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  • richardmitnick 11:40 am on December 5, 2019 Permalink | Reply
    Tags: "A newfound black hole in the Milky Way is weirdly heavy", , , , , Gran Telescopio Canarias, , LAMOST telescope in China, Science News, That’s not just a record- it’s also a conundrum., With a mass of about 68 suns it is far heftier than other stellar-mass black holes (those with masses below about 100 suns) in and around the Milky Way scientists say.   

    From Science News: “A newfound black hole in the Milky Way is weirdly heavy” 

    From Science News

    November 27, 2019
    Christopher Crockett

    1

    A black hole (one illustrated) with a mass equal to about 68 suns has been found in the Milky Way, researchers say. That dark mass is much heavier than other similar black holes. NAOJ

    A heavyweight black hole in our galaxy has some explaining to do.

    With a mass of about 68 suns, it is far heftier than other stellar-mass black holes (those with masses below about 100 suns) in and around the Milky Way, scientists say. That’s not just a record, it’s also a conundrum. According to theory, black holes in our galaxy that form from the explosive deaths of massive stars — as this one likely did — shouldn’t be heavier than about 25 suns.

    The black hole is locked in orbit with a young blue star dubbed LB-1, which sits about 13,800 light-years away in the constellation Gemini, researchers found. Combing through data from the LAMOST telescope in China, Jifeng Liu, an astrophysicist at the Chinese Academy of Sciences in Beijing, and colleagues noticed that LB-1 repeatedly moves toward and away from Earth with great speed — a sign that the star orbits something massive.

    LAMOST telescope located in Xinglong Station, Hebei Province, China

    With additional observations from telescopes in Hawaii and the Canary Islands, the team mapped out the orbit and deduced that the star gets whipped around by a dark mass roughly 68 times as massive as the sun. Only a black hole fits that description, the team reports November 27 in Nature.

    Keck Observatory, operated by Caltech and the University of California, Maunakea, Hawaii, USA.4,207 m (13,802 ft), above sea level,

    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

    “I never thought in my wildest dreams you could form a black hole this big [in the Milky Way],” says Michael Zevin, an astrophysicist at Northwestern University in Evanston, Ill. “If the observations pan out to be correct, this is really going to have people scratching their heads.”

    This black hole is not the heftiest in the Milky Way. That title goes to the behemoth in the center of the galaxy, a supermassive black hole in a class all its own with a mass of over 4 million suns. The mass of LB-1’s black hole is, however, on par with some of the black holes discovered recently by gravitational wave detectors, which sense ripples in spacetime from (among other things) merging pairs of black holes (SN: 2/17/16).

    But those black holes formed in far-off galaxies, probably in environments with a relative dearth of elements heavier than helium. The star LB-1 has a richer inventory of those elements, and presumably the star that formed its partner black hole had a similar stock. Stars with a greater abundance of heavy elements lose more of their mass to stellar winds, as those elements present a larger target to the radiation that drives those winds. Massive stars that form black holes also eject a lot of their mass during the supernova explosions that end their lives.

    “These two processes make very small black holes even out of very massive stars,” Liu says. But the black hole near LB-1 apparently didn’t get that memo.

    To make a black hole of 68 solar masses requires a reduction in the mass lost to stellar winds by a factor of five, Liu says. “We don’t know whether this is possible theoretically.”

    Alternatively, the black hole might have emerged from a failed supernova, an attempted stellar explosion that doesn’t have quite enough energy to hurl the star’s guts into space, leaving the gas to fall back into the black hole.

    The team also wonders if the black hole is the work of two stars. The scenario is speculative, Liu says, and “the odds are slim.” But in this story, LB-1 once orbited a snuggled-up pair of heftier stars that died and left behind two cores that merged into one black hole.

    It’s also possible that what appears to be a single 68-solar-mass black hole is actually two lighter black holes locked in a tight embrace. Such a pair would periodically nudge LB-1, giving it a subtle rocking motion that Liu and colleagues are searching for with other telescopes.

    Before getting caught up in potential origin stories, the observations need to be double-checked, Zevin cautions. “I wouldn’t put money down that it’s a definitive detection yet,” he says.

    The one catch, which the researchers do note, is that the calculated mass of the black hole depends on getting the distance to LB-1 correct. Their derived distance of 13,800 light-years — based on the star’s apparent brightness and calculations of its intrinsic luminosity — is about twice as far as the distance to the star determined by the Gaia satellite, a multiyear mission to create a precise 3-D map of over 1 billion stars in the Milky Way (SN: 5/9/18). If the Gaia distance is correct, then the black hole might be only 10 times as massive as the sun. (If the star is closer, then it’s less luminous, so less massive. That would mean that a lighter black hole is needed to explain the speed at which the star is getting whipped around.)

    That’s not necessarily a strike against the study. The researchers note that a much lower luminosity for the star would be at odds with its measured temperature. And if LB-1 is wobbling around a black hole, that would throw off the accuracy of the Gaia data, says Zevin. “But it is an important point that needs to be worked out.”

    See the full article here .


