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  • richardmitnick 11:31 am on August 18, 2018 Permalink | Reply
    Tags: A distant galaxy appears filled with dark matter, , , , , Bullet Cluster, , Science News   

    From Science News: “A galaxy 11.3 billion light-years away appears filled with dark matter” 

    From Science News

    August 17, 2018
    Lisa Grossman

    1
    LONG AGO AND FAR AWAY Using the telescopes of the Atacama Large Millimeter/submillimeter Array in Chile (shown), astronomers discovered the most distant yet galaxy that appears to be filled with dark matter.

    A distant galaxy appears filled with dark matter.

    The outermost stars in the Cosmic Seagull, a galaxy 11.3 billion light-years away, race too fast to be propelled by the gravity of the galaxy’s gas and stars alone. Instead, they move as if urged on by an invisible force, indicating the hidden presence of dark matter, astrophysicist Verónica Motta of the University of Valparaíso in Chile and her colleagues report August 8 [The Astrophysical Letters].

    “In our nearby universe, you see these halos of dark matter around galaxies like ours,” Motta says. “So we should expect that in the past, that halo was there, too.”

    Motta and her colleagues used radio telescopes at the Atacama Large Millimeter/submillimeter Array (ALMA) to measure the speed of gas across the Cosmic Seagull’s disk, from the center out to about 9,800 light-years. They found that the galaxy’s stars speed up as they get farther from the galaxy’s center.

    That’s a strange setup for most orbiting objects — when planets orbit a star, for instance, the most distant planets move slowest. But it can be explained if the galaxy’s far reaches are dominated by dark matter that speeds things along. Similar measurements of the Milky Way and neighboring galaxies provided one of the first signs that dark matter may exist, although physicists are still trying to detect the proposed particle directly (SN: 2/4/17, p. 15).

    Her team’s finding contrasts with a recent claim that such distant galaxies are oddly lacking in dark matter. That idea comes from a 2017 study by astronomer Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and his colleagues, who found more than 100 distant galaxies keep their slower stars at the edges and faster stars closer in — little to no dark matter required (SN: 4/15/17, p. 10).

    “In the astrophysical community, the [Genzel] result has been viewed with both excitement and skepticism,” says cosmologist Richard Ellis of University College London, who was not involved in either work. “It makes a lot of sense for others to examine galaxies at these [distances] in different ways.”

    Motta and her colleagues were able to probe dark matter in the most distant galaxy yet, thanks to a massive galactic train wreck called the Bullet Cluster that acted as a huge cosmic telescope.

    2
    M. Markevitch et al/CfA/CXC/NASA (X-ray); D. Clowe et al/U. Ariz./Magellan, ESO WFI, STScI/NASA (lensing map); D. Clowe et al/U. Ariz./Magellan, STScI/NASA (optical)

    The Cosmic Seagull lies behind the Bullet Cluster from Earth’s perspective, and the cluster’s mass distorts the Seagull’s light in a phenomenon called gravitational lensing.

    That distortion earned the disk-shaped galaxy its name — the first images reminded Motta’s team of the seagull logo of a popular music festival in Viña del Mar, Chile. But it also made the galaxy appear magnified by a factor of 50 — a new record.

    “Motta et al have exquisite data,” but their observations are limited, Ellis wrote in an e-mail. The team looked at only one galaxy, and that galaxy is much smaller and less massive than those that seem short on dark matter. Furthermore, the observations don’t cover the entire galactic disk, so the stars may be slower farther out than the team can see.

    Motta agrees that a distant slowdown is possible, although her observations cover the same portion of the galaxy’s disk as the study of galaxies that seem light on dark matter.

    “We are roughly at the place in which we should see the turning point” from fast to slow stars, if it exists, she says. “But we need to extend the study to get that.” Her team has been granted more time with ALMA next year to keep looking.

    See the full article here .


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  • richardmitnick 8:54 am on August 12, 2018 Permalink | Reply
    Tags: , , , , NASA Voyager 1 and 2, , New Horizons may have seen a glow at the solar system’s edge, Science News   

    From Science News: “New Horizons may have seen a glow at the solar system’s edge” 

    From Science News

    August 9, 2018
    Lisa Grossman

    The ultraviolet signal may mark a wall of hydrogen where the sun’s influence wanes.

