Tagged: SciNews Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 8:56 am on March 17, 2019 Permalink | Reply
    Tags: A single ion of ytterbium, , , Einstein’s special theory of relativity, SciNews   

    From Science News: “Ultraprecise atomic clocks put Einstein’s special relativity to the test” 

    From Science News

    March 13, 2019
    Emily Conover

    An experiment tested a foundational principle of physics known as Lorentz symmetry.

    1
    WATCHING THE CLOCK Scientists monitored two atomic clocks for six months in order to test a tenet of Einstein’s special theory of relativity. Each clock, like the one shown, contained a single ion of ytterbium. PTB

    The ticktock of two ultraprecise clocks has proven Einstein right, once again.

    A pair of atomic clocks made of single ions of ytterbium kept pace with one another over six months, scientists report March 13 in Nature. The timepieces’ reliability supports a principle known as Lorentz symmetry. That principle was the foundation for Einstein’s special theory of relativity, which describes the physics of voyagers dashing along at nearly the speed of light.

    Lorentz symmetry states that the rules of physics should remain the same whether you’re standing still or moving at a breakneck speed, and no matter what direction you’re facing (SN: 7/8/17, p. 14). The clocks kept up with one another as the Earth rotated, confirming that idea.

    The two ytterbium ions — positively charged atoms — absorbed and emitted light at a particular frequency, functioning like the ticking of a clock hand. The ions, which were oriented in different directions, rotated as the Earth turned, making a full cycle each day. If the atomic clocks’ ticks varied based on their orientation in space, the experiment would reveal a daily variation in the relative frequencies from the two clocks — a violation of Lorentz symmetry. But the atomic clocks agreed within about a tenth of a quadrillionth of a percent, confirming with about 100 times the precision of previous tests that Lorentz symmetry held.

    Although Lorentz symmetry has been confirmed repeatedly, some scientists predict that it won’t hold up to increasingly precise tests. Some theories of quantum gravity, which aim to unite scientists’ understanding of gravity with the theory of very small objects (SN: 10/17/15, p. 28), suggest that Lorentz symmetry’s days are numbered. But so far, there’s no hint of its demise.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 10:45 am on August 30, 2018 Permalink | Reply
    Tags: Gravity measured to new precision, Measuring G. with two slightly different torsion pendulum set ups as described in the article had slightly different results, Pinpointing Big G could help refine mass measurements for Earth and other celestial objects, SciNews, So- the true value of G “is still a mystery   

    From Science News: “The strength of gravity has been measured to new precision” 

    From Science News

    August 29, 2018
    Maria Temming

    Pinpointing Big G could help refine mass measurements for Earth and other celestial objects.

    1
    HOMING IN Gravity (illustrated here bending spacetime) has been notoriously hard to measure. Now two new lab experiments estimate the strength of gravity, or Big G, with record precision. Credit: vchal/Shutterstock

    We now have the most precise estimates for the strength of gravity yet.

    Two experiments measuring the tiny gravitational attraction between objects in a lab have measured Newton’s gravitational constant, or Big G, with an uncertainty of only about 0.00116 percent. Until now, the smallest margin of uncertainty for any G measurement has been 0.00137 percent.

    The new set of G values, reported in the Aug. 30 Nature, is not the final word on G. The two values disagree slightly, and they don’t explain why previous G-measuring experiments have produced such a wide spread of estimates (SN Online: 4/30/15). Still, researchers may be able to use the new values, along with other estimates of G, to discover why measurements for this key fundamental constant are so finicky — and perhaps pin down the strength of gravity once and for all.

    The exact value of G, which relates mass and distance to the force of gravity in Newton’s law of universal gravitation, has eluded scientists for centuries. That’s because the gravitational attraction between a pair of objects in a lab experiment is extremely small and susceptible to the gravitational influence of other nearby objects, often leaving researchers with high uncertainty about their measurements.

    ______________________________________________
    Weighing in

    Two new measurements for the strength of gravity (red squares, with short error bars indicating uncertainty) fall close to or within the currently accepted range for Big G (shaded gray). The new estimates are much more precise than those from other experiments in the last 40 years (teal dots and longer error bars).

    2
    S. Schlamminger/Nature 2018

    ______________________________________________

    The current accepted value for G, based on measurements from the last 40 years, is 6.67408 × 10−11 meters cubed per kilogram per square second. That figure is saddled with an uncertainty of 0.0047 percent, making it thousands of times more imprecise than other fundamental constants — unchanging, universal values such as the charge of an electron or the speed of light (SN: 11/12/16, p. 24). The cloud of uncertainty surrounding G limits how well researchers can determine the masses of celestial objects and the values of other constants that are based on G (SN: 4/23/11, p. 28).

    Physicist Shan-Qing Yang of Huazhong University of Science and Technology in Wuhan, China, and colleagues measured G using two instruments called torsion pendulums. Each device contains a metal-coated silica plate suspended by a thin wire and surrounded by steel spheres. The gravitational attraction between the plate and the spheres causes the plate to rotate on the wire toward the spheres.