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  • richardmitnick 3:55 pm on November 26, 2019 Permalink | Reply
    Tags: "19 more galaxies mysteriously missing dark matter have been found", , , , , Science News   

    From Science News: “19 more galaxies mysteriously missing dark matter have been found” 

    From Science News

    November 25, 2019
    Christopher Crockett

    1
    Most dwarf galaxies, like NGC 5477 seen in this image from the Hubble Space Telescope, have far more dark matter than normal everyday matter. But researchers recently found 19 dwarf galaxies that seem to be missing huge stores of dark matter. NASA/ESA Hubble

    A smattering of small galaxies appear to be missing a whole lot of dark matter.

    Most of a typical galaxy is invisible. This elusive mass, known as dark matter, seems to be an indispensable ingredient for creating a galaxy — it’s the scaffolding that attracts normal matter — yet reveals itself only as an extra gravitational tug on gas and stars.

    But now, researchers have found 19 dwarf galaxies — all much smaller than the Milky Way — that defy this common wisdom. These newly identified outliers have much less dark matter than expected. The finding, published November 25 in Nature Astronomy, more than quintuples the known population of dark-matter renegades, adding fuel to an already simmering mystery.

    “We are not sure why and how these galaxies form,” says Qi Guo, an astrophysicist at the Chinese Academy of Sciences in Beijing. Typical dwarf galaxies concentrate dark matter far more than their larger cousins, she notes. Their smaller size leads to weaker gravity, which has trouble holding on to tenuous clouds of gas. That usually shifts the balance of mass in dwarf galaxies away from normal matter and toward dark matter.

    “This new class of galaxy is straining our ability to explain all galaxies in one cohesive framework,” says Kyle Oman, an astrophysicist at Durham University in England who was not involved in this research.

    In 2016, Oman and his colleagues identified two galaxies that appeared to be missing dark matter. In short order, two more oddballs turned up (SN: 3/28/18).

    Guo and her colleagues wondered if these galaxies had more company. So using existing data from the Arecibo radio telescope in Puerto Rico, the team weighed dwarf galaxies by looking at how fast hydrogen whipped around each one. Higher speed means more total mass. The researchers then combined the mass of the hydrogen and of all the stars, inferred from starlight, to estimate how much of each galaxy’s mass is made up of normal matter.

    For every galaxy, total mass added up to more than the mass of the gas and stars — not surprising, as that extra mass is the dark matter. But in about 6 percent of cases, there wasn’t as much extra mass as expected.

    One oddball, designated AGC 213086, weighs in at around 14 billion suns. If it were typical, about 2 percent of its mass — nearly 280 million solar masses — would be gas and stars. Instead, its actual inventory of normal matter is about 3.8 billion solar masses, or about 27 percent of its total mass.

    Of 324 dwarf galaxies analyzed, 19 appear to be missing similarly large stores of dark matter. Those 19 are all within about 500 million light-years of Earth, and five are in or near other groups of galaxies. In those cases, the researchers note, perhaps their galactic neighbors have somehow siphoned off their dark matter. But the remaining 14 are far from other galaxies. Either these oddballs were born different, or some internal machinations such as exploding stars have upset their balance of dark matter and everyday matter, or baryons.

    It may not be a case of missing dark matter, says James Bullock, an astrophysicist at the University of California, Irvine. Instead, maybe these dwarf galaxies have clung to their normal matter — or even stolen some — and so “have too many baryons.” Either way, he says, “this is telling us something about the diversity of galaxy formation…. Exactly what that’s telling us, that’s the trick.”

    See the full article here .


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  • richardmitnick 9:25 am on November 17, 2019 Permalink | Reply
    Tags: "Realigning magnetic fields may drive the sun’s spiky plasma tendrils", Science News,   

    From Science News: “Realigning magnetic fields may drive the sun’s spiky plasma tendrils” 

    From Science News

    November 14, 2019
    Christopher Crockett

    1

    Whiskery plasma jets, known as spicules, on the sun appear as dark, threadlike structures in this image, acquired at the Goode Solar Telescope in Big Bear, Calif. T. Samanta, GST & SDO

    1
    The Goode Solar Telescope pointed at the Sun in the morning.
    Date 23 July 201
    Big Bear Solar Observatory
    Location Big Bear Lake, California, US
    Altitude 2,060 m (6,760 ft)

    NASA/SDO

    Tendrils of plasma near the surface of the sun emerge from realignments of magnetic fields and pump heat into the corona, the sun’s tenuous outer atmosphere, a study suggests.

    The new observation, described in the Nov. 15 Science, could help crack the century-plus mystery of where these plasma whiskers, called spicules, come from and what role — if any — they play in heating the corona to millions of degrees Celsius.

    Spicules undulate like a wind-whipped field of wheat in the chromosphere, the layer of hot gas atop the sun’s surface. These plasma filaments stretch for thousands of kilometers and last for just minutes, shuttling ionized gas into the corona. Astronomers have long debated how spicules form — with the sun’s turbulent magnetic field being a prime suspect — and whether they can help explain why the corona is a few hundred times as hot as the sun’s surface (SN: 8/20/17).

    To look for connections between spicules and magnetic activity, solar physicist Tanmoy Samanta of Peking University in Beijing and colleagues pointed the Goode Solar Telescope, at Big Bear Solar Observatory in California, at the sun. They snapped images of spicules forming, while also measuring the surrounding magnetic field. The team discovered that thickets of spicules frequently emerged within minutes after pockets of the local magnetic field reversed course and pointed in the opposite direction from the prevailing field in the area.

