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  • richardmitnick 11:57 am on September 5, 2017 Permalink | Reply
    Tags: "Minuscule jitters may hint at quantum collapse mechanism, , , , Science News,   

    From Science News: “Minuscule jitters may hint at quantum collapse mechanism” 

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    ScienceNews

    September 1, 2017
    Emily Conover

    Data match prediction for wave function theory, but more experiments are needed.

    1
    A tiny, shimmying cantilever wiggles a bit more than expected in a new experiment. The excess jiggling of the miniature, diving board–like structure might hint at why the strange rules of quantum mechanics don’t apply in the familiar, “classical” world. But that potential hint is still a long shot: Other sources of vibration are yet to be fully ruled out, so more experiments are needed.

    Quantum particles can occupy more than one place at the same time, a condition known as a superposition (SN: 11/20/10, p. 15). Only once a particle’s position is measured does its location become definite. In quantum terminology, the particle’s wave function, which characterizes the spreading of the particle, collapses to a single location (SN Online: 5/26/14).

    In contrast, larger objects are always found in one place. “We never see a table or chair in a quantum superposition,” says theoretical physicist Angelo Bassi of the University of Trieste in Italy, a coauthor of the study, to appear in Physical Review Letters. But standard quantum mechanics doesn’t fully explain why large objects don’t exist in superpositions, or how and why wave functions collapse.

    Extensions to standard quantum theory can alleviate these conundrums by assuming that wave functions collapse spontaneously, at random intervals. For larger objects, that collapse happens more quickly, meaning that on human scales objects don’t show up in two places at once.

    Now, scientists have tested one such theory by looking for one of its predictions: a minuscule jitter, or “noise,” imparted by the random nature of wave function collapse. The scientists looked for this jitter in a miniature cantilever, half a millimeter long. After cooling the cantilever and isolating it to reduce external sources of vibration, the researchers found that an unexplained trembling still remained.

    In 2007, physicist Stephen Adler of the Institute for Advanced Study in Princeton, N.J., predicted that the level of jitter from wave function collapse would be large enough to spot in experiments like this one. The new measurement is consistent with Adler’s prediction. “That’s the interesting fact, that the noise matches these predictions,” says study coauthor Andrea Vinante, formerly of the Institute for Photonics and Nanotechnologies in Trento, Italy. But, he says, he wouldn’t bet on the source being wave function collapse. “It is much more likely that it’s some not very well understood effect in the experiment.” In future experiments, the scientists plan to change the design of the cantilever to attempt to isolate the vibration’s source.

    The result follows similar tests performed with the LISA Pathfinder spacecraft, which was built as a test-bed for gravitational wave detection techniques. Two different studies found no excess jiggling Physical Review D] of free-falling weights [Physical Review D] within the spacecraft. But the new cantilever experiment tests for wave function collapse occurring at different rate and length scales than those previous studies.

    ESA/LISA Pathfinder

    Two different studies found no excess jiggling of free-falling weights within the spacecraft. But the new cantilever experiment tests for wave function collapse occurring at different rate and length scales than those previous studies.

    Theories that include spontaneous wave function collapse are not yet accepted by most physicists. But interest in them has recently become more widespread, says physicist David Vitali of the University of Camerino in Italy, “sparked by the fact that technological advances now make fundamental tests of quantum mechanics much easier to conceive.” Focusing on a simple system like the cantilever is the right approach, says Vitali, who was not involved with the research. Still, “a lot of things can go wrong or can be not fully controlled.”

    To conclude that wave function collapse is the cause of the excess vibrations, every other possible source will have to be ruled out. So, Adler says, “it’s going to take a lot of confirmation to check that this is a real effect.”

    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.

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  • richardmitnick 11:21 am on August 31, 2017 Permalink | Reply
    Tags: , , , Science News, Star that exploded in 1437 tracked to its current position   

    From Science News: “Star that exploded in 1437 tracked to its current position” 

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    ScienceNews

    August 30, 2017
    Lisa Grossman

    1
    CANNIBAL ZOMBIE STAR Dead stars called white dwarfs (left) steal material from ordinary companion stars (right), as shown in this artist’s illustration. When the white dwarf has devoured enough material, it can explode as a nova. JPL-Caltech/NASA

    Some stars erupt like clockwork. Astronomers have tracked down a star that Korean astronomers saw explode nearly 600 years ago and confirmed that it has had more outbursts since.


    Carnegie Institution Swope telescope at Las Campanas, Chile

    3
    The 1437 nova and its ejected shell, spotted in 2016. (K. Ilkiewicz, J. Mikolajewska and M.M. Shara/Nature 2017)
    That star today (marked “2016” and set off with red lines) is far from the cloud’s center, but researchers used historical data to trace it back to its 1437 position.
    The diffuse cloud in this image, taken with the Carnegie Institution for Science’s Swope telescope in Chile, is the shell of hot hydrogen gas ejected by a white dwarf star on March 11, 1437.

    The finding suggests that what were thought to be three different stellar objects actually came from the same object at different times, offering new clues to the life cycles of stars.

    On March 11, 1437, Korean royal astronomers saw a new “guest star” in the tail of the constellation Scorpius. The star glowed for 14 days, then faded. The event was what’s known as a classical nova explosion, which occurs when a dense stellar corpse called a white dwarf steals enough material from an ordinary companion star for its gas to spontaneously ignite. The resulting explosion can be up to a million times as bright as the sun, but unlike supernovas, classical novas don’t destroy the star.

    Astronomer Michael Shara of the American Museum of Natural History in New York City and colleagues used digitized photographic plates dating from as early as 1923 to trace a modern star back to the nova. The team tracked a single star as it moved away from the center of a shell of hot gas, the remnants of an old explosion, thus showing that the star was responsible for the nova. The researchers also saw the star, which they named Nova Scorpii AD 1437, give smaller outbursts called dwarf novas in the 1930s and 1940s. The findings were reported in the Aug. 31 Nature.

    The discovery fits with a proposal Shara and colleagues made in the 1980s. They suggested that three different stellar observations — bright classical nova explosions, dwarf nova outbursts and an intermediate stage where a white dwarf is not stealing enough material to erupt — are all different views of the same system.

    “In biology, we might say that an egg, a larva, a pupa and a butterfly are all the same system seen at different stages of development,” Shara 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.

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  • richardmitnick 6:42 am on August 29, 2017 Permalink | Reply
    Tags: , , , , , , , Rumors swirl that LIGO snagged gravitational waves from a neutron star collision, Science News   

    From Science News: “Rumors swirl that LIGO snagged gravitational waves from a neutron star collision” 

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    ScienceNews

    August 25, 2017
    Emily Conover

    1
    CRASH AND FLASH Rumors suggest that LIGO may have detected gravitational waves from a new source: colliding neutron stars (illustrated). Such cataclysms are expected to generate a high-energy flash of light, called a gamma-ray burst (yellow jets). Several telescopes made observations seemingly in search of light from such events.

