’t reflect enough starlight to be seen directly, but they would absorb starlight and radiate it back out into space as heat. For the sun’s Oort cloud, that heat signal would be smeared evenly across the entire sky from Earth’s perspective. But an exo-Oort cloud’s warmth would be limited to a tiny region around its star.

    Baxter and colleagues calculated that the expected temperature of an exo-Oort cloud should be about –265° Celsius, or 10 kelvins. That’s right in range for experiments that detect the cosmic microwave background, or CMB, which is about 3 kelvins.

    The team used data from the CMB-mapping Planck satellite to search for areas across the sky with the right temperature (SN Online: 7/24/18).

    ESA/Planck 2009 to 2013

    Then, the researchers compared the results with the Gaia space telescope’s ultraprecise stellar map to see if those regions surrounded stars (SN: 5/26/18, p. 5).

    ESA/GAIA satellite

    ESA GAIA Release 2 map

    Although the astronomers found some intriguing signals around several bright, nearby stars, it wasn’t enough to declare victory. “That’s pretty interesting, but we can’t definitively say that it’s from an Oort cloud or not,” Baxter says.

    Other ongoing CMB experiments with higher resolution, like those with the South Pole Telescope and the Atacama Cosmology Telescope in the Chilean Andes, could confirm if those hints of exo-Oort clouds are real.

    South Pole Telescope SPTPOL. The SPT collaboration is made up of over a dozen (mostly North American) institutions, including the University of Chicago, the University of California, Berkeley, Case Western Reserve University, Harvard/Smithsonian Astrophysical Observatory, the University of Colorado Boulder, McGill University, The University of Illinois at Urbana-Champaign, University of California, Davis, Ludwig Maximilian University of Munich, Argonne National Laboratory, and the National Institute for Standards and Technology. It is funded by the National Science Foundation.


    “It’s a super clever observational idea,” says astronomer Nicolas Cowan of McGill University in Montreal who was not involved in the new work. “Looking for exo-Oort clouds is looking for a signature of these violent histories in other solar systems.”

    Cowan has suggested that the cosmic microwave background could also be used to search for a hypothetical Planet Nine in the sun’s Oort cloud (SN: 7/23/16, p. 7). “The very coolest thing would be if we could get measurements of the exo-Oort clouds and find planets in those systems,” he says.

    See the full article here .


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  • richardmitnick 12:07 pm on November 8, 2018 Permalink | Reply
    Tags: , , Science News, Weyl metals might reveal the secrets of how Earth gets its magnetic field   

    From Science News: “Bizarre metals may help unlock mysteries of how Earth’s magnetic field forms” 

    From Science News

    November 7, 2018
    Emily Conover

    The dynamo effect that generates Earth’s magnetic pull could also occur in Weyl metals.

    MAKING MAGNETISM Earth’s magnetic field (illustrated) as well as those of stars and other astronomical objects are created by flows of electrically conductive substances. On smaller scales, such dynamos may also be created by materials called Weyl metals. Goddard Space Flight Center/NASA.

    Weird materials called Weyl metals might reveal the secrets of how Earth gets its magnetic field.

    The substances could generate a dynamo effect, the process by which a swirling, electrically conductive material creates a magnetic field, a team of scientists reports in the Oct. 26 Physical Review Letters.

    Dynamos are common in the universe, producing the magnetic fields of the Earth, the sun and other stars and galaxies. But scientists still don’t fully understand the details of how dynamos create magnetic fields. And, unfortunately, making a dynamo in the lab is no easy task, requiring researchers to rapidly spin giant tanks of a liquefied metal, such as sodium (SN: 5/18/13, p. 26).

    First discovered in 2015, Weyl metals are topological materials, meaning that their behavior is governed by a branch of mathematics called topology, the study of shapes like doughnuts and knots (SN: 8/22/15, p. 11). Electrons in Weyl metals move around in bizarre ways, behaving as if they are massless.

    Within these materials, the researchers discovered, electrons are subject to the same set of equations that describes the behavior of liquids known to form dynamos, such as molten iron in the Earth’s outer core. The team’s calculations suggest that, under the right conditions, it should be possible to make a dynamo from solid Weyl metals.

    It might be easier to create such dynamos in the lab, as they don’t require large quantities of swirling liquid metals. Instead, the electrons in a small chunk of Weyl metal could flow like a fluid, taking the place of the liquid metal.

    The result is still theoretical. But if the idea works, scientists may be able to use Weyl metals to reproduce the conditions that exist within the Earth, and better understand how its magnetic field forms.

    See the full article here .


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