    Counterpointing magnetic fields create a tension that gets resolved when the fields break and realign, and the team postulates that the energy released in this “magnetic reconnection” creates the spicules. “The magnetic field energy is converted to kinetic and thermal energy,” says study coauthor Hui Tian, a solar physicist also at Peking University. “The kinetic energy is in the form of fast plasma motion — jets, or spicules.”

    To see if this energy made it into the corona, the team pored through images acquired at the same time by NASA’s orbiting Solar Dynamics Observatory. Those data revealed a glow from charged iron atoms directly over the spicules. That glow, Tian says, means the plasma reached roughly 1 million degrees Celsius. Whether that’s enough to sustain the scorching temperature throughout the corona, however, remains to be seen.

    “Their observations are amazing,” says Juan Martínez-Sykora, a solar physicist at the Lockheed Martin Solar & Astrophysics Laboratory in Palo Alto, Calif.

    Capturing this level of detail is difficult, Martínez-Sykora says, because individual spicules are relatively small and come and go so quickly. He does caution, though, that the magnetic reconnection story needs to be checked with computer simulations or more observations. As it stands, it remains a postulation, he says.

    See the full article here .


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  • richardmitnick 11:26 am on November 10, 2019 Permalink | Reply
    Tags: , By watching how atoms behave when they’re suspended in midair rather than in free fall physicists have come up with a new way to measure Earth’s gravity., , Physicists split atoms into a weird quantum state called superposition — where one version of the atom is slightly higher than the other., , , Science News   

    From Science News: “Trapping atoms in a laser beam offers a new way to measure gravity” 

    From Science News

    November 7, 2019
    Maria Temming

    The technique can measure slight gravitational variations, which could help in mapping terrain.

    1
    A new type of experiment to measure the strength of gravity uses atoms suspended in laser light (with the machinery pictured above), rather than free-falling atoms. V. Xu.

    By watching how atoms behave when they’re suspended in midair, rather than in free fall, physicists have come up with a new way to measure Earth’s gravity.

    Traditionally, scientists have measured gravity’s influence on atoms by tracking how fast atoms tumble down tall chutes. Such experiments can help test Einstein’s theory of gravity and precisely measure fundamental constants (SN: 4/12/18). But the meters-long tubes used in free-fall experiments can be unwieldy and difficult to shield from environmental interference such as stray magnetic fields. With a new tabletop setup, physicists can gauge the strength of Earth’s gravity by monitoring atoms suspended a couple millimeters in the air by laser light.

    This redesign, described in the Nov. 8 Science, could better probe the gravitational forces exerted by small objects. The technique also could be used to measure slight gravitational variations at different places in the world, which may help in mapping the seafloor or finding oil and minerals underground (SN: 2/12/08).

    Physicist Victoria Xu and colleagues at the University of California, Berkeley began by launching a cloud of cesium atoms into the air and using flashes of light to split each atom into a superposition state. In this weird quantum limbo, each atom exists in two places at once: one version of the atom hovering a few micrometers higher than the other. Xu’s team then trapped these split cesium atoms in midair with light from a laser.

    3
    Got you, atom. To measure gravity, physicists split atoms into a weird quantum state called superposition — where one version of the atom is slightly higher than the other (blue dots connected by vertical yellow bands in this illustration). The researchers trap these atoms in midair using laser light (horizontal blue bands). While held in the light, each version of a single atom behaves slightly differently, due to their different positions in Earth’s gravitational field. Measuring those differences allows physicists to determine the strength of Earth’s gravity at that location.

    Measuring the strength of gravity with atoms that are held in place, rather than being tugged downward by a gravitational field, requires tapping into the atoms’ wave-particle duality (SN: 11/5/10). That quantum effect means that, much as light waves can act like particles called photons, atoms can act like waves. And for each cesium atom caught in superposition, the higher version of the atom wave undulates a little faster than its lower counterpart, due to the atoms’ slightly different positions in Earth’s gravitational field. By tracking how fast the waviness of the two versions of an atom gets out of sync, physicists can calculate the strength of Earth’s gravity at that spot.

    “Very impressive,” says physicist Alan Jamison of MIT. To him, one big promise of the new technique is more controlled measurements. “It’s quite a challenge to work on these drop experiments, where you have a 10-meter-long tower,” he says. “Magnetic fields are hard to shield, and the environment produces them all over the place — all the electrical systems in your building, and so forth. Working in a smaller volume makes it easier to avoid those environmental noises.”

    More compact equipment can also measure shorter-range gravity effects, says study coauthor Holger Müller. “Let’s say you don’t want to measure the gravity of the entire Earth, but you want to measure the gravity of a small thing, such as a marble,” he says. “We just need to put the marble close to our atoms [and hold it there]. In a traditional free-fall setup, the atoms would spend a very short time close to our marble — milliseconds — and we would get much less signal.”

    Physicist Kai Bongs of the University of Birmingham in England imagines using the new kind of atomic gravimeter to investigate the nature of dark matter or test a fundamental facet of Einstein’s theory of gravity called the equivalence principle (SN: 4/28/17). Many unified theories of physics proposed to reconcile quantum mechanics and Einstein’s theory of gravity — which are incompatible — violate the equivalence principle in some way. “So looking for violations might guide us to the grand unified theory,” he says. “That’s one of the Holy Grails in physics.”

    See the full article here .