    Speculation is running rampant about potential new discoveries of gravitational waves, just as the latest search wound down August 25.

    Publicly available logs from astronomical observatories indicate that several telescopes have been zeroing in on one particular region of the sky, potentially in response to a detection of ripples in spacetime by the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    These records have raised hopes that, for the first time, scientists may have glimpsed electromagnetic radiation — light — produced in tandem with gravitational waves. That light would allow scientists to glean more information about the waves’ source. Several tweets from astronomers reporting rumors of a new LIGO detection have fanned the flames of anticipation and amplified hopes that the source may be a cosmic convulsion unlike any LIGO has seen before.

    “There is a lot of excitement,” says astrophysicist Rosalba Perna of Stony Brook University in New York, who is not involved with the LIGO collaboration. “We are all very anxious to actually see the announcement.”

    An Aug. 25 post on the LIGO collaboration’s website announced the end of the current round of data taking, which began November 30, 2016. Virgo, a gravitational wave detector in Italy, had joined forces with LIGO’s two on August 1 (SN Online: 8/1/17).


    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    The three detectors will now undergo upgrades to improve their sensitivity. The update noted that “some promising gravitational-wave candidates have been identified in data from both LIGO and Virgo during our preliminary analysis, and we have shared what we currently know with astronomical observing partners.”

    When LIGO detects gravitational waves, the collaboration alerts astronomers to the approximate location the waves seemed to originate from. The hope is that a telescope could pick up light from the aftermath of the cosmic catastrophe that created the gravitational waves — although no light has been found in previous detections.


    SPIRAL IN Two neutron stars orbit one another and spiral inward until they merge in this animation. The collision emits gravitational waves and a burst of light.

    Since mid-August, seemingly in response to a LIGO alert, several telescopes have observed a section of sky around the galaxy NGC 4993, located 134 million light-years away in the constellation Hydra. The Hubble Space Telescope has made at least three sets of observations in that vicinity, including one on August 22 seeking “observations of the first electromagnetic counterparts to gravitational wave sources.”

    NASA/ESA Hubble Telescope

    Likewise, the Chandra X-ray Observatory targeted the same region of sky on August 19.

    NASA/Chandra Telescope

    And records from the Gemini Observatory’s telescope in Chile indicate several potentially related observations, including one referencing “an exceptional LIGO/Virgo event.”


    Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    “I think it’s very, very likely that LIGO has seen something,” says astrophysicist David Radice of Princeton University, who is not affiliated with LIGO. But, he says, he doesn’t know whether its source has been confirmed as merging neutron stars.

    LIGO scientists haven’t commented directly on the veracity of the rumor. “We have some substantial work to do before we will be able to share with confidence any quantitative results. We are working as fast as we can,” LIGO spokesperson David Shoemaker of MIT wrote in an e-mail.

    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.

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  • richardmitnick 8:53 am on August 22, 2017 Permalink | Reply
    Tags: , , , , Eclipse, NCAR-National Center for Atmospheric Research, Science News, , The spectrometer will measure the corona in infrared wavelengths between 1 and 6 micrometers   

    From Science News: “On a mountain in Wyoming, the eclipse brings wonder — and, hopefully, answers” 

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    ScienceNews

    August 21, 2017
    Lisa Grossman

    1
    TOTALLY AMAZING Keon Gibson, an intern for the National Center for Atmospheric Research, shot the moment of totality through a telescope atop Casper Mountain, Wyo., on August 21. The corona stretches around the moon-blocked sun. The planet Mercury is visible in the bottom left.

    CASPER MOUNTAIN, Wyo. — It’s nothing like a sunset. It’s cold and dark, but it’s not like nighttime, or even twilight. The moon just snaps into place over the last slivers of the sun, turning the sun into a dark hole. The only illumination — a flat, ghostly, metallic sort of light — is from peaked gossamer streamers stretching out toward the edges of the sky.

    I’ve been writing about eclipse science and interviewing researchers who study that eerie halo for the better part of a month. I thought I knew what to expect from my first total solar eclipse.

    I had no idea.

    I’m at a Baptist summer camp called Camp Wyoba about a half hour’s drive up a mountain from Casper, Wyo., with a group of engineers and solar physicists. Most come from the National Center for Atmospheric Research, or NCAR, in Boulder, Colo.

    Our presence here is a stroke of luck: Retired NCAR researcher William Mankin’s wife Mary Beth is a Baptist pastor. When they realized the camp would be in the path of the total eclipse, the Mankins suggested holding an event, complete with a scientific lecture the night before and a church service in the morning. They also invited Mankin’s former NCAR colleagues to bring their experiments — and their families.

    The day before the eclipse, scientists tested their equipment in a field at the top of Casper Mountain near camp, while a group of kids played dodgeball nearby. But by afternoon, the team’s luck seemed to be flagging. One of their telescopes started malfunctioning in a way they hadn’t seen before. They had less than 24 hours to fix it. “It’s a very bad thing if we can’t get it going,” said instrument leader Steven Tomczyk.

    Tomczyk and his colleagues schlepped three telescopes and a spectrometer the size of a coffee table up here to try to solve one of the greatest mysteries of the sun’s corona: Why this ethereal solar atmosphere is so much hotter than the sun’s surface?


    INTO THE DARK This time-lapse video shows how a group of solar physicists and engineers studying the sun’s wispy atmosphere kept busy during totality, but also got to take a look at the corona with their own eyes. In the foreground, Paul Bryans and Ben Berkey uncover and cover the telescopes’ lenses, while Steven Tomczyk, Alyssa Boll and Keon Gibson record data and Philip Judge calls out the time. Lisa Grossman.

    The visible surface of the sun is about 5,500° Celsius. Higher up in the sun’s atmosphere, though, the temperature jumps to 10,000° C and then makes a sudden leap to millions of degrees. It’s a real puzzle why. Most materials transfer heat via atoms smacking into each other or through swirling, churning currents. In the corona, which is made of a diffuse charged gas called plasma, particles are so far apart that neither scenario seems likely.

    Solar physicists are pretty sure that the corona’s magnetic field is somehow to blame for the heat up (SN Online: 8/16/17), but it’s so weak that it has never been measured directly. So the team in Wyoming hopes to chip away at understanding that magnetic field. Their experiments will take steps toward measuring its strength and shape so that a future telescope can make a more complete measurement.

    The spectrometer will measure the corona in infrared wavelengths between 1 and 6 micrometers — the first time it has been measured fully in this range. Infrared light is a good probe of the magnetic field because stronger magnetic fields change the way light is emitted in that range. Atoms in the corona are so hot that they give up many of their electrons — iron atoms have been known to lose up to half of their original count. The remaining electrons are often excited to higher energy levels, and when they drop back into their original state, they emit a particle of light in a particular wavelength. That photon shows up as a peak in the spectrum.

