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  • richardmitnick 11:31 am on January 14, 2019 Permalink | Reply
    Tags: "NASA telescope spotted a black hole shrinking after it devoured a nearby star, , , , , , JAXA MAXI, NASA NICER   

    From Business Insider: “NASA telescope spotted a black hole shrinking after it devoured a nearby star” 

    From Business Insider

    Jan. 10, 2019
    Jackson Ryan

    1
    Artist’s impression of a black hole. NASA/JPL/Caltech.

    A black hole 10,000 light-years away from Earth was seen engulfing a nearby star into its center.
    NASA studied the X-rays (or light echoes) ricocheting off the black hole.
    Astronomers found that the corona in the black hole’s center shrunk signifcantly over time, which gave them an idea of how these objects may eventually evolve into supermassive black holes.
    You can watch a video of the black hole below.

    About 10,000 light years away from Earth, a black hole is engaged in a stellar feast, devouring the gases of a nearby star — and we’ve been watching.

    The stellar-mass black hole, around 10 times more massive than our sun, was discovered after a humongous X-ray flare in March 2018. It was originally detected by a specialized instrument aboard the International Space Station, operated by the Japanese Aerospace and Exploration Agency, known as the Monitor of All-sky X-ray Image (MAXI). After the X-ray burst captivated astronomers, researchers at MIT, the University of Maryland and NASA swung another instrument on board the station to watch what happened to the black hole, nicknamed J1820.

    JAXA MAXI

    It’s embarrassing when people watch you eat, but J1820 was none the wiser as NASA swung the Neutron star Interior Composition Explorer (NICER) to monitor its buffet.

    NASA/NICER on the ISS

    NICER continued to detect waves of X-ray light bouncing away from the black hole, called “light echoes”, which demonstrated how the black hole’s size and shape was changing over time.

    “NICER has allowed us to measure light echoes closer to a stellar-mass black hole than ever before,” said first author Erin Kara.

    The research, published on Jan. 10 in Nature, provides some tantalizing new evidence about the way a black hole evolves once it gobbles up a star. The major takeaway for the team was the the black hole’s corona was shrinking.

    Now, let’s back up — what does that actually mean? A black hole is a collapsed star with a core so dense that it has near-unimaginable gravitational power. Its gravity is so powerful that nothing — no particles, no light — can escape its pull. When a black hole begins to eat up a star, the star’s gases swirl around its gravitational center in a ring known as an accretion disk. Above that you have the corona: an extremely energetic region of subatomic particles.

    Because MAXI had caught the black hole’s initial outburst, the team began studying the X-rays emitted from the black hole over a month, measuring how they bounced off the accretion disk. By measuring the X-rays from the initial outburst and those received later on (the “light echoes”), the team could determine that the corona had shrunk from around 100 kilometers (around 62 miles) to just 10 (around 6 miles).

    2
    The largest known supermassive black hole is 13 billion light-years away.NASA Jet Propulsion Laboratory/Facebook

    “This is the first time that we’ve seen this kind of evidence that it’s the corona shrinking during this particular phase of outburst evolution,” said Jack Steiner, an astrophysicist with MIT.

    The team noted that generally, light echoes are only seen bouncing away from supermassive black holes, like the one at the center of the Milky Way, rather than this comparatively small stellar mass black hole. However, here, NICER — which was designed to examine faint, dense neutron stars — was crucial to precisely measuring them.

    But why the corona contracted in such a way remains a mystery. Steiner hypothesizes that as the gaseous accretion disk begins falling into the black hole, incredibly high pressures squeeze the corona’s particles and thus that leads to the cosmic shrinkage we see.

    Understanding the various parts of a black hole, such as the accretion disk or the corona, provide ways to study how black holes change over time. Although the study only looked at a stellar-mass black hole, at 10 times the mass of the sun, it may provide clues as to how black holes evolve to become “supermassive” and how that may influence the galaxies that swirl around them.

    See the full article here .