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  • richardmitnick 10:54 am on November 10, 2019 Permalink | Reply
    Tags: "Light leaking from a distant galaxy hints at a cosmic makeover’s origins", , , , , Science News, Sunburst Arc galaxy   

    From Science News: “Light leaking from a distant galaxy hints at a cosmic makeover’s origins” 

    From Science News

    November 7, 2019
    Christopher Crockett

    Harsh ultraviolet radiation suggests how hydrogen got ionized in the universe long ago.

    1
    Visible and infrared light shine from a single star-forming region in the Sunburst Arc galaxy (center). The spot of light is duplicated six times in the arc in this Hubble Space Telescope image, thanks to the gravity of a separate galaxy cluster (not shown). T.E. Rivera-Thorsen, Hubble Space Telescope.

    A leaky galaxy might be offering up clues about a vast cosmic makeover foisted on the universe during its youth.

    Within about a billion years after the Big Bang, something stripped nearly all of the hydrogen atoms in the universe of their electrons. This “reionization” puzzles astronomers, who can’t account for all of the energy needed to make such a sweeping change (SN: 2/6/17).

    A galaxy dubbed the Sunburst Arc might help. It appears to be blasting ionizing ultraviolet radiation through a small hole (or holes) carved out of the gas that permeates the galaxy, researchers report in the Nov. 8 Science. Similar channels in the earliest generation of galaxies could have provided an escape hatch for harsh light to zap intergalactic hydrogen.

    While massive youthful stars can produce ionizing radiation, the light has trouble navigating the thickets of gas and dust within the host galaxy. “Not all of it can get outside the galaxy, let alone reionize the intergalactic medium,” says Brant Robertson, an astronomer at the University of California, Santa Cruz, who was not involved with the research. And yet, get out it must, given what happened to the cosmic inventory of hydrogen.

    Directly looking for ionizing radiation from the first galaxies is out of the question. Intervening gas clouds absorb that faint light long before it reaches Earth. “The way to go about it is to look for [closer] analogs,” says Joanna Bridge, an astronomer at the University of Louisville in Kentucky also not a part of this study. “We look for galaxies that are similar … and gain an understanding of the physical processes that might have occurred.”

    2
    Ionizing radiation blasts out of a single spot in the Sunburst Arc galaxy, made visible here using a special filter on the Hubble Space Telescope. The six spots of light are all from the same source, and are distorted and replicated thanks to the gravity of an intervening galaxy cluster (not shown).T.E. Rivera-Thorsen, Hubble Space Telescope.

    Meet the Sunburst Arc, a galaxy in the small southern constellation Apus whose light takes nearly 11 billion years to reach Earth — far, but not quite as far as the galaxies responsible for reionization. Part of what makes the Sunburst Arc special is that it hides behind a much closer cluster of galaxies. The gravity from that cluster amplifies and smears the Sunburst Arc’s light into an arc — hence its nickname — creating 12 distorted images of the galaxy smeared across the sky.

    Without this gravitational assist, “we probably would not have noticed it,” says Thøger Emil Rivera-Thorsen, an astronomer at Stockholm University. “It would have been just one more speck out of millions.”

    Two years ago, Rivera-Thorsen and colleagues noticed that a particular wavelength of ultraviolet light from this galaxy appeared to sneak out through small gaps in its hydrogen gas [Astronomy and Astrophysics], like water through a sieve. This light is not energetic enough to ionize hydrogen. But through those gaps, the team hypothesized, more energetic ionizing light might slip out as well.

    To test their idea, the team pointed the Hubble Space Telescope at the Sunburst Arc. In all 12 of the gravitationally distorted images, the researchers saw ultraviolet light capable of ionizing hydrogen blasting out of a small region within the galaxy. The source of the ultraviolet light coincides with a splotch of bright light seen in previous Hubble images, light that the team suspects radiates from a pocket of intense star formation no more than about 520 light-years across. The scientists think that the ionizing radiation from these young stars is using one or a few holes in the surrounding gas to escape into intergalactic space.

    “This object is a unique lab for understanding the detailed way in which ionizing photons get out of a galaxy,” Robertson says. The find is also reminiscent of another much closer galaxy, where a few years ago astronomers reported a similar leak of ionizing light (SN: 10/10/14).

    Whether this actually is a missing piece in the reionization puzzle remains to be seen. “In the part of the universe we studied, this is an atypical galaxy,” Rivera-Thorsen says. Out of hundreds of thousands the team has looked at, no other galaxy appears to behave this way. Whether such open pathways in the gas were more common in earlier galaxies is unknown. “That’s still an open question,” he says.

    See the full article here .


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  • richardmitnick 12:05 pm on October 29, 2019 Permalink | Reply
    Tags: "Rules guarding other planets from contamination may be too strict", , , , , Science News, Spacecraft landing in areas deemed sterile could still contaminate areas that are potentially interesting for astrobiology says John Rummel of the SETI Institute., That’s the conclusion of a 12-expert panel commissioned by NASA to review voluntary international guidelines for keeping space missions from polluting other worlds with earthly life and vice versa., The review panel also recommended reassessing contamination risks across Mars.   

    From Science News: “Rules guarding other planets from contamination may be too strict” 

    10.29.19
    Maria Temming

    As more missions target the moon, Mars and other places, scientists want to update guidelines.