    But the two torsion pendulums had slightly differently setups to accommodate two ways of measuring G. With one torsion pendulum, the researchers measured G by monitoring the twist of the wire as the plate angled itself toward the spheres. The other torsion pendulum was rigged so that the metal plate dangled from a turntable, which spun to prevent the wire from twisting. With that torsion pendulum, the researchers measured G by tracking the turntable’s rotation.

    To make their measurements as precise as possible, the researchers corrected for a long list of tiny disturbances, from slight variations in the density of materials used to make the torsion pendulums to seismic vibrations from earthquakes across the globe. “It’s amazing how much work went into this,” says Stephan Schlamminger, a physicist at the National Institute of Standards and Technology in Gaithersburg, Md., whose commentary on the study appears in the same issue of Nature. Conducting such a painstaking set of experiments “is like a piece of art.”commentary.Conducting such a painstaking set of experiments “is like a piece of art.”

    These torsion pendulum experiments yielded G values of 6.674184 × 10−11 and 6.674484 × 10−11 meters cubed per kilogram per square second, both with an uncertainty of about 0.00116 percent.

    This record precision is “a fantastic accomplishment,” says Clive Speake, a physicist at the University of Birmingham in England not involved in the work, but the true value of G “is still a mystery.” Repeating these and other past experiments to identify previously unknown sources of uncertainty, or designing new G–measuring techniques, may help reveal why estimates for this key fundamental constant continue to disagree, he says.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 8:21 am on August 26, 2018 Permalink | Reply
    Tags: , , , One photon emitted during the solar minimum had an energy as high as 467.7 GeV, SciNews, , Strange gamma rays from the sun may help decipher its magnetic fields, The high-energy light is more plentiful and weirder than anyone expected   

    From Science News: “Strange gamma rays from the sun may help decipher its magnetic fields” 

    From Science News

    August 24, 2018
    Lisa Grossman

    The high-energy light is more plentiful and weirder than anyone expected.

    1
    A TANGLED SKEIN The sun’s knotted magnetic fields, visualized here as white lines, scramble cosmic rays and may cause them to shoot energetic light called high-energy gamma rays toward Earth. Solar Dynamics Observatory/GSFC/NASA

    NASA/SDO

    The sleepy sun turns out to be a factory of extremely energetic light.

    Scientists have discovered that the sun puts out more of this light, called high-energy gamma rays, overall than predicted. But what’s really weird is that the rays with the highest energies appear when the star is supposed to be at its most sluggish, researchers report in an upcoming study in Physical Review Letters. The research is the first to examine these gamma rays over most of the solar cycle, a roughly 11-year period of waxing and waning solar activity.

    That newfound oddity is probably connected to the activity of the sun’s magnetic fields, the researchers say, and could lead to new insights about the mysterious environment.

    “The almost certain thing that’s going on here is the magnetic fields are much more powerful, much more variable, and much more weirdly shaped than we expect,” says astrophysicist John Beacom of the Ohio State University in Columbus.

    The sun’s high-energy gamma rays aren’t produced directly by the star. Instead, the light is triggered by cosmic rays — protons that zip through space with some of the highest energies known in nature — that smack into solar protons and produce high-energy gamma rays in the process (SN: 10/14/27, p. 7).

    All of those gamma rays would get lost inside the sun, if not for magnetic fields. Magnetic fields are known to take charged particles like cosmic rays and spin them around like a house in a tornado. Theorists have predicted that cosmic rays whose paths have been scrambled by the tangled mass of magnetic fields at the solar surface should send high-energy gamma rays shooting back out of the sun, where astronomers can see them.

    Beacom and colleagues, led by astrophysicist Tim Linden of Ohio State, sifted through data from NASA’s Fermi Gamma-ray Space Telescope from August 2008 to November 2017.

    NASA/Fermi LAT


    NASA/Fermi Gamma Ray Space Telescope

    The observations spanned a period of low solar activity in 2008 and 2009, a period of higher activity in 2013 and a decline in activity to the minimum of the next cycle, which started in 2018 (SN: 11/2/13, p. 22). The team tracked the number of solar gamma rays emitted per second, as well as their energies and where on the sun they came from.

    There were more high-energy gamma rays, above 50 billion electron volts, or GeV, than anyone predicted, the team reports. Weirder still, rays with energies above 100 GeV appeared only during the solar minimum, when the sun’s activity level was low. One photon emitted during the solar minimum had an energy as high as 467.7 GeV.

    Strangest of all, the sun seems to emit gamma rays from different parts of its surface at different times in its cycle. Because cosmic rays that hit the sun come in from all directions, you would expect the entire sun to light up in gamma rays uniformly. But Beacom’s team found that during the solar minimum, gamma rays came mainly from near the equator, and during the solar maximum, when the sun’s activity level was high, they clustered near the poles.