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  • richardmitnick 3:04 pm on January 9, 2019 Permalink | Reply
    Tags: , , , , , , NASA NICER, The findings are the first evidence that the corona shrinks as a black hole feeds or accretes   

    From MIT News: “Astronomers observe evolution of a black hole as it wolfs down stellar…” 

    MIT News
    MIT Widget

    From MIT News

    January 9, 2019
    Jennifer Chu

    1
    X-ray echoes, mapped by NASA’s Neutron star Interior Composition Explorer (NICER), revealed changes to the accretion disk and corona of black hole MAXI J1820+070.
    Image: NASA’s Goddard Space Flight Center

    NASA/NICER

    …Halo of highly energized electrons around the black hole contracts dramatically during feeding frenzy.

    On March 11, an instrument aboard the International Space Station detected an enormous explosion of X-ray light that grew to be six times as bright as the Crab Nebula, nearly 10,000 light years away from Earth. Scientists determined the source was a black hole caught in the midst of an outburst — an extreme phase in which a black hole can spew brilliant bursts of X-ray energy as it devours an avalanche of gas and dust from a nearby star.

    Now astronomers from MIT and elsewhere have detected “echoes” within this burst of X-ray emissions, that they believe could be a clue to how black holes evolve during an outburst. In a study published today in the journal Nature, the team reports evidence that as the black hole consumes enormous amounts of stellar material, its corona — the halo of highly-energized electrons that surrounds a black hole — significantly shrinks, from an initial expanse of about 100 kilometers (about the width of Massachusetts) to a mere 10 kilometers, in just over a month.

    The findings are the first evidence that the corona shrinks as a black hole feeds, or accretes. The results also suggest that it is the corona that drives a black hole’s evolution during the most extreme phase of its outburst.

    “This is the first time that we’ve seen this kind of evidence that it’s the corona shrinking during this particular phase of outburst evolution,” says Jack Steiner, a research scientist in MIT’s Kavli Institute for Astrophysics and Space Research. “The corona is still pretty mysterious, and we still have a loose understanding of what it is. But we now have evidence that the thing that’s evolving in the system is the structure of the corona itself.”

    Steiner’s MIT co-authors include Ronald Remillard and first author Erin Kara.

    X-ray echoes

    The black hole detected on March 11 was named MAXI J1820+070, for the instrument that detected it. The Monitor of All-sky X-ray Image (MAXI) mission is a set of X-ray detectors installed in the Japanese Experiment Module of the International Space Station (ISS), that monitors the entire sky for X-ray outbursts and flares.

    Soon after the instrument picked up the black hole’s outburst, Steiner and his colleagues started observing the event with NASA’s Neutron star Interior Composition Explorer, or NICER, another instrument aboard the ISS, which was designed partly by MIT, to measure the amount and timing of incoming X-ray photons.

    “This boomingly bright black hole came on the scene, and it was almost completely unobscured, so we got a very pristine view of what was going on,” Steiner says.

    A typical outburst can occur when a black hole sucks away enormous amounts of material from a nearby star. This material accumulates around the black hole, in a swirling vortex known as an accretion disk, which can span millions of miles across. Material in the disk that is closer to the center of the black hole spins faster, generating friction that heats up the disk.

    “The gas in the center is millions of degrees in temperature,” Steiner says. “When you heat something that hot, it shines out as X-rays. This disk can undergo avalanches and pour its gas down onto the central black hole at about a Mount Everest’s worth of gas per second. And that’s when it goes into outburst, which usually lasts about a year.”

    Scientists have previously observed that X-ray photons emitted by the accretion disk can ping-pong off high-energy electrons in a black hole’s corona. Steiner says some of these photons can scatter “out to infinity,” while others scatter back onto the accretion disk as higher-energy X-rays.

    By using NICER, the team was able to collect extremely precise measurements of both the energy and timing of X-ray photons throughout the black hole’s outburst. Crucially, they picked up “echoes,” or lags between low-energy photons (those that may have initially been emitted by the accretion disk) and high-energy photons (the X-rays that likely had interacted with the corona’s electrons). Over the course of a month, the researchers observed that the length of these lags decreased significantly, indicating that the distance between the corona and the accretion disk was also shrinking. But was it the disk or the corona that was shifting in?

    To answer this, the researchers measured a signature that astronomers know as the “iron line” — a feature that is emitted by the iron atoms in an accretion disk only when they are energized, such as by the reflection of X-ray photons off a corona’s electrons. Iron, therefore, can measure the inner boundary of an accretion disk.