    1
    Given what we know now about solar system bodies like the moon and Mars, future space missions may not need to abide by the same, strict planetary protection guidelines currently used, scientists say. NASA

    Some policies for protecting the moon, Mars and other places in the solar system from contamination by visiting missions may be too strict.

    That’s the conclusion of a 12-expert panel commissioned by NASA to review voluntary international guidelines for keeping space missions from polluting other worlds with earthly life, and vice versa. These guidelines are recommendations from the international scientific organization COSPAR, which for decades has set and revised policies for spacefaring nations (SN: 1/10/18).

    With NASA sending a sample-collection mission to Mars next year (SN: 11/19/18), and other government agencies and private companies also preparing for trips to the moon (SN: 11/11/18), planetary protection guidelines “are in urgent need of updating,” said Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, in a teleconference coinciding with the review’s October 18 release. “We want to respect the integrity of the places we go and protect our home planet” from any contaminants that might be brought back, he says. But the report found that current rules could make future missions unnecessarily complex or expensive.

    For instance, current guidelines treat the whole moon as a potentially interesting site to investigate the origins of life. That means every landing mission is supposed to submit documentation to COSPAR detailing where it went and what it did. But apart from a few regions, such the lunar south pole which may have water ice reservoirs (SN: 7/22/19), the moon holds little interest for investigating the chemical evolution of life, said panel chair and planetary scientist Alan Stern of the Southwest Research Institute in Boulder, Colo., during the teleconference. So many places may not need protection.

    At least one astrobiologist cautioned, however, against relaxing current guidelines too much. Spacecraft landing in areas deemed sterile could still contaminate areas that are potentially interesting for astrobiology, says John Rummel of the SETI Institute in Mountain View, Calif. If a lunar probe crashes on the moon’s surface, “you end up with material that’s taken into the lunar atmosphere and deposited in the cold traps at the south and north anyway,” he says. “You don’t even have to land at the south pole to affect [it].”

    3
    It might be time to rethink the rules on how clean spacecraft need to be to visit Mars (pictured), as well as how dangerous Red Planet rocks brought back home would really be, according to a new NASA report.Cornell Univ., JPL-NASA

    In its report, the review panel also recommended reassessing contamination risks across Mars. Missions to the Red Planet have been designed to meet rigorous sterilization standards that often involve exposing spacecraft components to heat, chemicals or harsh radiation. But experiments have suggested that Earth microbes probably would struggle to survive and spread on many parts of Mars. So such deep cleaning may not be needed, according to the report.

    The report suggests that specific areas of Mars should be identified as high-priority zones for seeking past or present life. Other areas could be designated as human exploration zones, where microbes brought by astronauts wouldn’t pose such a problem. “While some places on Mars have high interest for understanding the potential for past life on Mars, or even prebiotic development of life … not all places on Mars have that potential,” Stern said.

    Astrobiologist Alberto Fairén of Cornell University welcomes the possibility of adding nuance to the “extremely restrictive” protection guidelines for Mars. He and colleagues recommended a few high-priority astrobiology zones in Advances in Space Research in March, including lakes of liquid water possibly hidden under ice sheets (SN: 12/17/18).

    Rummel, of the SETI Institute, takes a more conservative view. “There are undoubtedly places on Mars where Earth microbes aren’t going to grow,” he says. The rub is understanding Mars in enough detail to know where those spots are with total confidence. “We don’t know enough about Mars, in my opinion, [to categorize] most of it.”

    Beyond reevaluating the risks of contaminating the Martian surface, the NASA report also considers rules for bringing samples back to Earth. Current guidelines stipulate that Red Planet rocks should be sterilized or to undergo biohazard testing before they can be handed out for analysis. Such precautions “lack a fully rational basis,” considering how much Martian material has landed already on Earth, the report says. “Earth and Mars have been exchanging meteorites for billions of years with absolutely no planetary protection,” Stern pointed out.

    NASA now will consider the report in updating its own standards of practice for planetary protection, but the process for incorporating these suggestions into COSPAR’s guidelines “is not well-defined,” the report says.

    See the full article here .


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  • richardmitnick 9:14 am on October 17, 2019 Permalink | Reply
    Tags: "Physicists have found quasiparticles that mimic hypothetical dark matter axions", , , If axions exist as fundamental particles they could constitute a hidden form of matter in the cosmos- dark matter., Science News, The axions analogs within the crystal are a type of quasiparticle a disturbance in a material that can mimic fundamental particles like axions., The new study reveals for the first time that the phenomenon has a life beyond mere equations., , Within a crystal a wave of varying density of electromagnetic charge forms. When that wave slides back and forth it is mathematically equivalent to an axion.   

    From Science News: “Physicists have found quasiparticles that mimic hypothetical dark matter axions” 

    From Science News

    October 15, 2019
    Emily Conover

    1
    Scientists have spotted a solid matter analog to hypothetical subatomic particles called axions. Within a crystal, a wave of varying density of electromagnetic charge forms. When that wave slides back and forth, it is mathematically equivalent to an axion. sesame/DigitalVision Vectors/Getty.

    An elusive hypothetical particle comes in imitation form.

    Lurking within a solid crystal is a phenomenon that is mathematically similar to proposed subatomic particles called axions, physicist Johannes Gooth and colleagues report online October 7 in Nature.