    “All of these things are way more weird than anyone had predicted,” Beacom says. “And that means the magnetic fields must be way more weird than anyone had thought.”
    ____________________________________________________
    The missing middle

    These plots show that the sun shot light called high-energy gamma rays from its middle during a period of low solar activity (from about August 2008 to the end of 2009, left), but not during a period of high activity (from 2010 until 2017, right). The gamma rays seem to migrate from the equator to the poles after 2010. Rays with less than 100 billion electron volts, or GeV, of energy are depicted as circles; those with 100 GeV or more are triangles. The bar graphs represent the number of gamma rays that came from different latitudes.

    3
    T. Linden et al/Physical Review Letters 2018
    ____________________________________________________

    Beacom and colleagues tried to connect the excess gamma rays to other solar behaviors that change with magnetic activity, like solar flares or sunspots (SN: 9/30/17, p. 6). “So far nothing has really held up to any sort of scrutiny,” says astrophysicist Annika Peter, also at Ohio State.

    High-energy gamma rays may offer a new way to probe the magnetic fields in the uppermost layer of the solar surface, called the photosphere. “You can’t see [the fields] with a telescope,” Beacom says. “But these [cosmic rays] are journeying there, and the gamma rays they send back are messengers of the terrible conditions there.”

    More observations are coming soon. NASA’s Parker Solar Probe, which launched on August 12, will take the first direct measurements of the magnetic field in the sun’s outer atmosphere, or corona (SN: 7/21/18, p. 12).

    154f8-sol_parkersolarprobe2_nasa


    NASA Parker Solar Probe Plus

    And as the sun enters the next solar minimum, the highest-energy gamma rays are starting to return. In February, Fermi caught its first gamma ray with an energy above 100 GeV since 2009.

    “There really is something strange afoot,” says solar physicist Craig DeForest of the Southwest Research Institute, who is based in Boulder, Colo., and was not involved in the work. “When there’s some new discovery, scientists don’t shout ‘Eureka!’ They go, ‘Hm, that’s funny. That can’t be right.’ This is a classic case of that.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 12:09 pm on January 12, 2018 Permalink | Reply
    Tags: , CERN MoEDAL collaboration, , , SciNews   

    From SciNews: “Magnets with a single pole are still giving physicists the slip” 

    ScienceNews

    January 9, 2018
    Emily Conover

    Experiments are teasing out new details about the unique properties of ‘magnetic monopoles’.

    1
    SOLE POLE Scientists are searching for hypothetical particles called magnetic monopoles, which have a single north or south magnetic pole. Such particles might be created in pairs (red in the lower right corner and blue in the upper left corner, illustrated above) in collisions of proton beams (white) at accelerators like the Large Hadron Collider. MoEDAL Collaboration

    Magnetic poles are seemingly inseparable: Slice a magnet in half, and you get two smaller magnets, each with its own north and south poles. But exotic magnetic particles that flout this rule may be lurking undetected, some physicists suspect.

    The hunt is in full swing for these hypothetical particles known as magnetic monopoles — which possess a lone north or south pole. Now, two groups of researchers have further winnowed down the particles’ possible masses and characteristics, using data from particle accelerators and the corpses of stars.

    There’s good reason to suspect magnetic monopoles are out there, some physicists suggest. The particles’ existence would explain why electric charge is quantized — why it always seems to come in integer multiples of the charge of an electron instead of a continuous range of values. As a result, magnetic monopoles are popular. “A lot of people think they should exist,” says James Pinfold, a particle physicist at the University of Alberta in Edmonton, Canada.

    If even a single magnetic monopole were detected, the discovery would rejigger the foundations of physics. The equations governing electricity and magnetism are mirror images of one another, but there’s one major difference between the two phenomena. Protons and electrons carry positive and negative electric charges, respectively, but no known particle has a magnetic charge. A magnetic monopole would be the first, and if one were discovered, electricity and magnetism would finally be on equal footing.

    For decades, scientists have searched fruitlessly for magnetic monopoles. Recent work at the Large Hadron Collider, located at the particle physics lab CERN in Geneva, has reinvigorated the search. Magnetic monopoles might be produced there as protons slam together at record-high energies of 13 trillion electron volts.

    Unfortunately, the latest search by Pinfold and collaborators with the Monopole and Exotics Detector at the LHC, or MoEDAL (pronounced “medal”), found no magnetic monopoles, despite analyzing six times the data as the project’s previous pursuits.

    4
    CERN The MoEDAL Nuclear Track Detector System

    Still, the new research has set some of the most stringent constraints yet on how easily the hypothetical particles may interact with matter, the MoEDAL collaboration reports December 28 at arXiv.org.

    ______________________________________________________________
    Parted poles

    All known magnets have both a north and south pole, as illustrated in the inset image, with lines indicating the direction of the magnetic field. Hypothetical particles called magnetic monopoles, envisioned in the wider illustration, would possess only a north or south pole.