    When the researchers measured the iron line throughout the outburst, they found no measurable change, suggesting that the disk itself was not shifting in shape, but remaining relatively stable. Together with the evidence of a diminishing X-ray lag, they concluded that it must be the corona that was changing, and shrinking as a result of the black hole’s outburst.

    “We see that the corona starts off as this bloated, 100-kilometer blob inside the inner accretion disk, then shrinks down to something like 10 kilometers, over about a month,” Steiner says. “This is the first unambiguous case of a corona shrinking while the disk is stable.”

    “NICER has allowed us to measure light echoes closer to a stellar-mass black hole than ever before,” Kara adds. “Previously these light echoes off the inner accretion disk were only seen in supermassive black holes, which are millions to billions of solar masses and evolve over millions of years. Stellar black holes like J1820 have much lower masses and evolve much faster, so we can see changes play out on human time scales.”

    While it’s unclear what is exactly causing the corona to contract, Steiner speculates that the cloud of high-energy electrons is being squeezed by the overwhelming pressure generated by the accretion disk’s in-falling avalanche of gas.

    The findings offer new insights into an important phase of a black hole’s outburst, known as a transition from a hard to a soft state. Scientists have known that at some point early on in an outburst, a black hole shifts from a “hard” phase that is dominated by the corona’s energy, to a “soft” phase that is ruled more by the accretion disk’s emissions.

    “This transition marks a fundamental change in a black hole’s mode of accretion,” Steiner says. “But we don’t know exactly what’s going on. How does a black hole transition from being dominated by a corona to its disk? Does the disk move in and take over, or does the corona change and dissipate in some way? This is something people have been trying to unravel for decades And now this is a definitive piece of work in regards to what’s happening in this transition phase, and that what’s changing is the corona.”

    This research is supported, in part, by NASA through the NICER mission and the Astrophysics Explorers Program.

    See the full article here .


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  • richardmitnick 11:57 am on July 18, 2017 Permalink | Reply
    Tags: , , , , NASA NICER, , NICER-Neutron star Interior Composition Explorer   

    From Goddard: “NASA Neutron Star Mission Begins Science Operations” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    7.17.17
    Clare Skelly
    NASA’s Goddard Space Flight Center, Greenbelt, Md.
    301-286-4994
    clare.a.skelly@nasa.gov

    1
    This time-lapse animation shows NICER being extracted from the SpaceX Dragon trunk on June 11, 2017. Credits: NASA.

    NASA’s new Neutron star Interior Composition Explorer (NICER) mission to study the densest observable objects in the universe has begun science operations.

    Launched June 3 on an 18-month baseline mission, NICER will help scientists understand the nature of the densest stable form of matter located deep in the cores of neutron stars using X-ray measurements.

    NICER operates around the clock on the International Space Station (ISS). In the two weeks following launch, NICER underwent extraction from the SpaceX Dragon spacecraft, robotic installation on ExPRESS Logistics Carrier 2 on board ISS and initial deployment. Commissioning efforts began June 14, as NICER deployed from its stowed launch configuration. All systems are functioning as expected.

    “No instrument like this has ever been built for the space station,” said Keith Gendreau, the principal investigator for NICER at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “As we transition from an instrument development project to a science investigation, it is important to recognize the fantastic engineering and instrument team who built a payload that delivers on all the promises made.”

    To date, NICER has observed over 40 celestial targets. These objects were used to calibrate the X-ray Timing Instrument and supporting star-tracker camera. The observations also validated the payload’s performance that will enable its key science measurements.


    Several cameras on the International Space Station have eyes on NICER. Since arriving to the space station on June 5 – aboard SpaceX’s eleventh cargo resupply mission – NICER underwent robotic installation on ExPRESS Logistics Carrier 2, initial deployment, precise point tests and more. This video shows segments of NICER’s time in space. Scientists and engineers will continue to watch NICER using these cameras throughout the mission’s science operations. Credits: NASA’s Goddard Space Flight Center.

    Along with the instrument’s transition to full science operations, the embedded Station Explorer for X-ray Timing and Navigation Technology (SEXTANT) demonstration will begin using NICER data to tune the built-in flight software for its first experiment.

    “Our initial timing models use data collected by terrestrial radio telescopes,” said Jason Mitchell, the SEXTANT project manager at Goddard. “Because NICER observes in X-rays, we will account for the difference between the pulses we recover in X-rays compared to our radio models.”