    If axions exist as fundamental particles, they could constitute a hidden form of matter in the cosmos, dark matter. Scientists know dark matter exists thanks to its gravitational pull, but they have yet to identify what it is. Axions are one possibility, but no one has found the particles yet (SN: 4/9/18).

    Enter the imitators. The axions analogs within the crystal are a type of quasiparticle, a disturbance in a material that can mimic fundamental particles like axions. Quasiparticles result from the coordinated jostling of electrons within a solid material. It’s a bit like how birds in a flock seem to take on new forms by syncing up their movements.

    Axions were first proposed in the context of quantum chromodynamics — the theory that explains the behaviors of quarks, tiny particles that are contained, for example, inside protons. Axions and their new doppelgängers “are mathematically similar but physically totally unrelated,” says theoretical physicist Helen Quinn of SLAC National Accelerator Laboratory in Menlo Park, Calif., one of the scientists who formulated the theory behind axions. That means scientists are no closer to solving their dark matter woes.

    Still, the new study reveals for the first time that the phenomenon has a life beyond mere equations, in quasiparticle form. “It’s actually amazing,” says Gooth, of the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany. The idea of axions is “a very mathematical concept, in a sense, but it still exists in reality.”

    In the new study, the researchers started with a material that hosts a type of quasiparticle known as a Weyl fermion, which behaves as if massless (SN: 7/16/15). When the material is cooled, Weyl fermions become locked into place, forming a crystal. That results in the density of electrons varying in a regular pattern across the material, like a stationary wave of electric charge, with peaks in the wave corresponding to more electrons and dips corresponding to fewer electrons.

    Applying parallel electric and magnetic fields to the crystal caused the wave to slosh back and forth. That sloshing is the mathematical equivalent of an axion, the researchers say.

    To confirm that the sloshing was occurring, the team measured the electric current through the crystal. That current grew quickly as the researchers ramped up the electric field’s strength, in a way that is a fingerprint of axion quasiparticles.

    If the scientists changed the direction of the magnetic field so that it no longer aligned with the electric field, the enhanced growth of the electric current was lost, indicating that the axion quasiparticles went away. “This material behaves exactly as you would expect,” Gooth says.

    See the full article here .


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  • richardmitnick 12:16 pm on October 3, 2019 Permalink | Reply
    Tags: , Monika Schleier-Smith, , Science News   

    From Science News: “Monika Schleier-Smith leads elaborate quantum conversations” 

    From Science News

    October 2, 2019
    Elizabeth Quill

    The fussy experimental work could be a boon for timekeeping and computing.

    “I like it if I can run uphill and be rewarded with a view of the bay,” says Monika Schleier-Smith.

    1
    Monika Schleier-Smith combines persistence and clarity of vision to do impressive experimental work. Dawn Harmer/SLAC National Accelerator Laboratory.

    She’s talking about a favorite spot to exercise around Palo Alto, Calif., but the sentiment also applies to her scientific work. A physicist at Stanford, Schleier-Smith, 36, has a reputation for embracing the uphill climb. She’ll push, push, push the smallest details of an experiment until she achieves what others thought near impossible.

    Her reward? Seeing large ensembles of atoms do her bidding and interact with one another over distances that are incredibly vast, at least for the quantum realm.

    “She tends to persist,” says Harvard physicist Susanne Yelin, who follows Schleier-Smith’s research. She gets results, even though “everything that exists in nature” is working against her experiments.

    Quantum physics describes a microworld where many possibilities reign. Unobserved atoms and particles don’t have clearly defined locations, and information can be shared by widely spaced parts of a system. “We have equations that describe quantum mechanics well, but we can’t solve them when we are dealing with more than a few particles,” Schleier-Smith says.

    That’s a shame, because understanding how large numbers of these small entities interact is essential to figuring out how our world works at the most fundamental level. Getting atoms to behave in just the right ways also has some practical benefits. It could lead to the most precise clocks yet, a boon for precision measurement, and to quantum computers that can solve problems that are too hard for today’s supercomputers.

    Schleier-Smith’s experimental setups use elaborate tabletop arrangements of mirrors, lasers, vacuum chambers and electronic parts to cool atoms, pin them in place and then manipulate them with light. It’s a clutter of essential components, the construction of which requires an exacting understanding of the physics at play plus engineering know-how.

    3
    Monika Schleier-Smith and her team trap cold atoms between two mirrors (shown). The setup allows the team to image the atoms.Schleier-Smith Lab

    As a graduate student at MIT, Schleier-Smith worked with a small team that pushed the precision of an atomic clock beyond what’s known as the “standard quantum limit,” a result reported in 2010 [Physical Review Letters]. Though people knew this was theoretically possible, many thought it was too hard to try to pull off. Schleier-Smith spent weeks optimizing and troubleshooting the control circuitry that kept the experiment’s lasers at the right frequency, says Ian Leroux, who was on the MIT team and is now at Canada’s National Research Council Metrology Research Centre in Ottawa. She has “that blend of care, dexterity, observation and attention to detail that lets her make an apparatus work better than it has any right to.”

    In a more recent experimental feat, reported in January in Physical Review Letters, Schleier-Smith and her Stanford team used laser light to create long-distance interactions in a cloud of some 100,000 cold rubidium atoms. The atoms chatted up other atoms half a millimeter away — a great distance for atoms. At Schleier-Smith’s direction, an excitation in the atoms, in this case a flip in a property called spin, hopped from one side of the atom cloud to another, using a photon to bypass the atoms in between. What’s more, the team found a way to image that hopping.