    Magnetic fields make the higher energy levels split into two new levels, so electrons dive from two different platforms and emit different particles of light. That makes the peak split in two as well. The stronger the magnetic field, the farther the distance between the peaks.

    The spectrometer won’t directly view the sun — it’s inside a trailer. A hole in the trailer wall leads to an angled mirror, which will track the eclipsed sun as it moves across the sky and direct the light into the instrument.

    There, a beam splitter will split the light in two and direct it through a series of gold-plated mirrors. Ultimately, the light beams will be recombined. If all goes well, the shape of the light wave at the end will allow the team to calculate the sun’s infrared spectrum. They’re looking for already known peaks in the spectrum — one from silicon that has lost eight electrons, for instance, was observed in 2003 when the sun wasn’t eclipsed — and ones theorized in the 1990s but never observed.

    “We’re at the ragged edge of our signal to noise,” says James Hannigan, who’s in charge of the spectrometer. “I’m really not sure what we’re gonna see.”

    This eclipse is this instrument’s maiden voyage; it was designed in the 1990s but completed only a few months ago. It has had some last-minute headaches, too, Hannigan says. The beam splitter, a sort of half-transparent mirror, had to be polished until its height varied no more than 80 nanometers — or 80 billionths of a meter. It was so difficult to do that the piece of equipment arrived at Hannigan’s house only nine days before the eclipse. “It’s a little more harried than I would have liked,” Hannigan says. “I would have loved to have been testing this thing for the last month and a half, but so it goes.”

    Outside, Tomczyk and the rest of the crew are testing the three telescopes. One will take a picture of the entire corona in infrared wavelengths out to 10 solar radii away from the sun’s surface. That will provide context for the other measurements, letting the team figure out the strength of the field in different parts of the corona.

    Another is actually two telescopes linked together: one infrared and one that measures visible wavelengths. Both send data to a spectrograph, which splits light into all its component wavelengths. The visible light telescope’s job is to take a quick spectrum of the layers of the sun’s atmosphere between the photosphere and the corona, an area called the chromosphere.

    3
    FIRST LOOK The NCAR team’s visible light telescope captured the sun’s spectrum in the last few seconds of totality. This is an example of the data the team will sort through in the coming weeks. Solar physicist Philip Judge says he already sees some tantalizing features in it. P. Judge/NCAR.

    The chromosphere is only visible for a few seconds at the beginning and end of an eclipse. For those few seconds, the visible telescope will take a picture once every 1/125th of a second. “It will help us understand how the atmosphere is changing with height, which helps connect the corona to the surface,” says Philip Judge, one of the experiment’s principal investigators.

    The third telescope — a polarization camera that will measure the magnetic field’s shape — is the one that’s acting up.

    “We’ve been rehearsing this dance over the last couple of days,” says Ben Berkey, who works for NCAR in Hawaii. They’ve practiced every motion they’ll make during the eclipse: Check that the sun is in each telescope’s field of view; remove the lens caps at just the right moment, to get as much time watching the corona as possible without frying the delicate instruments; and so on.

    “If things are boring, that’s not a bad thing necessarily,” Tomczyk says during one run-through.

    “But you won’t be bored,” says Paul Bryans, one of the science leads. “You’ll be watching the partial eclipse.”

    By 4 p.m., the problem with the polarimeter is solved: The computer storing the data needed its hard drive reconfigured. The team is so nervous about losing the data that they plan to make four copies of the hard drives before leaving Casper Mountain, and send them back to NCAR in four different cars, just in case. “They’re precious,” Tomczyk says.

    The morning of the eclipse dawns cool and clear.

    It’s already getting chilly when Judge bellows, “Two-minute warning!” The team jumps into action, taking peeks at the last tiny slices of sunlight through eclipse glasses.

    The moment of totality is sudden and absolute. The corona pops into view all at once, pointing its silvery arms at the treetops and the sky. People cheer; some children scream. Someone lends me a pair of binoculars, and through them I can see the chromosphere, glowing red and purple. I can see Mercury, nestled right up next to the corona.

    And just as suddenly, it’s over. Judge counts down the seconds to the end of totality, and right on schedule, the sun returns. It’s incredible how much light that tiny dot of sunlight provides. I had been told that a 99 percent eclipse is nothing at all like a total eclipse. I get it now.

    Tomczyk and the crew, meanwhile, are already backing up their data and taking the telescopes off their tripods. All the instruments worked, although they’ll have to take the data back to Boulder and process it to know if they got all they’d hoped for.

    “Who knows what we’ll see,” Tomczyk says. “I feel exhausted. And relieved.”

    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.

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  • richardmitnick 12:45 pm on August 15, 2017 Permalink | Reply
    Tags: Eclipse Mob participants, Ionosphere, Science News, Using smartphones and radio kits researchers will track changes in how radio waves travel through the ionosphere, What happens in Earth’s atmosphere during an eclipse?   

    From Science News: “What happens in Earth’s atmosphere during an eclipse?” 

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    ScienceNews

    August 13, 2017
    Lisa Grossman

    Using smartphones and radio kits, researchers will track changes in how radio waves travel through the ionosphere.

    1
    DOWN FROM ABOVE Sunlight strips electrons from atoms in the atmosphere, creating a charged layer called the ionosphere. But that process stops without direct sunlight — like during a solar eclipse.

    As the moon’s shadow races across North America on August 21, hundreds of radio enthusiasts will turn on their receivers — rain or shine. These observers aren’t after the sun. They’re interested in a shell of electrons hundreds of kilometers overhead, which is responsible for heavenly light shows, GPS navigation and the continued existence of all earthly beings.

    This part of the atmosphere, called the ionosphere, absorbs extreme ultraviolet radiation from the sun, protecting life on the ground from its harmful effects. “The ionosphere is the reason life exists on this planet,” says physicist Joshua Semeter of Boston University.

    It’s also the stage for brilliant displays like the aurora borealis, which appears when charged material in interplanetary space skims the atmosphere. And the ionosphere is important for the accuracy of GPS signals and radio communication.

    This layer of the atmosphere forms when radiation from the sun strips electrons from, or ionizes, atoms and molecules in the atmosphere between about 75 and 1,000 kilometers above Earth’s surface. That leaves a zone full of free-floating negatively charged electrons and positively charged ions, which warps and wefts signals passing through it.

    Without direct sunlight, though, the ionosphere stops ionizing. Electrons start to rejoin the atoms and molecules they abandoned, neutralizing the atmosphere’s charge. With fewer free electrons bouncing around, the ionosphere reflects radio waves differently, like a distorted mirror.

    We know roughly how this happens, but not precisely. The eclipse will give researchers a chance to examine the charging and uncharging process in almost real time.