    2
    During NICER commissioning, an observation of low-mass X-ray binary 4U 1608–522 revealed a serendipitous Type I X-ray burst, a flare resulting from a thermonuclear explosion on the surface of a neutron star. 4U 1608 consists of a neutron star in a close orbit with a low-mass star from which it is drawing gas. As this matter accretes and piles up on the neutron star surface, its density in the strong-gravity environment increases until an explosive nuclear fusion reaction is ignited. The heated neutron star surface and atmosphere glow in X-rays, cooling and dimming over the span of about one minute. The hot-spot on the star swings in and out of NICER’s view as the star spins, approximately 619 times each second; these fluctuations in X-ray brightness, and their evolution during the burst, are indicated by the purple contours in the lower panel. NICER provides a unique such bursts, tracing flame propagation and other phenomena through the burst’s temperature and brightness changes over time, with simultaneous fast-timing and spectroscopy capability not previously available.
    Credits: NASA.

    Once NICER collects data on each of SEXTANT’s target pulsars, the software will exploit timing models developed using NICER-only data.

    NICER-SEXTANT is a two-in-one mission. NICER will study the strange, ultra-dense astrophysics objects known as neutron stars to determine how matter behaves in their interiors. SEXTANT will use NICER’s observations of rapidly rotating neutron stars, or pulsars, to demonstrate autonomous X-ray navigation in space.

    3
    GX 301–2, a high mass X-ray binary, is a system in which a massive, aging star’s dense wind is drawn toward the strong gravity of a neutron star. The column of falling material emits X-rays, dominated at certain times by the fluorescent glow of atoms of heavy metals such as iron and nickel. NICER’s X-ray detectors measure the energies (or colors) of X-ray photons – the technique of spectroscopy – to determine the chemical makeup and density of the accreting material in this 1,200-second exposure. Credits: NASA.

    NICER is an Astrophysics Mission of Opportunity within NASA’s Explorer program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA’s Space Technology Mission Directorate supports the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.

    For more information about NICER, visit:

    https://www.nasa.gov/nicer/

    To download NICER Multimedia:

    https://svs.gsfc.nasa.gov/Gallery/NICER.html

    For more information about SEXTANT, visit:

    https://gameon.nasa.gov/projects/deep-space-x-ray-navigation-and-communication/

    For more information about research and technology on the International Space Station, visit:

    https://www.nasa.gov/mission_pages/station/research/index.html

    See the full article here.

    Please help promote STEM in your local schools.

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    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


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  • richardmitnick 1:49 pm on June 13, 2017 Permalink | Reply
    Tags: , , , , Dr Wynn Ho, NASA NICER, ,   

    From Southampton: “Scientist works with NASA on world’s first neutron star mission” 

    U Southampton bloc

    University of Southampton

    9 June 2017
    No writer credit found

    A University of Southampton scientist will analyse data from the world’s first space mission devoted to the study of neutron stars – collapsed stars containing the densest matter in the Universe.

    1
    NICER is readied for its journey to the ISS. Credit: NASA

    NASA’s Neutron Star Interior Composition Explorer (NICER) mission arrived at the International Space Station this week, and will begin observing neutron stars after its installation as an external payload.

    The refrigerator-sized piece of equipment features 56 X-ray telescopes and silicon detectors to provide high-precision measurements of neutron stars.

    It will also test technology that relies on pulsars – spinning neutron stars that appear to wink on and off like lighthouses – as navigation beacons, a technique which could eventually be used to guide human exploration to the distant reaches of the solar system and beyond.

    Associate Professor Wynn Ho, of the University of Southampton, is an expert in neutron star interior composition, and part of a large team of scientists collaborating on the mission.

    1
    Dr Wynn Ho

    He will compute theoretical models that will be used to compare with the observational data obtained during the 18-month mission.

    He said: “I feel very privileged to be one of the few non-US-based scientists to have a major role in analyses of NICER’s science data. Neutron stars are unique tools for studying fundamental physics in environments that are inaccessible in laboratories on Earth.

    “With NICER, we hope to obtain valuable insights into nuclear and dense matter physics in a way that is complementary to results that will come out of gravitational wave detection of neutron stars, which our group here also works on.”