    5
    In a recent experiment, an excitation in trapped atoms, in this case a flip in a property called spin, was observed hopping across the atom cloud. The three cigar shapes show the hopping in a single cloud (spin states +1, -1 and 0, from top to bottom).Schleier-Smith Lab

    Schleier-Smith traces her interest in physics back to high school, when a chemistry teacher told her to think of an electron as “spread out like peanut butter.” The idea fascinated her. She sensed that a deeper understanding meant studying quantum mechanics.

    It’s not an insight you’d expect from the average high schooler. But such clarity of vision has been a characteristic of Schleier-Smith’s work.

    She quickly identifies ideas that are both interesting and experimentally feasible, says graduate student Emily Davis, who has worked in Schleier-Smith’s lab since 2013. (About half of the current lab members are female, atypical in such a male-dominated field.)

    “I tend to be fairly intuitive,” Schleier-Smith says. “I think it is a matter of how my brain works.”

    And she readily sees through other scientists’ questionable assumptions, Leroux says. With a cloud of thousands of atoms, her spin-hopping setup bucks a commonsense argument that you need to hold atoms in a very small space to get good control of their electromagnetic interactions.

    That setup might also have value in studying black holes. Theories that attempt to connect quantum physics with Albert Einstein’s theory of gravity — general relativity — lead to specific predictions about what happens to information that falls into black holes. The information might get mixed up exponentially quickly through long-range interactions analogous to those Schleier-Smith has demonstrated.

    “She has built an exceptionally powerful platform for exploring these phenomena in the lab,” says Stephen Shenker, a theoretical physicist at Stanford who works at the intersection of quantum physics and gravity.

    Could pursuing connections to black holes reveal something interesting about how atoms interact, as well as how to control those interactions? Schleier-Smith can’t say for sure, but she sees the potential.

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 11:38 am on October 3, 2019 Permalink | Reply
    Tags: "Brett McGuire searches space for the chemistry of life", , , , , , , , , Science News   

    From Science News: “Brett McGuire searches space for the chemistry of life” 

    From Science News

    October 2, 2019
    Lisa Grossman

    Cosmic molecules may point to the origins of carbon-based life.

    In a different reality, space might smell like almonds. After all, scientists surveying the chemicals in the cosmos have found benzonitrile; just a bit of the compound would fill your nostrils with a bitter almond scent.

    But our cosmos is too vast. “Space smells like nothing,” says astrochemist Brett McGuire. “There’s not enough to get an actual whiff.”

    2
    Astrochemist Brett McGuire combines skills in chemistry and astronomy to search for complex molecules in space. Courtesy of B. McGuire

    McGuire, 32, of the National Radio Astronomy Observatory in Charlottesville, Va., confirmed the presence of benzonitrile in a dark cloud in the Milky Way. He also discovered some of the other most complex molecules in space to date. By figuring out which molecules are out there, he and others hope to learn how the organic chemistry that undergirds all life on Earth — and perhaps anywhere else in the universe — gets started in space.

    McGuire got his start in space as an undergraduate chemistry major at the University of Illinois at Urbana-Champaign. During a talk, Ben McCall, now a sustainability expert at the University of Dayton in Ohio, explained what he does for a living. He said something like, “I blow shit up, torture it with lasers and then I look for it in space,” McGuire recalls.

    Enough said. McGuire spent that summer working in McCall’s lab, building a spectrometer to study how hydrogen gas, H2, reacts with H3+ — three hydrogen atoms with only two electrons. Some of McCall’s research included zapping gases of simple molecules with electricity — “an actual miniature lightning bolt,” McGuire says — to force atoms to recombine into new compounds that can’t be bought in a bottle.

    “Brett was a very precocious young scientist,” McCall says. “This was the only time I’ve had a student who really started a new instrument from scratch as an undergrad.”

    3
    The discovery of benzonitrile in a dust cloud in the Milky Way suggests that complex molecules can form from the buildup of smaller molecules in space. (Carbon is black, hydrogen white and nitrogen blue.) Ben Mills and Jynto/Wikimedia Commons

    Because space is so big and mostly empty, at least by Earth standards, it can take millions of years for two molecules flying around like billiard balls to get close enough to interact. “But it’s not just neutral billiard balls out there,” McGuire says. A charged molecule, like H3+, which has been discovered in interstellar space, can pull other molecules closer. “More or less all chemistry in space can trace itself back to H3+ at some point.”

    And all that chemistry includes some tantalizingly lifelike stuff. In 2016, McGuire and colleagues reported discovering propylene oxide in a gas cloud within the Milky Way.

    4
    MOLECULE CLUE A gas cloud (Sagittarius B2) near the center of the galaxy (Sagittarius A*) is loaded with propylene oxide, a molecule that comes in mirror-image configurations. B. Saxton, NRAO/AUI/NSF from data provided by N.E. Kassim, Naval Research Laboratory, Sloan Digital Sky Survey.

    That was the first molecule seen in space that, like the amino acids that make up proteins and are essential to life on Earth, has two forms that are mirror images of each other. Large rings of carbon and hydrogen, called polycyclic aromatic hydrocarbons, or PAHs, have also been spotted around dead or dying stars — though it’s been hard to tell how many carbons and hydrogens the PAHs contain.