    “The eclipse lets us look at the change from light to dark to light again very quickly,” says Jill Nelson of George Mason University in Fairfax, Va.

    Joseph Huba and Douglas Drob of the U.S. Naval Research Laboratory in Washington, D.C., predicted some of what should happen to the ionosphere in the July 17 Geophysical Research Letters. At higher altitudes, the electrons’ temperature should decrease by 15 percent. Between 150 and 350 kilometers above Earth’s surface, the density of free-floating electrons should drop by a factor of two as they rejoin atoms, the researchers say. This drop in free-floating electrons should create a disturbance that travels along Earth’s magnetic field lines. That echo of the eclipse-induced ripple in the ionosphere may be detectable as far away as the tip of South America.

    Previous experiments during eclipses have shown that the degree of ionization doesn’t simply die down and then ramp back up again, as you might expect. The amount of ionization you see seems to depend on how far you are from being directly in the moon’s shadow.

    For a project called Eclipse Mob, Nelson and her colleagues will use volunteers around the United States to gather data on how the ionosphere responds when the sun is briefly blocked from the largest land area ever.

    2
    DO-IT-YOURSELF Participants in the crowdsourced Eclipse Mob experiment put together their own receivers from parts they received in a kit. This is the completed circuitry, which can plug into the headphone jack of a smartphone to record radio signals sent from transmitters in Colorado and California. K.C. Kerby-Patel.

    About 150 Eclipse Mob participants received a build-it-yourself kit for a small radio receiver that plugs into the headphone jack of a smartphone. Others made their own receivers after the project ran out of kits. On August 21, the volunteers will receive signals from radio transmitters and record the signal’s strength before, during and after the eclipse.

    Nelson isn’t sure what to expect in the data, except that it will look different depending on where the receivers are. “We’ll be looking for patterns,” she says. “I don’t know what we’re going to see.”

    Semeter and his colleagues will be looking for the eclipse’s effect on GPS signals. They would also like to measure the eclipse’s effects on the ionosphere using smartphones — eventually.

    For this year’s solar eclipse, they will observe radio signals using an existing network of GPS receivers in Missouri, and intersperse it with small, cheap GPS receivers that are similar to the kind in most phones. The eclipse will create a big cool spot, setting off waves in the atmosphere that will propagate away from the moon’s shadow. Such waves leave an imprint on the ionosphere that affects GPS signals. The team hopes to combine high-quality data with messier data to lay the groundwork for future experiments to tap into the smartphone crowd.

    “The ultimate vision of this project is to leverage all 2 billion smartphones around the planet,” Semeter says. Someday, everyone with a phone could be a node in a global telescope.

    If it works, it could be a lifesaver. Similar atmospheric waves were seen radiating from the source of the 2011 earthquake off the coast of Japan (SN Online: 6/16/11). “The earthquake did the sort of thing the eclipse is going to do,” Semeter says. Understanding how these waves form and move could potentially help predict earthquakes in the future.

    Further reading
    See the full article with further references with links.

    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

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  • richardmitnick 8:08 am on June 22, 2017 Permalink | Reply
    Tags: , Bones make hormones that communicate with the brain and other organs, , Science News   

    From Science News: “Bones make hormones that communicate with the brain and other organs” 

    ScienceNews bloc

    ScienceNews

    June 21, 2017
    Cassie Martin

    Mouse studies reveal bone-body connection in appetite, metabolism and more.

    1
    BONE UP The skeleton doesn’t just protect important bodily organs, it also talks to them, studies in mice show. Ted Kinsman/Science Source

    Long typecast as the strong silent type, bones are speaking up.

    In addition to providing structural support, the skeleton is a versatile conversationalist. Bones make hormones that chat with other organs and tissues, including the brain, kidneys and pancreas, experiments in mice have shown.

    “The bone, which was considered a dead organ, has really become a gland almost,” says Beate Lanske, a bone and mineral researcher at Harvard School of Dental Medicine. “There’s so much going on between bone and brain and all the other organs, it has become one of the most prominent tissues being studied at the moment.”

    At least four bone hormones moonlight as couriers, recent studies show, and there could be more. Scientists have only just begun to decipher what this messaging means for health. But cataloging and investigating the hormones should offer a more nuanced understanding of how the body regulates sugar, energy and fat, among other things.

    Of the hormones on the list of bones’ messengers — osteocalcin, sclerostin, fibroblast growth factor 23 and lipocalin 2 — the last is the latest to attract attention. Lipocalin 2, which bones unleash to stem bacterial infections, also works in the brain to control appetite, physiologist Stavroula Kousteni of Columbia University Medical Center and colleagues reported in the March 16 Nature.

    2
    R.D. Palmiter/Nature 2017

    Researchers previously thought that fat cells were mostly responsible for making lipocalin 2, or LCN2. But in mice, bones produce up to 10 times as much of the hormone as fat cells do, Kousteni and colleagues showed. And after a meal, mice’s bones pumped out enough LCN2 to boost blood levels three times as high as premeal levels. “It’s a new role for bone as an endocrine organ,” Kousteni says.

    Clifford Rosen, a bone endocrinologist at the Center for Molecular Medicine in Scarborough, Maine, is excited by this new bone-brain connection. “It makes sense physiologically that there are bi­directional interactions” between bone and other tissues, Rosen says. “You have to have things to regulate the fuel sources that are necessary for bone formation.”

    Bones constantly reinvent themselves through energy-intensive remodeling. Cells known as osteoblasts make new bone; other cells, osteoclasts, destroy old bone. With such turnover, “the skeleton must have some fine-tuning mechanism that allows the whole body to be in sync with what’s happening at the skeletal level,” Rosen says. Osteoblasts and osteoclasts send hormones to do their bidding.

    Scientists began homing in on bones’ molecular messengers a decade ago (SN: 8/11/07, p. 83). Geneticist Gerard Karsenty of Columbia University Medical Center found that osteocalcin — made by osteoblasts — helps regulate blood sugar [NIH]. Osteocalcin circulates through the blood, collecting calcium and other minerals that bones need. When the hormone reaches the pancreas, it signals insulin-making cells to ramp up production, mouse experiments showed. Osteocalcin also signals fat cells to release a hormone that increases the body’s sensitivity to insulin, the body’s blood sugar moderator, Karsenty and colleagues reported in Cell in 2007. If it works the same way in people, Karsenty says, osteocalcin could be developed as a potential diabetes or obesity treatment.

    “Their data is fairly convincing,” says Sundeep Khosla, a bone biologist at the Mayo Clinic in Rochester, Minn. “But the data in humans has been less than conclusive.” In observational studies of people, it’s hard to say that osteocalcin directly influences blood sugar metabolism when there are so many factors involved.