    1
    HELLO FROM THE OTHER SIDE The sun’s journey through the galaxy may build a wall of hydrogen near the edge of the solar system (curved line to the left of this illustration). The New Horizons spacecraft may have seen evidence of just such a wall. Adler Planetarium/IBEX/NASA

    The New Horizons spacecraft has spotted an ultraviolet glow that seems to emanate from near the edge of the solar system.

    NASA New Horizons spacecraft

    That glow may come from a long-sought wall of hydrogen that represents where the sun’s influence wanes, the New Horizons team reports online August 7 in Geophysical Research Letters.

    “We’re seeing the threshold between being in the solar neighborhood and being in the galaxy,” says team member Leslie Young of the Southwest Research Institute, based in Boulder, Colo.

    Even before New Horizons flew past Pluto in 2015 (SN: 8/8/15, p. 6), the spacecraft was scanning the sky with its ultraviolet telescope to look for signs of the hydrogen wall. As the sun moves through the galaxy, it produces a constant stream of charged particles called the solar wind, which inflates a bubble around the solar system called the heliosphere. Just beyond the edge of that bubble, around 100 times farther from the sun than the Earth, uncharged hydrogen atoms in interstellar space should slow when they collide with solar wind particles. That build-up of hydrogen, or wall, should scatter ultraviolet light in a distinctive way.

    The two Voyager spacecraft saw signs of such light scattering 30 years ago.

    NASA/Voyager 1

    NASA/Voyager 2


    One of those craft has since exited the heliosphere and punched into interstellar space (SN: 10/19/13, p. 19).

    New Horizons is the first spacecraft in a position to double-check the Voyagers’ observations. It scanned the ultraviolet sky seven times from 2007 to 2017, space scientist Randy Gladstone of the Southwest Research Institute in San Antonio and colleagues report. As the spacecraft travelled, it saw the ultraviolet light change in a way that supports the decades-old observations. All three spacecraft saw more ultraviolet light farther from the sun than expected if there is no wall. But the team cautions that the light could also be from an unknown source farther away in the galaxy.

    “It’s really exciting if these data are able to distinguish the hydrogen wall,” says space scientist David McComas of Princeton University, who was not involved in the new work. That could help figure out the shape and variability of the solar system’s boundary (SN: 5/27/17, p. 15).

    After New Horizons flies past the outer solar system object Ultima Thule on New Year’s Day 2019 (SN Online: 3/14/18), the spacecraft will continue to look for the wall about twice each year until the mission’s end, hopefully 10 to 15 years from now, Gladstone says.

    If the ultraviolet light drops off at some point, then New Horizons may have left the wall in its rear view mirror. But if the light never fades, then its source could be farther ahead — coming from somewhere deeper in space, says team member Wayne Pryor of Central Arizona College in Coolidge.

    See the full article here .


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  • richardmitnick 9:58 am on June 21, 2018 Permalink | Reply
    Tags: , Science News, Underwater fiber-optic cables could moonlight as earthquake sensors   

    From Science News: “Underwater fiber-optic cables could moonlight as earthquake sensors” 


    From Science News

    June 14, 2018
    Maria Temming

    1
    MOTION OF THE OCEAN FLOOR The network of submarine fiber-optic cables that deliver work emails and cat videos to computers around the world could double as undersea earthquake detectors. Existing cables are shown in purple; planned cables are in blue.

    The global network of seafloor cables may be good for more than ferrying digital communication between continents. These fiber-optic cables could also serve as underwater earthquake detectors, researchers report online June 14 in Science.

    “It’s a very exciting proposition,” says Barbara Romanowicz, a seismologist at the University of California, Berkeley and the Collège de France in Paris.

    Almost all seismic stations around the world are based on land, leaving many oceanic earthquakes undetected. Harnessing the million-plus kilometers of underwater fiber-optic cables to monitor seafloor earthquakes would be “a great step forward” for studying Earth’s interior, Romanowicz says.

    What’s more, quake-detecting cables could bolster tsunami alert systems. “The more [seismic] stations feeding into a tsunami warning system, the faster it can give a warning,” says study coauthor Richard Luckett, a seismologist at the British Geological Survey in Edinburgh.