    2
    ______________________________________________________________

    Magnetic monopoles may also dwell where magnetic fields are extraordinarily strong and temperatures are high. Under these conditions, pairs of monopoles might form spontaneously. Such extreme environments can be found around a special kind of dead star known as a magnetar, and in the aftermath of collisions of heavy atomic nuclei in particle accelerators. By studying these two scenarios, physicists Arttu Rajantie and Oliver Gould, both of Imperial College London, put new constraints on monopoles’ masses, the researchers report in the Dec. 15 Physical Review Letters.

    If magnetic monopoles had relatively small masses, the particles would sap the strength of magnetars’ magnetic fields. That fact suggests that the particles must be more massive than about 0.3 billion electron volts — about a third the mass of a proton — the researchers calculate. That estimate depends on another unknown property of monopoles, the strength of their magnetic charge. The particles have a minimum possible magnetic charge. A magnetic charge larger than this baseline value would correspond to a minimum mass greater than 0.3 billion electron volts.

    For a monopole with twice the minimum charge, Rajantie and Gould determined that magnetic monopoles must be more massive than about 10 billion electron volts, going by data from collisions of lead nuclei in the Super Proton Synchrotron, a smaller accelerator at CERN.

    CERN Super Proton Synchrotron

    Studying similar collisions of lead nuclei in the LHC could improve this estimate, due to the LHC’s higher collision energies.

    While other experiments have set higher monopole mass limits than the new estimates, those analyses relied on questionable theoretical assumptions, Rajantie says. “These are currently the strongest bounds on the masses of magnetic monopoles that don’t rely on assumptions” about how the particles are created, he says.

    The results are “very exciting,” says theoretical physicist Kimball Milton of the University of Oklahoma in Norman, who was not involved with the research. Of course, he adds, it’s “not as exciting as if somebody actually found a magnetic monopole.”

    Even if monopoles do exist, the particles might be so heavy that they can’t be produced by accelerators or cosmic processes. The only magnetic monopoles in the universe might be remnants of the Big Bang. A future incarnation of MoEDAL, located on a mountaintop instead of in an accelerator’s cavern, could look for such magnetic monopoles that sprinkle down on Earth from space, Pinfold says.

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

    Published since 1922, the biweekly print publication reaches about 90,000 dedicated subscribers and is available via the Science News app on Android, Apple and Kindle Fire devices. Updated continuously online, the Science News website attracted over 12 million unique online viewers in 2016.

    Science News is published by the Society for Science & the Public, a nonprofit 501(c) (3) organization dedicated to the public engagement in scientific research and education.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 10:06 am on January 3, 2018 Permalink | Reply
    Tags: , , , , , Kayuga Japanese spacecraft, Moon Has Earth’s Oxygen Planetary Researchers Say, SciNews,   

    From SciNews: “Moon Has Earth’s Oxygen, Planetary Researchers Say” 


    ScienceNews

    Jan 2, 2018
    No writer credit

    A team of Japanese planetary researchers led by Osaka University’s Professor Kentaro Terada has discovered that the solar wind and Earth’s magnetic field can transport high-energy ions of biogenic oxygen from the atmosphere of our planet to the lunar surface.

    1
    This image shows how the solar wind transports ions of oxygen from the Earth’s atmosphere to the Moon. Image credit: Osaka University / NASA.

    “The Earth is protected from solar wind and cosmic rays by the planet’s magnetic field,” Professor Terada and colleagues explained.

    “On Earth’s night side, its magnetic field is extended like a comet tail and makes a space like a streamer (we call it a ‘geotail’).”

    “At the center of the geotail, there is an area which exists as a sheet-like structure of hot plasma.”

    In a paper published the journal Nature Astronomy, the researchers report observations from the Japanese spacecraft Kaguya of significant numbers of high-energy oxygen ions, seen only when the Moon was in the Earth’s plasma sheet.

    2
    Kayuga Japanese spacecraft produced by Produced by the Institute of Space and Astronautical Science (ISAS) and the National Space Development Agency (NASDA)

    “We succeeded in observing that oxygen from the ionosphere of Earth was transported to the Moon 236,000 miles (380,000 km) away,” they said.

    “We examined plasma data of Kaguya’s Magnetic field and Plasma experiment/Plasma energy Angle and Composition experiment (MAP-PACE) about 62 miles (100 km) above the Moon’s surface, and discovered that high-energy oxygen ions appeared only when the Moon and the spacecraft crossed the plasma sheet.”

    Oxygen ions detected by the team had a high energy of 1-10 keV.

    “These ions can be implanted into a depth of tens of nanometers of a metal particle,” the authors said.

    “This is a very important finding in understanding the complicated isotopic composition of oxygen on the lunar regolith, which has long been a mystery.”

    “Through observations, we demonstrated the possibility that components that lack 16O, which is a stable isotope of oxygen and is observed in the ozone layer, a region of Earth’s stratosphere, were transported to the Moon surface and implanted into a depth of tens of nanometers on the surface of lunar soils.”

    “Our Kaguya observation of significant Earth wind from the current geomagnetic field strengthens the hypothesis that information on the lost ancient atmosphere of our planet could be preserved on the surface of lunar soils,” the scientists concluded.