    More recent mouse data indicate that osteocalcin may play a role in energy metabolism. After an injection of the hormone, old mice could run as far as younger mice. Old mice that didn’t receive an osteocalcin boost ran about half as far, Karsenty and colleagues reported last year in Cell Metabolism. As the hormone increases endurance, it helps muscles absorb more nutrients. In return, muscles talk back to bones, telling them to churn out more osteocalcin.

    There are hints that this feedback loop works in humans, too. Women’s blood levels of osteocalcin increased during exercise [Cell], the team reported.

    Mounting evidence from the Karsenty lab suggests that osteocalcin also could have more far-flung effects. It stimulates cells in testicles to pump out testosterone — crucial for reproduction and bone density — and may also improve mood and memory, studies in mice have shown. Bones might even use the hormone to talk to a fetus’s brain before birth. Osteocalcin from the bones of pregnant mice can penetrate the placenta and help shape fetal brain development, Karsenty and colleagues reported in 2013 in Cell. What benefit bones get from influencing developing brains remains unclear.

    Another emerging bone messenger is sclerostin. Its day job is to keep bone growth in check by telling bone-forming osteoblasts to slow down or stop. But bones may dispatch the hormone to manage an important fuel source — fat. In mice, the hormone helps convert white (or “bad”) fat into more useful energy-burning beige fat, molecular biologist Keertik Fulzele of Boston University and colleagues reported in the February Journal of Bone and Mineral Research.

    Osteocalcin, sclerostin and LCN2 offer tantalizing clues about bones’ communication skills. Another hormone, fibroblast growth factor 23, or FGF-23, may have more immediate medical applications.

    Bones use FGF-23 to tell the kidneys to shunt extra phosphate that can’t be absorbed. In people with kidney failure, cancer or some genetic diseases, including an inherited form of rickets called X-linked hypophosphatemia, FGF-23 levels soar, causing phosphate levels to plummet. Bones starved of this mineral become weak and prone to deformities.

    In the case of X-linked hypophosphatemia, or XLH, a missing or broken gene in bones causes the hormone deluge. Apprehending the molecular accomplice may be easier than fixing the gene.

    In March, researchers, in collaboration with the pharmaceutical company Ultragenyx, completed the first part of a Phase III clinical trial in adults with XLH [Clinical Research at Yale] — the final test of a drug before federal approval. The scientists tested an antibody that latches on to extra FGF-23 before it can reach the kidneys. Structurally similar to the kidney proteins where FGF-23 docks, the antibody is “like a decoy in the blood,” says Lanske, who is not involved in the trial. Once connected, the duo is broken down by the body.

    Traditionally, treating XLH patients has been like trying to fill a bathtub without a plug. “The kidney is peeing out the phosphorus, and we’re pouring it in the mouth as fast as we can so bones mineralize,” says Suzanne Jan De Beur, a lead investigator of the clinical trial and director of endocrinology at Johns Hopkins Bayview Medical Center. Success is variable, and debilitating side effects often arise from long-term treatment, she says. The antibody therapy should help restore the body’s ability to absorb phosphate.

    Unpublished initial results indicate that the antibody works. Of 68 people taking the drug in the trial, over 90 percent had blood phosphate levels reach and stay in the normal range after 24 weeks of treatment, Ultragenyx announced in April. People taking the antibody also reported less pain and stiffness than those not on the drug.

    Osteocalcin, sclerostin and LCN2 might also be involved in treating diseases someday, if results in animals apply to people.

    In the study recently published in Nature, Kousteni’s team found that boosting LCN2 levels in mice missing the LCN2 gene tamed their voracious feeding habits. Even in mice with working LCN2 genes, infusions of the hormone reduced food intake, improved blood sugar levels and increased insulin sensitivity.

    Researchers traced the hormone’s path from the skeleton to the hypothalamus — a brain structure that maintains blood sugar levels and body temperature and regulates other processes. Injecting LCN2 into mice’s brains suppressed appetite and decreased weight gain. Once the hormone crosses the blood-brain barrier and reaches the hypothalamus, it attaches to the surface of nerve cells that regulate appetite, the team proposed.

    Mice with defective LCN2 docking stations on their brain cells, however, overate and gained weight just like mice that couldn’t make the hormone in the first place. Injections of LCN2 didn’t curb eating or weight gain.

    (Two mouse studies by another research group published in 2010, however, found that LCN2 had no effect on appetite. Kousteni and colleagues say that inconsistency could have resulted from a difference in the types of mice that the two groups used. Additional experiments by Kousteni’s lab still found a link between LCN2 and appetite.)

    In a small group of people with type 2 diabetes, those who weighed more had less LCN2 in their blood, the researchers found. And a few people whose brains had defective LCN2 docking stations had higher blood levels of the hormone.

    If the hormone suppresses appetite in people, it could be a great obesity drug, Rosen says. It’s still too early, though, to make any definitive proclamations about LCN2 and the other hormones’ side hustles, let alone medical implications. “There’s just all sorts of things that we are uncovering that we’ve ignored,” Rosen says. But one thing is clear, he says: The era of bone as a silent bystander is over.

    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.

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  • richardmitnick 8:23 pm on June 9, 2017 Permalink | Reply
    Tags: , ‘Liquid’ properties of light emerge under special circumstances, , Photons, , , Science News, Superfluid Motion of Light Observed at Room Temperature, Superfluidity, Wave nature of light   

    From Science News: “Superfluid Motion of Light Observed at Room Temperature” 

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    Science News

    Jun 9, 2017
    No writer credit found

    An international team of physicists has experimentally demonstrated that superfluid motion of light is possible under ambient conditions. Until now, this phenomenon had only been observed at low cryogenic temperatures.

    1
    Schematic of the organic microcavity used to observe superfluid flow. Image credit: Polytechnique Montreal.

    The wave nature of light has been known for centuries. The fact that light can also behave as a liquid, rippling and spiraling around obstacles, is a much more recent finding.

    The ‘liquid’ properties of light emerge under special circumstances, when the photons that form the light wave are able to interact with each other.

    Physicists from CNR NANOTEC Institute of Nanotechnology in Italy, Polytechnique Montreal in Canada, Aalto University in Finland and Imperial College London in the UK have shown that for light ‘dressed’ with electrons, an even more dramatic effect occurs: light become superfluid, showing frictionless flow when flowing across an obstacle and reconnecting behind it without any ripples.

    “Superfluidity is an impressive effect, normally observed only at temperatures close to absolute zero (minus 273 degrees Celsius), such as in liquid helium and ultracold atomic gasses,” said co-lead author Dr. Daniele Sanvitto, from CNR NANOTEC Institute of Nanotechnology.

    “The extraordinary observation in our work is that we have demonstrated that superfluidity can also occur at room temperature, under ambient conditions, using light-matter particles called polaritons.”

    “Superfluidity, which allows a fluid in the absence of viscosity to literally leak out of its container, is linked to the ability of all the particles to condense in a state called a Bose-Einstein condensate.”