    PAHs are thought to be the seeds of dust, planets and organic chemistry in our galaxy and other galaxies, McGuire says. So how do they form? “How do you go from H3+ to things that literally click together to make the building blocks of life?” he asks.

    The work of enumerating what’s out there mostly takes place in a lab on Earth. McGuire injects a puff of gas of the molecule he’s interested in into a large vacuum chamber, where the low temperature and pressure make the gas expand. Then he hits the gas with a pulse of intense microwave or radio radiation, sending the molecules tumbling. As they tumble, the molecules emit photons at a specific frequency. That light signature, called the molecule’s rotational spectrum, is what McGuire looks for when he searches for those molecules in space.

    Once McGuire knows the molecular fingerprint he’s after, he turns to radio telescopes to find the same print in space. Many scientists focus on one branch of this process or the other, the laboratory spectroscopy or the interstellar astronomy; only a few have expertise in both. “Brett is one of those very few people,” McCall says.

    To sniff almonds in space, McGuire and colleagues focused the Robert C. Byrd Green Bank Telescope in West Virginia on TMC-1, a dark cloud about 450 light-years from Earth “where maybe there are stars that are considering starting to form,” McGuire says. Forty hours of observing confirmed that benzonitrile, a benzene ring with a cyanide molecule stuck on the end, was there [Science].

    Green Bank Radio Telescope, West Virginia, USA, now the center piece of the GBO, Green Bank Observatory, being cut loose by the NSF

    6
    Scientists have detected complex molecules in TMC-1, a stellar nursery in the Milky Way. The cloud lacks big, bright stars, and its dust grains glow only faintly (shown in orange). ESO

    Lately, McGuire and colleagues are closing in on a bigger prize: specific PAHs in the space between stars. Knowing the makeup of PAHs in space will help reveal how they click together from smaller molecules, McGuire says. Finding these molecules would show that advanced chemistry is happening, in some cases before stars begin forming.

    Benzonitrile and the more complex molecules it hints at are “the first clear marker” of carbon-based chemistry in space, says Ryan Fortenberry, an astrochemist at the University of Mississippi in Oxford who wasn’t involved in the benzonitrile finding. “Before this, we were just kind of wandering around in the wilderness,” Fortenberry says. “Now we have found the trail.”

    See the full article here .


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    Please help promote STEM in your local schools.

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  • richardmitnick 9:24 am on September 17, 2019 Permalink | Reply
    Tags: , , , , , , , Ringing black holes, Science News   

    From Science News: “Gravitational waves from a ringing black hole support the no-hair theorem” 

    From Science News

    September 16, 2019
    Emily Conover

    General relativity suggests the spacetime oddities can be fully described by their mass and spin.

    1

    After two black holes collide and meld into one, the new black hole “rings” (illustrated), emitting gravitational waves before settling down into a quiet state. M. Isi/MIT, NASA

    For black holes, it’s tough to stand out from the crowd: Donning a mohawk is a no-no.

    Ripples in spacetime produced as two black holes merged into one suggest that the behemoths have no “hair,” scientists report in the Sept. 13 Physical Review Letters. That’s another way of saying that, as predicted by Einstein’s general theory of relativity, black holes have no distinguishing characteristics aside from mass and the rate at which they spin (SN: 9/24/10).

    “Black holes are very simple objects, in some sense,” says physicist Maximiliano Isi of MIT.

    Detected by the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, in 2015, the spacetime ripples resulted from a fateful encounter between two black holes, which spiraled around each other before crashing together to form one big black hole (SN: 2/11/16).

    MIT /Caltech Advanced aLigo

    In the aftermath of that coalescence, the newly formed big black hole went through a period of “ringdown.” It oscillated over several milliseconds as it emitted gravitational waves, similar to the way a struck bell vibrates and makes sound waves before eventually quieting down.

    Reverberating black holes emit gravitational waves not at a single frequency, but with additional, short-lived frequencies known as overtones — much like a bell rings with multiple tones in addition to its main pitch.

    Measuring the ringing black hole’s main frequency as well as one overtone allowed the researchers to compare those waves with the prediction for a hairless black hole. The results agreed within 20 percent.

    That result still leaves some wiggle room for the no-hair theorem to be proved wrong. But, “It’s a clear demonstration that the method works,” says physicist Leo Stein of the University of Mississippi in Oxford, who was not involved with the research. “And hopefully the precision will increase as LIGO improves.”

    The researchers also calculated the mass and spin of the black hole, using only waves from the ringdown period. The figures agreed with the values estimated from the entire event — including the spiraling and merging of the original two black holes — and so reinforced the idea that the resulting black hole’s behavior was determined entirely by its mass and spin.

    But just as a mostly bald man may sport a few strands, black holes could reveal some hair on closer inspection. If they do, that might lead to a solution to the information paradox, a puzzle about what happens to information that falls into a black hole (SN: 5/16/14). For example, in a 2016 attempt to resolve the paradox, physicist Stephen Hawking and colleagues suggested that black holes might have “soft hair” (SN: 4/3/18).

    “It could still be that these objects have more mysteries to them that will only be revealed by future, more sensitive measurements,” Isi 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

     
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