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

    Published since 1922, the biweekly print publication reaches about 90,000 dedicated subscribers and is available via the Science News app on Android, Apple and Kindle Fire devices. Updated continuously online, the Science News website attracted over 12 million unique online viewers in 2016.

    Science News is published by the Society for Science & the Public, a nonprofit 501(c) (3) organization dedicated to the public engagement in scientific research and education.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 9:17 am on January 3, 2018 Permalink | Reply
    Tags: , SciNews, ,   

    From ScienceNews: “A sinking, melting ancient tectonic plate may fuel Yellowstone’s supervolcano” 

    ScienceNews bloc

    ScienceNews

    January 2, 2018
    Carolyn Gramling

    Computer simulations suggest that a core-deep plume of magma isn’t needed to power the massive eruptions.

    1
    HOT SPOT The Yellowstone supervolcano has a 17-million-year history of eruptions in the western United States. Now scientists say the source of the supervolcano’s heat isn’t a deep mantle plume, but the downward drag of an ancient subducting slab stirring up the mantle. Riishede/iStockphoto.

    Computer simulations show that movement of broken-up remnants of the ancient Farallon Plate could be stirring the mantle in a way that fuels Yellowstone, researchers report December 18 in Nature Geoscience. “The fit is so good,” says study coauthor Lijun Liu, a geodynamicist at the University of Illinois at Urbana-Champaign.

    The giant supervolcano now beneath Yellowstone National Park, located mostly in Wyoming, has a 17-million-year history — much of it on the move. In that time, the locus of volcanism has moved northeastward from southwestern Idaho to its current location, where it most recently explosively erupted about 640,000 years ago. These shifting eruptions have created a track of volcanic craters resembling those created by the hot spot that formed the Hawaiian island chain. As a result, scientists have long suspected that a deep plume of magma originating from the core-mantle boundary, similar to the one that fuels Hawaii’s volcanoes, is the source of Yellowstone’s fury.

    But the nature of the Yellowstone plume has been the subject of debate. “Usually with plumes, we can trace them to the core-mantle boundary,” says Robert Porritt, a seismologist at the University of Texas at Austin, who was not involved in the new work. To “see” Earth’s structure, seismologists use a technique called seismic tomography, which maps the interior using seismic waves generated by earthquakes. Particularly hot or liquid parts of the mantle slow some seismic waves known as shear waves. Tomographic images of mantle plumes such as the one beneath Hawaii show a low-velocity region that extends all the way down to the boundary between mantle and core, about 2,900 kilometers below Earth’s surface. Such deep plumes are thought to be necessary to provide sufficient heat for the volcanism.

    “But at Yellowstone, we don’t have that large low-shear velocity thing at the core-mantle boundary,” Porritt says. Current images suggest a region of low-velocity material extending at least 1,000 kilometers deep — but whether there is a deeper plume is uncertain.

    And the region is tectonically complex. About 200 million years ago, a tectonic plate to the west, known as the Farallon Plate, began to slide eastward beneath the North American Plate. The current Juan de Fuca Plate off the Pacific Northwest coast, one of the last remnants of the Farallon Plate, continues to slide beneath the western United States. Some researchers have suggested that, instead of a deep mantle plume, the flexing and melting of the subducting Juan de Fuca Plate are responsible for Yellowstone’s volcanism.

    ______________________________________________________________________
    Dragging down

    The Farallon Plate began subducting eastward beneath the North American Plate hundreds of millions of years ago. The youngest part of the slab, called the Juan de Fuca Plate (green), now partly lies beneath the western United States. In a new study, simulations suggest that the downward pull of the ancient Farallon Plate (blue) is driving the flow of hot mantle from west to east. As that hot mantle (dark orange) rises through breaks in the Juan de Fuca Plate, some of mantle circulates westward, fueling volcanism in the Basin and Range region. And some flows to the east, fueling Yellowstone.

    2
    Q. Zhou, L. Liu and J. Hu/Nature Geoscience 2017
    ______________________________________________________________________

    Liu and his colleagues have yet another idea. In 2016, Liu published research suggesting that the sinking ancient Farallon slab was acting like a lid on a deep mantle plume, preventing the plume from rising to the surface (SN Online: 2/3/16). “But we kept in mind that the problem was not solved,” Liu says. “The heat source [for Yellowstone] was still missing.”

    The researchers created a sophisticated, supercomputer-driven series of simulations to try to find the best scenario that matches the three known knowns: the current tomographic images of the subsurface beneath the western United States; the volcanic history at Yellowstone as well as in the nearby Basin and Range regions; and the movements of the subducting slab since about 20 million years ago.