    “Something similar happens, for example, in superconductors: electrons, in pairs, condense, giving rise to superfluids or super-currents able to conduct electricity without losses.”

    2
    The flow of polaritons (quasiparticles that result from a coupling between photons and electron-hole pairs in a semiconductor material) encounters an obstacle in the supersonic (top) and superfluid (bottom) regime. Image credit: Polytechnique Montreal.

    “To achieve superfluidity at room temperature, we sandwiched an ultrathin film of organic molecules between two highly reflective mirrors,” explained Dr. Stéphane Kéna-Cohen, of Polytechnique Montreal.

    “Light interacts very strongly with the molecules as it bounces back and forth between the mirrors and this allowed us to form the hybrid light-matter fluid.”

    “In this way, we can combine the properties of photons such as their light effective mass and fast velocity, with strong interactions due to the electrons within the molecules.”

    “Under normal conditions, a fluid ripples and whirls around anything that interferes with its flow. In a superfluid, this turbulence is suppressed around obstacles, causing the flow to continue on its way unaltered.”

    The researchers said: “the fact that such an effect is observed under ambient conditions can spark an enormous amount of future work, not only to study fundamental phenomena related to Bose-Einstein condensates with table-top experiments, but also to conceive and design future photonic superfluid-based devices where losses are completely suppressed and new unexpected phenomena can be exploited.”

    The research is published in the journal Nature Physics.

    See the full article here .

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  • richardmitnick 10:07 am on April 5, 2015 Permalink | Reply
    Tags: , , Science News,   

    From Science News: “Plate loss gave chain of Pacific islands and seamounts a bend” 

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    ScienceNews

    March 31, 2015
    Thomas Sumner

    1
    SHARP TURN The sharp bend in the Hawaiian-Emperor seamount chain formed after a sinking tectonic plate redirected the mantle flowing underneath the Pacific Ocean, new research suggests.

    The disappearance of a tectonic plate into Earth’s interior may be responsible for the distinctive bend in the chain of underwater mountains and islands that includes the Hawaiian archipelago.

    2
    The tectonic plates of the world were mapped in the second half of the 20th century.

    A reconstruction of the mantle flowing under the Pacific Ocean about 50 million years ago suggests that the submergence of the Izanagi Plate near East Asia reversed the flow’s direction. This mantle U-turn could have immobilized the mantle-dwelling plume of magma that built the mountain ranges, the researchers report online March 24 in Geophysical Research Letters. The abrupt stop probably caused the roughly 120-degree kink in the Hawaiian-Emperor seamount chain as Earth’s crust moved westward over the plume, they conclude.

    Scientists had previously thought a sudden shift in the Pacific Plate’s movements over the magma-spewing hot spot produced the bend where the Emperor undersea mountain range connects to the Hawaiian one. In a related paper published online March 27 in Geology, researchers calculate that the plate didn’t significantly alter course around the time the seamount chain got bent.

    The two findings together suggest that the bend’s initial origin story was off the mark, says geodynamicist Lijun Liu of the University of Illinois at Urbana-Champaign. “These two papers might actually resolve this longstanding debate,” he says. “These are two powerful, independent pieces of evidence that the Hawaiian-Emperor bend is an indication of a deep mantle process, rather than a surface plate motion.”

    The Hawaiian hot spot is a tube-shaped plume in the mantle that carries magma from near Earth’s core to the surface. Over more than 80 million years, molten rock from the hot spot built up a mountain range of islands and underwater seamounts stretching more than 5,800 kilometers across the Pacific Ocean. The seamount chain grew south at first before abruptly turning east around 50 million years ago.

    About 10 million years before the seamount chain took a turn, a tectonic plate off the coast of East Asia met its doom. The Izanagi Plate completely slipped under another plate and into the mantle. Geodynamicist Maria Seton of the University of Sydney and colleagues wondered how the plate’s plunge impacted the movement of mantle beneath the Earth’s surface. Prior to the plate’s demise, the sinking rocky slab had acted like a wall in the mantle layer, obstructing the mantle flow.

    Simulating the interactions between the mantle and the sinking plate, the researchers calculated that removal of the mantle-blocking Izanagi Plate triggered a 7-million-year reorganization of mantle movements beneath the Pacific. Mantle flows did an about-face in the simulation, switching from a southward flow at a rate of 0.5 to 1.7 centimeters per year to a slower northeastward flow of 0.1 to 1.1 centimeters per year. Because the Hawaiian hot spot sits within the mantle, the reversed mantle flow halted the hot spot’s southward drift but wasn’t strong enough to push it northeastward. The hot spot remained stationary as the Pacific Plate drifted westward over it. As a result, the Hawaiian seamount chain expanded to the east.

    In the separate study, geoscientist Nicky Wrightof the University of Sydney and colleagues including Seton used geological data to retrace the Pacific Plate’s movements going back tens of millions of years. They show that while the Izanagi Plate’s disappearance ultimately caused the Pacific Plate to shift more westward, this process was too slow to account for the sharp Hawaiian-Emperor bend.

    “For the longest time scientists assumed that this prominent bend formed because the Pacific Plate changed direction,” says geophysicist Dietmar Müller of the University of Sydney, who coauthored both studies. “We now can demonstrate that the mantle, not the plate, changed its direction of motion.”

    See the full article here.

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  • richardmitnick 9:08 am on March 24, 2015 Permalink | Reply
    Tags: , , Science News, Solo planets   

    From Science News: “Solo planets may be surprisingly common” 

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    ScienceNews

    March 20, 2015
    Ashley Yeager

    1
    GOING ROGUE A disk of gas and dust swirls around OTS 44, a rogue planet shown in this artist’s illustration. It may have formed the same way stars are made.

    Out among the stars, toward the constellation Capricornus, a red sphere floats freely through space. It doesn’t have enough mass to fuse atoms for fuel, as stars do, and it’s too small to be a failed star. In nearly every way, this drifter, known as PSO J318.5-22, is like a planet. Except it fails one key test for planethood: It does not orbit a star.

    7
    PSO J318.5-22 from Pan-STARRS PS1 telescope, Haleakalā

    Pann-STARSR1 Telescope
    Pann-STARRS1 interior
    Pan-STARRS PS1 telescope

    PSO J318.5-22 is homeless. With no parent star to give it heat or light, it drifts in eternal darkness, a rogue of the Milky Way.

    Computer simulations in the 1970s gave planetary scientists their first hints that rogue planets might exist. As planets formed around a star, some planetary material would have been scattered into far-flung orbits. A few miniplanets may have been tossed far enough to be ejected completely from the star’s gravitational grasp.

    Later estimates suggested that every planetary system in the galaxy booted at least one planet into interstellar space. With billions of planetary systems in the Milky Way, there may be billions, maybe even hundreds of billions, of rogue planets in the galaxy, says planetary scientist Sara Seager of MIT.