    To use a telecommunication cable as a seismic sensor, researchers inject light from a laser into one end of the optical fiber and monitor the light that exits the other end. When a seismic wave rattles the cable, it distorts the laser light travelling through it. By comparing the original laser signal with the light that exits the cable, researchers determine how much the beam was distorted along the way — and therefore the strength of the seismic wave that strummed the cable.

    Combining measurements from multiple fiber-optic cables can triangulate the earthquake’s point of origin, explains study coauthor Giuseppe Marra, a frequency metrology researcher at the National Physical Laboratory in Teddington, England. Once researchers know the strength of a seismic wave when it passed the cable and where the wave started, they can determine the original earthquake’s magnitude.

    ___________________________________________________________________
    Submarine seismology

    An underwater fiber-optic cable stretching from Malta to Sicily sensed a magnitude 3.4 quake in the Mediterranean Sea on September 2, 2017. Researchers confirmed this detection with two nearby seismometers. One seismometer near the Malta end of the cable, closer to the earthquake’s epicenter, detected the quake shortly before the cable, and a seismometer near the Sicily end identified it shortly after.

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    ___________________________________________________________________

    Marra and colleagues tested their quake-detecting technique on both land-based and submarine fiber-optic cables. One 79-kilometer cable in southern England sensed vibrations from quakes originating in New Zealand and Japan that seismometers put at magnitude 7.9 and 6.9, respectively. Other land-based cables in the United Kingdom and Italy sensed a magnitude 7.3 quake that rocked the Iraq-Iran border last November. And an underwater cable that runs 96 kilometers from Sicily to Malta detected a magnitude 3.4 tremor emanating from the middle of the Mediterranean Sea last September. This seismic sensing technique still needs to be tested on longer cables that cross oceans, Marra says.

    Fiber-optic cables that identify earthquakes far from land could provide new insight into geologic goings-on under the sea. For instance, better views of seafloor movements could help researchers understand how volcanism at mid-ocean ridges creates new oceanic crust, Luckett says (SN: 10/19/13, p. 22). Monitoring seafloor seismic activity could also help scientists study mantle plumes, upwellings of hot, buoyant rock within Earth’s mantle, Romanowicz says (SN: 10/22/11, p. 8).

    See the full article here .


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  • richardmitnick 10:14 am on June 20, 2018 Permalink | Reply
    Tags: , , , , Dark fusion?, , , Science News   

    From Science News: “If real, dark fusion could help demystify this physics puzzle” 


    From Science News

    June 6, 2018
    Emily Conover

    1
    DARK CLOUDS Galaxies and galaxy clusters are surrounded by dark matter (illustrated in blue over an image of the cluster Abell 2744; red indicates gas). Dark matter particles may undergo a process called dark fusion, one scientist suggests. XMM-Newton/ESA, WFI/ESO, NASA, CFHT

    Fusion may have a dark side. A shadowy hypothetical process called “dark fusion” could be occurring throughout the cosmos, a new study suggests.

    The standard type of fusion occurs when two atomic nuclei unite to form a new element, releasing energy in the process. “This is why the sun shines,” says physicist Sam McDermott of Fermilab in Batavia, Ill. A similar process — dark fusion — could occur with particles of dark matter, McDermott suggests in a paper published in the June 1, 2018 in Physical Review Letters.

    If the idea is correct, the proposed phenomenon may help physicists resolve a puzzle related to dark matter — a poorly understood substance believed to bulk up the mass of galaxies. Without dark matter, scientists can’t explain how galaxies’ stars move the way they do. But some of the quirks of how dark matter is distributed within galaxy centers remain a mystery.

    Dark matter is thought to be composed of reclusive particles that don’t interact much with ordinary matter — the stuff that makes up stars, planets and living creatures. That introverted nature is what makes the enigmatic particles so hard to detect. But dark matter may not be totally antisocial (SN: 3/3/18, p. 8). “Why wouldn’t the dark matter particles interact with each other? There’s really no good reason to say they wouldn’t,” says physicist Manoj Kaplinghat of the University of California, Irvine.

    Scientists have suggested that dark matter particles might ricochet off one another. But the new study goes a step further, proposing that pairs of dark matter particles could fuse, forming other unknown types of dark matter particles in the process.

    Such dark fusion could help explain why dark matter near the centers of galaxies is more evenly distributed than expected. In computer simulations of galaxy formation, the density of dark matter rises sharply toward a cusp in the center of a galaxy. But in reality, galaxies have a core evenly filled with dark matter.

    Those simulations assume dark matter particles don’t interact with one another. But dark fusion could change how the particles behave, giving them energy that would provide the oomph necessary to escape entrapment in a galaxy’s dense cusp, thereby producing an evenly filled core.

    “You can kick [particles] around through this interaction, so that’s kind of cool,” says physicist Annika Peter of the Ohio State University in Columbus. But, she says, dark fusion might end up kicking the particles out of the galaxy entirely, which wouldn’t mesh with expectations: The particles could escape the halo of dark matter that scientists believe surrounds each galaxy.

    For now, if fusion does have an alter ego, scientists remain in the dark.

    See the full article here .


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  • richardmitnick 2:14 pm on June 19, 2018 Permalink | Reply
    Tags: , , , , , Science News   

    From Science News: “Magnetic fields may be propping up the Pillars of Creation” 


    From Science News

    June 15, 2018
    Emily Conover

    The structure’s internal magnetism could mean the columns of gas and dust will be long-lived.

    1
    PILLAR OF STRENGTH Columns of cosmic gas and dust dubbed the Pillars of Creation (shown in this image from the Hubble Space Telescope) may be propped up by an internal magnetic field. NASA, ESA, Hubble Heritage Team/STScI and AURA

    The Pillars of Creation may keep standing tall due to the magnetic field within the star-forming region.

    For the first time, scientists have made a detailed map of the magnetic field inside the pillars, made famous by an iconic 1995 Hubble Space Telescope image (SN Online: 1/6/15). The data reveal that the field runs along the length of each pillar, perpendicular to the magnetic field outside. This configuration may be slowing the destruction of the columns of gas and dust, astronomer Kate Pattle and colleagues suggest in the June 10 Astrophysical Journal Letters.

    Hot ionized gas called plasma surrounds the pillars, located within the Eagle Nebula about 7,000 light-years from Earth. The pressure from that plasma could cause the pillars to pinch in at the middle like an hourglass before breaking up. However, the researchers suggest, the organization of the magnetic field within the pillars could be providing an outward force that resists the plasma’s onslaught, preventing the columns from disintegrating.

    The Pillars of Creation may keep standing tall due to the magnetic field within the star-forming region.

    For the first time, scientists have made a detailed map of the magnetic field inside the pillars, made famous by an iconic 1995 Hubble Space Telescope image (SN Online: 1/6/15). The data reveal that the field runs along the length of each pillar, perpendicular to the magnetic field outside. This configuration may be slowing the destruction of the columns of gas and dust, astronomer Kate Pattle and colleagues suggest in the June 10 Astrophysical Journal Letters.

    2
    FIELD OF DREAMS A map of the magnetic field within the Pillars of Creation reveals that the orientation of the field runs roughly parallel to each skinny column. White bars indicate the field’s orientation in that location. K. Pattle et al/Astrophysical Journal Letters 2018

    Hot ionized gas called plasma surrounds the pillars, located within the Eagle Nebula about 7,000 light-years from Earth. The pressure from that plasma could cause the pillars to pinch in at the middle like an hourglass before breaking up. However, the researchers suggest, the organization of the magnetic field within the pillars could be providing an outward force that resists the plasma’s onslaught, preventing the columns from disintegrating.

    Eagle Nebula NASA/ESA Hubble Public Domain

    The team studied light emitted from the pillars, measuring its polarization — the direction of the wiggling of the light’s electromagnetic waves — using the James Clerk Maxwell Telescope in Hawaii. Dust grains within the pillars are aligned with each other due to the magnetic field. These aligned particles emit polarized light, allowing the researchers to trace the direction of the magnetic field at various spots.

    “There are few clear measurements of the magnetic fields in objects like pillars,” says Koji Sugitani of Nagoya City University in Japan. To fully understand the formation of such objects, more observations are needed, he says.

    Studying objects where stars are born, such as the pillars, could help scientists better understand the role that magnetic fields may play in star formation (SN: 6/9/18, p. 12). “This is really one of the big unanswered questions,” says Pattle, of National Tsing Hua University in Hsinchu, Taiwan. “We just don’t have a very good idea of whether magnetic fields are important and, if they are, what they are doing.”

    See the full article here .


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  • richardmitnick 2:43 pm on May 10, 2018 Permalink | Reply
    Tags: , , , , , Gaia delivers a trove of data revealing secrets of the Milky Way, Science News   

    From Science News: “Gaia delivers a trove of data revealing secrets of the Milky Way” 


    From Science News

    May 9, 2018
    Emily Conover

    Astronomers are using the info to gauge the galaxy’s mass, size up exoplanets and more.

    1
    IN MOTION The Gaia spacecraft can reveal new features of the universe, thanks to its ability to track the movement of stars, like the rotation of the Large Magellanic Cloud, shown in this image based on light measured by Gaia.

    ESA/GAIA satellite

    The April 25 release of data from the European Space Agency’s Gaia spacecraft, which cataloged nearly 1.7 billion stars, has kicked off a scientific spree, with multiple papers published online in the last two weeks at arXiv.org.

    Charting stars in the Milky Way and beyond, Gaia surveys the entire sky. The spacecraft can measure stars’ motions and distances (SN Online: 4/25/18), properties which haven’t been inventoried on such a large scale before. “It’s really opening new dimensions in how we view stars,” says astronomer Ana Bonaca of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

    Because Gaia takes multiple images over time, “you’re not only getting a static picture of the sky at one instant, you’re looking at how it changes,” says astronomer Laura Watkins of the Space Telescope Science Institute in Baltimore. “We’ve never really had something like this before.”

    Here are five new observations made with the unprecedented info.

    1. Sizing up the Milky Way

    Pinning down the mass of our home galaxy is a hefty challenge. Much of the Milky Way’s mass is hidden in the form of a dark matter halo, a shroud of matter that is invisible except for its gravitational pull.

    Caterpillar Project A Milky-Way-size dark-matter halo and its subhalos circled, an enormous suite of simulations . Griffen et al. 2016

    But scientists can gauge the galaxy’s unseen bulk by observing objects moving at the outskirts of the galaxy.

    Combining information from Gaia and the Hubble Space Telescope, Watkins and colleagues estimated the galaxy’s mass using the motions of clumps of stars called globular clusters. The Milky Way is about 1.7 trillion times the mass of the sun, the team reports in a paper submitted April 30.

    2. Rescaling exoplanets

    Exoplanet updates are also on the agenda. Because NASA’s exoplanet-hunting Kepler telescope has limited ability in gauging how big stars are, the diameters of exoplanets passing in front of those stars were not well known (SN: 6/19/17).

    NASA/Kepler Telescope

    Planet transit. NASA/Ames

    “Gaia has now completely changed the game and solved this problem,” says astronomer Daniel Huber of the University of Hawaii at Manoa.

    Knowing both the brightness and distance of a star helps determine its size. So Huber and colleagues used Gaia’s data to better size up nearly 200,000 stars and more than 2,000 orbiting planets, the researchers report in a paper submitted May 1.

    3. Expanding a cosmic debate

    A disagreement over how fast the universe is expanding persists (SN Online: 1/16/18). Gaia data reinforced the discrepancy in results between two methods for measuring the expansion rate.

    One of those techniques involves estimating the distances of exploding stars, or supernovas, and measuring how their light is stretched by the expansion of space. Gaia improved distance estimates for variable stars called Cepheids, which scientists use to estimate how far away the supernovas are. The result: The expansion rate mismatch is now slightly worse, Adam Riess of the Space Telescope Science Institute and colleagues report in a paper submitted April 27.

    ___________________________________________________
    Cosmic centerpiece

    The Milky Way and its neighbors are revealed in this Gaia map of star density. Brighter regions are more densely populated, highlighting the plane of the galaxy, clumps of stars known as globular clusters, as well as neighboring dwarf galaxies including the Large Magellanic Cloud (larger spot in lower right).

    4
    ___________________________________________________

    4. Dipping into star streams

    The Milky Way is a violent beast, ripping up clumps of stars and stretching them into strands known as stellar streams. Bonaca and astronomer Adrian Price-Whelan of Princeton University study the longest thin stream in the Milky Way, known as GD-1, in a paper posted May 1.

    Gaia’s measurements of stars’ motions, combined with information about their brightness and color from the Hawaii-based Panoramic Survey Telescope and Rapid Response System, or Pan-STARRS, allowed the duo to pinpoint which stars were going with the flow of the stellar stream.

    Pannstars telescope, U Hawaii, Mauna Kea, Hawaii, USA, Altitude 3,052 m (10,013 ft)

    The data also revealed gaps where stars seem to be missing. That could indicate the stream was disturbed in the past by a close encounter with a clump of dark matter.

    5. Spotting speed demons

    Several teams used Gaia to pick out fast-moving stars, zipping through the galaxy at speeds of more than 1,000 kilometers per second. A team including Ken Shen of the University of California, Berkeley seized on this capability to look for clues to the origins of a kind of explosion called a type 1a supernova, thought to occur when a dead star known as a white dwarf explodes.

    Scientists don’t know exactly what causes a white dwarf explosion. In one theory, two white dwarfs swirl around one another as one steals material from the other. The thief eventually explodes and its partner is flung away at high speed.

    Shen and colleagues wasted no time in hunting for these fast-moving white dwarfs. Within an hour and a half of the Gaia data release, the team had the first of several ground-based telescopes taking a closer look at some of the speed demons. Three stars potentially fit the bill for coming from a type 1a supernova, the team reports in a paper submitted April 30.

    This is only the beginning of the Gaiapalooza, though. The data is so rich, Watkins says, “it’s going to take us months and years to get to grips with what’s there.”

    See the full article here .

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  • richardmitnick 2:27 pm on December 25, 2017 Permalink | Reply
    Tags: Astronomers Find Galaxy Cluster with Mass of Two Quadrillion Suns, , , , , , , Science News   

    From Science News: “Astronomers Find Galaxy Cluster with Mass of Two Quadrillion Suns” 

    SciNews

    Dec 25, 2017

    NASA and ESO astronomers have joined forces to observe RCS2 J2327-0204, one of the most massive galaxy clusters known at its distance or beyond.

    1
    The galaxy cluster RCS2 J2327-0204. Image credit: ESO / NASA / ESA / Hubble.

    RCS2 J2327-0204 is an extremely massive cluster of galaxies located approximately 6 billion light-years away.

    Massive objects such as RCS2 J2327-0204 have such a strong influence on their surroundings that they visibly warp the space around them. This effect is known as gravitational lensing.

    Gravitational Lensing NASA/ESA

    In this way, they cause the light from more distant objects to be bent, distorted, and magnified, allowing us to see galaxies that would otherwise be far too distant to detect.

    Gravitational lensing is one of the predictions of Albert Einstein’s theory of general relativity.

    Strong lensing produces stunning images of distorted galaxies and sweeping arcs; both of which can be seen in this image.

    Weak gravitational lensing, on the other hand, is more subtle, hardly seen directly in an image, and is mostly studied statistically — but it provides a way to measure the masses of cosmic objects, as in the case of this cluster.

    This image of RCS2 J2327-0204 is a composite of observations from the HAWK-I instrument on ESO’s Very Large Telescope and the Advanced Camera for Surveys (ACS) instrument on the NASA/ESA Hubble Space Telescope.

    ESO HAWK-I on the ESO VLT


    ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    NASA/ESA Hubble ACS

    NASA/ESA Hubble Telescope

    It demonstrates an impressively detailed collaborative approach to studying weak lensing in the cosmos.

    The astronomers found RCS2 J2327-0204 to contain the mass of two quadrillion Suns.

    The diffuse blue and white image covering the picture shows a mass map. It is connected to the amount of mass thought to be contained within each region.

    See the full article here .

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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” 

    ScienceNews bloc

    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” 

    ScienceNews bloc

    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” 

    ScienceNews bloc

    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.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
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