    Yellowstone’s volcanism is linked not just to the currently subducting young Juan de Fuca Plate, but also to the remnants of its older incarnation, the Farallon Plate, the simulations suggest. Those remnants have continued to slide deeper and now lie beneath the eastern United States. This downward dive dragged hot mantle eastward along with it. As the Juan de Fuca Plate began to break up beneath the western United States, the hot mantle rose through the cracks. Some of that hot mantle circulated back to the west across the top of the Juan de Fuca Plate, fueling volcanism in the Basin and Range region. And some of it flowed eastward, adding heat to Yellowstone’s fire. The study doesn’t rule out the presence of a deep magma plume, but it suggests that such a plume plays little role in Yellowstone’s volcanism.

    Porritt says he’s intrigued by the idea that the sinking Farallon slab beneath the central and eastern United States could be driving mantle circulation on such a large scale. However, he says, he isn’t convinced that the authors have truly solved the larger mystery of Yellowstone’s volcanism — or that a yet-to-be-found deep plume still isn’t playing a major role. “It’s an interesting debate that’s going to be raging, hopefully for decades.”

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

    Published since 1922, the biweekly print publication reaches about 90,000 dedicated subscribers and is available via the Science News app on Android, Apple and Kindle Fire devices. Updated continuously online, the Science News website attracted over 12 million unique online viewers in 2016.

    Science News is published by the Society for Science & the Public, a nonprofit 501(c) (3) organization dedicated to the public engagement in scientific research and education.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 7:13 am on November 2, 2017 Permalink | Reply
    Tags: , , , , Earth may not provide the best blueprint for how rocky planets are born, Hot rocky exoplanets are the scorched cores of former gas giants, Mini-Neptunes are between 2.5 and four times Earth’s size, Most hot rocky exoplanets started out more like gassy Neptunes, SciNews   

    From SciNews: “Hot, rocky exoplanets are the scorched cores of former gas giants” 


    SciNews

    October 31, 2017
    Lisa Grossman

    The planets are nestled close to their stars, where stellar winds may have blown ancient atmospheres away.

    1
    NOT LIKE HOME Rocky super-Earth 55 Cancri e, seen in this artist’s illustration, is about Earth’s size, but a new study suggests it and other similar hot exoplanets probably formed in a completely different way than Earth did. NASA/ESA Hubble and M. Kornmesser

    Earth may not provide the best blueprint for how rocky planets are born.

    An analysis of planets outside the solar system suggests that most hot, rocky exoplanets started out more like gassy Neptunes. Such planets are rocky now because their stars blew their thick atmospheres away, leaving nothing but an inhospitable core, researchers report in a paper posted online October 15 at arXiv.org [MNRAS]. That could mean these planets are not as representative of Earth as scientists thought, and using them to estimate the frequency of potentially life-hosting worlds is misleading.

    “One of the big discoveries is that Earth-sized, likely rocky planets are incredibly common, at least on hotter orbits,” says planetary scientist Eric Lopez of NASA’s Goddard Space Flight Center in Greenbelt, Md., who wasn’t involved in the study. “The big question is, are those hot exoplanets telling us anything about the frequency of Earthlike planets? This suggests that they might not be.”

    Observations so far suggest that worlds about Earth’s size probably cluster into two categories: rocky super-Earths and gaseous mini-Neptunes (SN Online: 6/19/17). Super-Earths are between one and 1.5 times as wide as Earth; mini-Neptunes are between 2.5 and four times Earth’s size. Earlier work showed that there’s a clear gap between these planet sizes.

    Because planets that are close to their stars are easier for telescopes to see, most of the rocky super-Earths discovered so far have close-in orbits — with years lasting between about two to 100 Earth days — making the worlds way too hot to host life as we know it. But because they are rocky like Earth, scientists include these worlds with their cooler brethren when estimating how many habitable planets might be out there.

    If hot super-Earths start out rocky, perhaps it is because the worlds form later than their puffy mini-Neptune companions, when there’s less gas left in the growing planetary system to build an atmosphere. Or, conversely, such planets, along with mini-Neptunes, may start with thick atmospheres. These rocky worlds may have had their atmospheres stripped away by stellar winds.

    2
    V. Van Eylen et al/arXiv.org 2017

    Now, exoplanet astronomer Vincent Van Eylen of Leiden University in the Netherlands and his colleagues have shown that the fault is in the stars. “You really have these two populations, and the influence of the star is what creates this separation,” Van Eylen says. That result could warn astronomers not to rely too heavily on these hot, rocky worlds when calculating how many habitable planets are likely to exist.

    To measure the planets’ sizes, astronomers need to know the sizes of their stars. Van Eylen and colleagues analyzed 117 planets whose host stars’ sizes had been measured using astroseismology. This technique tracks how often the star’s brightness changes as interior oscillations ripple through it, and uses the frequency to determine its size.

    “Think of the stars as musical instruments,” Van Eylen says. A double bass and a violin produce sound the same way, but the pitch is different because of the instrument’s size. “It’s exactly the same thing with stars.”

    The researchers then calculated the planets’ sizes — between one and four times the Earth — with about four times greater precision than in previous studies. As expected, the planets clustered in groups of around 1.5 and 2.5 times Earth’s radius, leaving a gap in the middle.