    The first actual observations of what appeared to be free-floating planets came in 2000, suggesting that the simulations were on to something. In the last 15 years, astronomers have stumbled upon about 50 of these planetlike worlds. Some have all the characteristics of planets, minus a parent star. Others raise questions about how stars and planets can form. They all appear to challenge the standard definition of a planet.

    It’s time to go beyond serendipitous discoveries, says Michael Liu of the University of Hawaii in Honolulu. He would like to see a systematic search for other untethered worlds.

    “A census of rogues,” Liu says, “is the only way we are going to fully understand the extent of what’s out there in the Milky Way.”

    Isolated giants

    Liu and his colleagues first spotted PSO J318.5-22 in 2010; they confirmed and reported the finding in 2013 (SN Online: 10/9/13).

    The researchers detected the planet in images taken with the Maui-based Pan-STARRS 1 telescope. The team had been looking for failed stars called brown dwarfs, which appear to start their lives in the same way stars do: A clump of gas breaks free from a cloud of cold, dense gas and collapses, pulling material inward into a swirling disk around it. At the center of this disk is a baby star or, depending on the size of the original gas clump, a brown dwarf.

    Two traits distinguish a star from a brown dwarf and to an extent, from a planet: mass and the presence or absence of nuclear fusion. Stars, even small ones, are at least 80 times the mass of Jupiter, which at 318 times the mass of Earth is the most massive planet in the solar system — and is often used by astronomers to gauge the size of other gaseous objects. According to theoretical calculations about how stars work, objects must be 80 Jupiter masses or more to fuse hydrogen nuclei (protons) into helium. This process liberates energy, which is how stars burn bright, speckling the night sky.

    Brown dwarfs are smaller, anywhere between 13 and 80 Jupiter masses. They are not dense enough to fuse hydrogen. But they may have been big and hot enough to fuse deuterium nuclei (a proton plus a neutron) with protons or other nuclei, which means they once generated energy but no longer do.

    Any sphere less than about 13 Jupiter masses is not large or dense enough to fuse any kind of atomic nuclei. As a result, some astronomers define orbs with less than roughly 13 Jupiter masses — even untethered ones — as planets.

    2
    3
    4
    Sources: Joergens et al/arXiv.org 2014; Liu et al/ApJ Letters 2013; Luhman et al/ApJ Letters 2014; Delorme et al/A&A 2012; Bennett et al/arXiv.org 2013.

    This has been a point of contention in the astronomy community. When astronomers started reporting free-floating planetary mass objects in 2000, they dubbed them “isolated giant planets.” That simple description set off a heated debate about whether the free‑floaters should be bestowed planethood. In 2003, the International Astronomical Union — the same organization that demoted Pluto to a dwarf planet — weighed in. The IAU said planets orbit the sun. Period. Planets that orbit other stars are extrasolar planets, or exoplanets, and rogues with planetary masses that do not orbit a star are not planets; they are sub–brown dwarfs.

    The IAU’s definitions drew a clear dividing line between stars, brown dwarfs, sub–brown dwarfs and planets. But in reality, Liu says, the galaxy’s contents are much more complicated.

    Around the time of the IAU announcement, Liu joined the hunt for brown dwarfs and exoplanets. In fact, when he and his team first spotted PSO J318.5-22, they thought it might be a brown dwarf. But it was “like nothing we’d seen before,” he says. It was dim and extremely red, redder than any brown dwarf. A closer inspection with larger telescopes confirmed that the object was more like a planet. PSO J318.5-22 is about 6.5 times the mass of Jupiter — well within the size range of a planet. Its color, brightness, atmosphere and mass are also similar to those of the young, dusty exoplanets that orbit the nearby star HR 8799 (SN: 4/6/13, p. 5), the team reported in 2013 in the Astrophysical Journal Letters.

    Rogues are hard to see for two reasons: their lack of a parent star and their size. Planets in orbit tug on their parent star or block its light, which gives clues that the planet exists. This is how the Kepler space telescope and others find far-off worlds.

    NASA Kepler Telescope
    NASA/Kepler

    And because rogues are small, they don’t give off a lot of heat and light compared with stars, which makes them faint and easy to miss with infrared and optical telescopes.

    Despite these challenges, Liu and other astronomers have found about 40 planetlike rogues using infrared and optical telescopes. These instruments are pretty good at spotting larger rogues, but they tend to miss smaller, Earth-sized ones. That’s where gravitational microlensing comes in. A massive object can act as a gravitational magnifying glass, bending and brightening the light of a background star that happens to lie directly behind it as seen from Earth.  About a dozen rogues have been identified with microlensing.

    Violent and messy

    Mass isn’t everything when determining whether an object is a star or a planet. What really matters, says Kevin Luhman of Penn State, is how the rogue was created.

    Based on computer simulations, astronomers suggest two scenarios for how rogues are made: They either got kicked out of a planetary system early on, or they formed just like stars but on a smaller scale.

    The formation of planetary systems is extremely chaotic. It starts with a glob of gas and dust that breaks away from a much larger cloud containing material to support the start-up of many stars. As the glob pulls away, gravity forces everything toward its center. The center becomes more and more compressed, gets hotter and becomes the beginnings of a newborn star. Chunks of rock, ice and dust start to swirl around this stellar kernel. The chunks stick together to form boulders and then continue to grow bigger into planets. These planets can get pulled in toward the star and then pushed farther out.

    As the planets jockey for position, they play a violent and messy game of ping-pong with others around them. In the end, there’s not enough gravity to keep all the planets circling the parent star. One or more get knocked into space, according to this scenario, and rogue planets are born.

    There’s evidence of this kind of roughhousing even within our own solar system (SN: 3/21/15, p. 14), Seager says.

    The first hint of these shenanigans came from the Oort cloud, a swarm of trillions of ice chunks tethered to the sun by gravity (SN: 10/19/13, p. 19).

    Oort Cloud
    Oort cloud

    The Oort cloud, which extends to the farthest edges of the solar system, forms a bubble of debris around the sun and its planets. It is probably made of rubble that was thrown out of the inner solar system as the planets took their places about 4 billion years ago, Seager says.

    In order for Jupiter, Saturn, Uranus and Neptune to be orbiting where they are today, some simulations suggest, there was probably a fifth planet bouncing around with them at some point (SN: 5/5/12, p. 24). Jupiter eventually booted the hypothetical planet, with a mass similar to Neptune’s, into interstellar space, researchers from the Southwest Research Institute reported in 2011.

    Not what, but how

    Planetary ping-pong may not be the only way rogues are made, says astronomer Gösta Gahm of Stockholm University. He argues that planets may form without parent stars. Perhaps they form exactly the way stars do in the same regions of space, only on a much smaller scale. In stellar nurseries, big globs of gas and dust become stars. In Gahm’s theory, a glob of gas and dust, which can be just a few times the mass of Jupiter, can collapse and condense into a planet — a free-floating planet rather than a star or brown dwarf.

    Gahm has detected hundreds of potential planet-forming gas and dust globs, called globulettes, in the Carina nebula, he and Tiia Grenman of Luleå University of Technology in Sweden reported in Astronomy & Astrophysics in May 2014.

    7
    Detail of NGC 3372 taken by the ESO/VLT telescope

    ESOVLTI
    ESO VLT Survey telescope
    ESO/VLT

    Gahm and colleagues also found some in the Rosette nebula, as reported in the same journal in 2013.

    Rosette, 5,200 light-years away in the Monoceros constellation, is a low-density cloud of gas at the center of a larger cloud of gas and dust where stars and planetary systems are taking shape. The Rosette nebula contains globulettes that are just starting to break away from larger gas clouds.

    6
    NEBULA NURSERY About 5,200 light-years from Earth, a cloud of gas and dust called the Rosette nebula (shown here) is churning out newborn stars. It may also be giving birth to rogue planets, some scientists say.

    The Carina nebula, which sits about 7,500 light-years away in the constellation Carina, is one of the largest star-forming regions in the sky. It’s a diffuse cloud where stars are forming at a fast pace and where there are a lot of globulettes, some smaller than the mass of Jupiter. These tiny gas globs are smaller and denser than what’s been observed in other nebula, so they are possibly farther along in their path toward becoming free-floating planets, Gahm argues.

    Thomas Haworth, an astrophysicist at the University of Cambridge, is delving deeper into how globulettes might transition from extremely tiny gas clouds to full-fledged free‑floaters. His simulations show that the tiny globs of gas don’t necessarily have enough gravity to collapse in on themselves and condense to form stars. Gahm argues that external pressure from hot gas from nearby new stars or some other turbulence could force the globulettes to condense. But when Haworth includes this type of turbulence in simulations, it’s still not enough to turn globulettes into planets. He and colleagues reported the findings in the January Monthly Notices of the Royal Astronomical Society.

    That doesn’t mean the scenario is wrong, Haworth says. Globulettes could hit the boundary of a cloud where stars are forming, and, with the right amount of oomph, get squashed and collapse into a planet or brown dwarf, he says. He is working on simulations of this scenario and a few others.

    “Globulettes are very numerous,” he says. “Even if only a small fraction can be made to collapse, they could make a significant contribution to the population of free-floating planets.”

    One directly imaged free-floater, a rogue called OTS 44, appears to support Gahm’s globulette theory. Astronomers estimate that OTS 44’s mass is right around 12 Jupiter masses, at the high end of the mass of a planet. And it’s about 2 million years old — a newborn in the cosmic sense. OTS 44 also has a ring of gas and dust around it, and like a star, the gassy rogue is pulling on this disk of material to build itself up. Astronomers have seen this kind of accretion disk around planets that orbit small stars, but it has never been found around a free-floater before, researchers reported last year at a workshop on cool stars and the sun.

    9
    Image taken by Hubble space telescope of what may be gas accreting onto a black hole in elliptical galaxy NGC 4261

    NASA Hubble Telescope
    NASA/ESA Hubble

    9
    Chandra X-ray Image of NGC 4261. The Chandra image of the elliptical galaxy NGC 4261 reveals dozens of black holes and neutron stars strung out across tens of thousands of light years like beads on a necklace. The spectacular structure, which is not apparent from the optical image of the galaxy, is thought to be the remains of a collision between galaxies a few billion years ago.

    NASA Chandra Telescope
    NASA/Chandra

    10
    A Hubble Space Telescope (HST) image of the gas and dust disk in the active galactic nucleus of NGC 4261. Credit: HST/NASA/ESA.

    The nomad appears to be in an advanced stage along Gahm’s globulette-based path to planethood.

    That finding blurs the line that the IAU and others say separates stars and planets.

    Luhman argues, however, that the formation process of a star is very different from the formation process of a small body within the gas and dust around a much larger object. “It is much more meaningful to distinguish between planets and brown dwarfs based on how they formed,” he says.

    No interference

    For all the problems they pose for scientists, rogue planets do have some benefits. “One of the best things about rogue planets is that they don’t have a blinding parent star to wash out their atmospheres,” Liu says. “Rogues have given us an incredible view of planet composition, and they can tell us about planets that do orbit stars.”

    Comparing the atmospheres of rogue planets with those of brown dwarfs and stars could be the best way to distinguish the types of spheres from each other. Such comparisons could reveal how different free-floaters formed and lend credence to Luhman’s argument that if it formed like a star, it’s a star, and if it formed like a planet, it’s a planet. That kind of detail could require a new definition of the word planet, one that may need to include rogues.

    Sifting through the rogues’ atmospheres could also reveal whether they have signs of life. David Stevenson, a planetary scientist at Caltech, was among the first to argue (in Nature in 1999) that if free-floaters retained their hydrogen atmospheres, they could stay warm enough to have water oceans and possibly harbor life. Others have invoked dark matter to explain how rogues could support life without energy from a nearby star.

    7
    MASS MATTERS Small stars, brown dwarfs and rogue planets can be similar in diameter but have different masses. Mass is one characteristic used to distinguish the objects. However, for classification purposes, astronomers may need to look beyond mass to consider how an orb formed and what elements it’s made of.
    From left: jut13/istockphoto; NASA; Segransan et al/A&A 2008; Leech et al/ASP Conference Series 2000; Liu et al/ApJ Letters 2013

    In this far-out scenario, dark matter, in the form of weakly interacting massive particles, comes in contact with atomic nuclei, loses momentum and gets pulled in by a planet’s gravity. The dark matter particles build up in the planet’s interior, where they bang into and annihilate each other. This interaction creates energetic particles that get absorbed by surrounding material, providing heat to the planet. It could happen at high enough rates to heat the planet to a temperature that keeps liquid water on its surface, even without the help of a parent star’s light, scientists argued in a 2012 paper in the Journal of Cosmology and Astroparticle Physics.

    Seager agrees that it may be possible for rogues to have the right surface conditions for life.

    Finding evidence to support the idea, however, will require a more complete census of rogues, both big and small. PSO J318.5-22’s extreme redness appears to be a signature that astronomers can use to find more, at least the bigger ones. Liu has tried it and may have hit on four or five more free-floaters already, he says. As for the small ones, some may have been spotted indirectly. But taking images of these smaller ones and exploring their atmospheres to look for signs of life is going to require much more powerful telescopes, a few of which are slated to come online in a decade or so.

    “We’re trying to understand the full range of planet systems,” Seager says. Bigger telescopes will help astronomers understand what’s still in a planetary system, what’s been forced out and what else is out there.

    Astronomers may just find that our galaxy is swarming with wandering worlds.

    See the full article here.

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