    Neutron stars are the remnants of massive stars that, after exhausting their nuclear fuel, went supernova and collapsed into super-dense spheres about 15 miles wide. Their intense gravity crushes an astonishing amount of matter — often more than 1.4 times the mass of the Sun, or at least 460,000 Earths — into these city-sized orbs, creating stable but incredibly dense matter not seen anywhere else in the universe. Just one teaspoonful of neutron star matter would weigh a billion tons on Earth.

    Although neutron stars emit radiation across the spectrum, observing them in the X-ray band offers unique insights into their structure and phenomena that can arise from these stars, including starquakes, thermonuclear explosions, and the most powerful magnetic fields in the Universe. NICER will collect X-rays generated from the stars’ tremendously strong magnetic fields and from hotspots located at their two magnetic poles.

    At these locations, the objects’ intense magnetic fields emerge from their interior and particles trapped within these fields rain down and generate X-rays when they strike the stars’ surfaces. In pulsars, these flowing particles emit powerful beams of radiation from the vicinity of the magnetic poles. On Earth these beams of radiation are observed as flashes of radiation ranging from milliseconds to seconds depending on how fast the pulsar rotates.

    Because these pulsations are predictable, they can be used as celestial clocks, providing high-precision timing, like the atomic-clock signals supplied through the Global Positioning System (GPS).

    Although ubiquitous on Earth, GPS signals weaken the farther one travels beyond Earth orbit. Pulsars, however, are accessible virtually everywhere in space, making them a valuable navigational solution for deep-space exploration.

    See the full article here .

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    The University of Southampton is a world-class university built on the quality and diversity of our community. Our staff place a high value on excellence and creativity, supporting independence of thought, and the freedom to challenge existing knowledge and beliefs through critical research and scholarship. Through our education and research we transform people’s lives and change the world for the better.

    Vision 2020 is the basis of our strategy.

    Since publication of the previous University Strategy in 2010 we have achieved much of what we set out to do against a backdrop of a major economic downturn and radical change in higher education in the UK.

    Vision 2020 builds on these foundations, describing our future ambition and priorities. It presents a vision of the University as a confident, growing, outwardly-focused institution that has global impact. It describes a connected institution equally committed to education and research, providing a distinctive educational experience for its students, and confident in its place as a leading international research university, achieving world-wide impact.

     
  • richardmitnick 1:27 pm on May 27, 2017 Permalink | Reply
    Tags: , , , , , NASA NICER, , New NASA Mission to Study Mysterious Neutron Stars and Aid in Deep Space Navigation   

    From Goddard: “New NASA Mission to Study Mysterious Neutron Stars, Aid in Deep Space Navigation” 

    NASA Goddard Banner
    NASA Goddard Space Flight Center

    May 26, 2017
    Claire Saravia
    claire.g.desaravia@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    A new NASA mission is headed for the International Space Station next month to observe one of the strangest observable objects in the universe.

    Launching June 1, the Neutron Star Interior Composition Explorer (NICER) will be installed aboard the space station as the first mission dedicated to studying neutron stars, a type of collapsed star that is so dense scientists are unsure how matter behaves deep inside it.

    NASA/NICER

    NASA NICER

    A neutron star begins its life as a star between about seven and 20 times the mass of our sun. When this type of star runs out of fuel, it collapses under its own weight, crushing its core and triggering a supernova explosion. What remains is an ultra-dense sphere only about 12 miles (20 kilometers) across, the size of a city, but with up to twice the mass of our sun squeezed inside. On Earth, one teaspoon of neutron star matter would weigh a billion tons.

    “If you took Mount Everest and squeezed it into something like a sugar cube, that’s the kind of density we’re talking about,” said Keith Gendreau, the principal investigator for NICER at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.


    Though we know neutron stars are small and extremely dense, there are still many aspects of these remnants of explosive deaths of other stars that we have yet to understand. NICER, a facility to be mounted on the outside of the International Space Station, seeks to find the answers to some of the questions still being asked about neutron stars. By capturing the arrival time and energy of the X-ray photons produced by pulsars emitted by neutron stars, NICER seeks to answer decades-old questions about extreme forms of matter and energy. Data from NICER will also be used in SEXTANT, an on-board demonstration of pulsar-based navigation. Credits: NASA’s Johnson Space Center

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    NASA’s Goddard Space Flight Center is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.


    NASA/Goddard Campus

     
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