    Next the team looked at how the planets’ sizes changed with distance from the host star. Planets that were rocky from the start should be smaller close to the stars, where studies of other young star systems suggest there should have been less material available when these planets were forming. But if proximity to a star’s winds is key, there should be some larger rocky worlds closer in, with smaller gaseous worlds farther out.

    Van Eylen’s planets matched the second picture: The largest of the rocky planets nestled close to the stars were bigger than the distant ones. That suggests the rocky planets once had atmospheres, and lost them.

    “It’s not fair to take the close-in planets and assume that the more distant planets are just like them,” says exoplanet astronomer Courtney Dressing of the University of California, Berkeley. “You might be fooling yourself.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 6:50 am on November 2, 2017 Permalink | Reply
    Tags: , , , , Laboratory experiments that mimic maturing stars show that streams of plasma splash off a star’s surface forming a varnish that keeps certain kinds of radiation inside, SciNews, The way hungry young stars suck in food keeps most X-rays in too   

    From SciNews: “The way hungry young stars suck in food keeps most X-rays in, too” 


    SciNews

    November 1, 2017
    Lisa Grossman

    Lab re-creation of feeding process will help better calculate how fast stars grow.

    1
    HOW DOES YOUR STAR GROW? Young stars are surrounded by disks of dust and gas that will eventually form planets, as shown in this artist’s illustration. But first, the stars suck material out of the disk via columns shaped by magnetic fields. L. Calçada/ESO


    A THIN VENEER This simulation of a laboratory setup that mimics a feeding star shows how a column of plasma (center, yellow and blue) splashes off a surface representing a star. The plasma spreads upwards and coats the original column. The left side of the simulation represents the plasma density, and the right side represents temperature. G. Revet et al/Science Advances 2017

    A plasma cocoon lets growing stars keep their X-rays to themselves. Laboratory experiments that mimic maturing stars show that streams of plasma splash off a star’s surface, forming a varnish that keeps certain kinds of radiation inside.

    That coating could explain a puzzling mismatch between X-ray and ultraviolet observations of growing stars, report physicist Julien Fuchs of École Polytechnique in Paris and colleagues November 1 in Science Advances.

    Physicists think stars that are less than 10 million years old grow up by drawing matter onto their surfaces from an orbiting disk of dust and gas. Magnetic fields shape the incoming matter into columns of hot, charged plasma. The same disk will eventually form planets (SN Online: 11/6/14), so knowing how quickly stars gobble up the disk can help tell what kinds of planets can grow.

    When disk matter hits a stellar surface, the matter heats to about 1,700° Celsius and should emit a lot of light in ultraviolet and X-ray wavelengths. Measuring that light can help scientists infer how fast the star is growing. But previous observations found that such stars emit between four and 100 times fewer X-rays than they should.

    One theory why is that something about how a star eats absorbs the X-rays. So Fuchs and his colleagues re-created the feeding process in a lab. First, the team zapped a piece of PVC representing the edge of the disk with a laser to create plasma, similar to the columns that feed stars. In space, a star’s gravity draws the plasma onto its surface at speeds of about 500 kilometers per second. The star’s strong magnetic field guides the charged plasma into organized columns millions of kilometers long.

    There’s not enough room or gravity in the lab to reproduce that exactly, but the plasma physics is the same on smaller scales, Fuchs says. His team applied magnetic fields up to 100,000 times stronger than Earth’s to the plasma to shape it into columns and accelerate it to the same speed it would have in space. The researchers placed a target made of Teflon representing the star’s surface just 11.7 millimeters away from the PVC, a distance equivalent to about 10 million kilometers in space.

    When the plasma hits the Teflon surface, the plasma begins to ooze sideways. But the magnetic field that holds the plasma in a column stops the plasma’s spreading. Plasma and magnetic field push against each other until the buildup of pressure between them forces the plasma to curve away from the surface and back up the column, coating incoming plasma with outgoing plasma.

    “This cocoon is building up,” Fuchs says. It absorbs enough X-rays to explain the surprisingly wimpy X-ray emission of growing stars, the experiment found. The team also compared the experiment setup with computer simulations of feeding stars to show that the lab configuration was a good representation of real stars.

    The comparison with computer simulations makes the experiment more reliable, says experimental physicist Gianluca Gregori of the University of Oxford. “There is this reality check,” he says. “In the astrophysical community, there’s a tendency to think that there are observations, and there are simulations. But what this paper tells is that there are other ways you can understand what happens in the universe.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 7:23 am on October 31, 2017 Permalink | Reply
    Tags: , Photons are caught behaving like superconducting electrons, , SciNews   

    From SciNews: “Photons are caught behaving like superconducting electrons” 

    src=”https://sciencesprings.files.wordpress.com/2016/08/scinews-bloc.jpg” alt=”SciNews bloc” width=”552″ height=”88″ class=”alignnone size-full wp-image-47642″ />

    SciNews

    October 30, 2017
    Emily Conover

    Whether the particles of light can produce a supercurrent remains to be seen.

    1
    PHOTON PAIRS Laser light in water (shown) exhibits an unexpected quirk: Light particles interact with their companions in the same way electrons pair up in superconductors. GIPhotoStock/Science Source

    Light is a fan of the buddy system. Photons, or particles of light, have been spotted swapping energy with partners. This chummy behavior resembles how electrons pair up in materials that conduct current without resistance, known as superconductors, researchers report in a paper accepted in Physical Review Letters.

    Although the photons exchange energy like electrons do, it’s unknown whether the particles are actually bound together as electrons are, and whether photons could produce an effect analogous to superconductivity. “This is a door that is opened,” says study coauthor Ado Jorio, a physicist at the Universidade Federal de Minas Gerais in Brazil. Now, he says, the questions that must be addressed are, “How far can we push this similarity? Can we find with photons incredible results like we find for electrons?”

    In certain solid materials cooled to extremely low temperatures, electrons form partnerships called Cooper pairs (SN: 6/13/15, p. 8), which allow superconductivity to occur. Although the negatively charged particles typically repel one another, two electrons can bind together by exchanging phonons, or quantum packets of vibration, via the lattice of ions within these materials. This alliance coordinates the electrons’ movements and thereby eases their passage through the material, allowing them to flow without resistance. Superconductivity’s potential technological applications — which include energy-efficient power transmission, superstrong magnets and levitating trains — have attracted heaps of scientific interest in the phenomenon.

    Now, Jorio and colleagues have shown photons behaving similarly to superconducting electrons. When the researchers shined a laser on water, pairs of photons that emerged from the liquid at the same time tended to have complementary energies. While one photon had lost a little energy, another had gained the same amount of energy, indicating that they were exchanging quantum vibrations. The effect appeared in a variety of transparent materials, says Jorio, and it was observed at room temperature, unlike electron pairing in superconductors.

    The team also showed that the exchanged quantum vibrations were “virtual” — appearing only for fleeting moments — just like the vibrations exchanged by electrons. The theory that explains the interaction “is exactly the same as for the electrons,” Jorio says.

    Scientists already knew that photons can lose or gain energy via vibrations, but the similarity with Cooper pairs is a new and interesting way of thinking about the effect, says physicist Ian Walmsley of Oxford University, who was not involved with the research. “It’s a field that has not yet been explored.”

    It is still too early to know how far the analogy with superconducting electrons extends, says physicist Ben Sussman of the National Research Council of Canada in Ottawa, who was not involved with the research. But the connection seems worth investigating: “This is an interesting rabbit hole indeed.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 9:01 am on August 29, 2016 Permalink | Reply
    Tags: , , , , SciNews   

    From SciNews: “Hubble Space Telescope Snaps Image of Alpha Centauri AB” 

    SciNews bloc

    SciNews

    Aug 29, 2016
    Enrico de Lazaro

    The Hubble Space Telescope team has released an incredible new image of the binary star Alpha Centauri AB.

    1
    This Hubble WFPC2 image shows Alpha Centauri A (left) and Alpha Centauri B (right). Image credit: NASA / ESA / Hubble.

    Alpha Centauri, the closest stellar system to Earth, is located in the constellation of Centaurus.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker
    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Also known as Rigil Kentaurus, Rigil Kent and Gliese 559, this triple system is made up of the bright binary star formed by Alpha Centauri A and Alpha Centauri B, plus the faint red dwarf star Alpha Centauri C.

    The two brighter components are roughly 4.35 light years away from us. Alpha Centauri C, better known as Proxima Centauri, is slightly closer at 4.23 light years.

    Compared to the Sun, Alpha Centauri A is of the same stellar type G2, and slightly bigger (1.1 times more massive than the Sun and about 1.5 times more luminous).

    Alpha Centauri B, a K1-type star, is slightly smaller and less bright (0.9 times the mass of the Sun and about 45% of its visual luminosity).

    Alpha Centauri A and B orbit a common center of gravity once every 80 years, with a minimum distance of about 11 times the distance between the Earth and the Sun.

    Because these two stars are, together with Proxima Centauri, our nearest interstellar neighbors, they are among the best studied by astronomers.

    And they are also among the prime targets in the hunt for potentially habitable planets.

    Using the HARPS instrument on the 3.6-m telescope at ESO’s La Silla Observatory, Chile, astronomers already discovered a planet orbiting Alpha Centauri B. The planet, designated Alpha Centauri Bb, has a mass of a little more than that of the Earth and orbits its host star once every 3.2 days.

    Earlier this month, astronomers announced the discovery of an Earth-mass planet in the habitable zone orbiting Proxima Centauri. Named Proxima b, the planet orbits its star every 11 days and has a temperature suitable for liquid water to exist on its surface.

    This image of Alpha Centauri AB is a composite of separate exposures acquired by Hubble’s Wide Field and Planetary Camera 2 (WFPC2).

    It is based on data obtained through two filters: F457W and F850W.

    The color results from assigning different hues to each monochromatic image associated with an individual filter.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: