Tagged: NASA SWIFT Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 10:00 pm on December 7, 2022 Permalink | Reply
    Tags: "NASA Missions Probe Game-Changing Cosmic Explosion", , , , , , , , , NASA SWIFT, Scientists sometimes observe short bursts with a following flare of visible and infrared light called a kilonova., The burst named GRB 211211A was paradigm-shifting as it is the first long-duration gamma-ray burst traced to a neutron star merger origin., The decay from the neutron star merger results in the production of heavy elements like gold and platinum., This discovery has deep implications for how the universe’s heavy elements came to be.   

    From The NASA Goddard Space Flight Center: “NASA Missions Probe Game-Changing Cosmic Explosion” 

    NASA Goddard Banner

    From The NASA Goddard Space Flight Center

    12.7.22
    By Jeanette Kazmierczak
    jeanette.a.kazmierczak@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md

    Media Contact:
    Claire Andreoli
    claire.andreoli@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md

    4
    Gamma-ray burst 211211A, the location of which is circled in red, erupted on the outskirts of a spiral galaxy around 1 billion light-years away in the constellation Boötes. The NASA/ESA Hubble Space Telescope captured the image with its Wide Field Camera 3 and Advanced Camera for Surveys. Credit: NASA, ESA, Rastinejad et al. (2022), and Gladys Kober (Catholic Univ. of America)

    On Dec. 11, 2021, NASA’s Neil Gehrels Swift Observatory and Fermi Gamma-ray Space Telescope detected a blast of high-energy light from the outskirts of a galaxy around 1 billion light-years away. The event has rattled scientists’ understanding of gamma-ray bursts (GRBs), the most powerful events in the universe.


    For the last few decades, astronomers have generally divided GRBs into two categories. Long bursts emit gamma rays for two seconds or more and originate from the formation of dense objects like black holes in the centers of massive collapsing stars. Short bursts emit gamma rays for less than two seconds and are caused by mergers of dense objects like neutron stars. Scientists sometimes observe short bursts with a following flare of visible and infrared light called a kilonova.

    “This burst, named GRB 211211A, was paradigm-shifting as it is the first long-duration gamma-ray burst traced to a neutron star merger origin,” said Jillian Rastinejad, a graduate student at Northwestern University in Evanston, Illinois, who led one team that studied the burst.

    “The high-energy burst lasted about a minute, and our follow-up observations led to the identification of a kilonova. This discovery has deep implications for how the universe’s heavy elements came to be.”


    NASA’s Fermi, Swift Capture Revolutionary Gamma-Ray Burst.
    Watch to learn how an event called GRB 211211A rocked scientists’s understanding of gamma-ray bursts – the most powerful explosions in the cosmos. Credit: NASA’s Goddard Space Flight Center.

    A classic short gamma-ray burst begins with two orbiting neutron stars, the crushed remnants of massive stars that exploded as supernovae. As the stars circle ever closer, they strip neutron-rich material from each other. They also generate gravitational waves, or ripples in space-time – although none were detected from this event.

    Eventually the neutron stars collide and merge, creating a cloud of hot debris emitting light across multiple wavelengths. Scientists hypothesize that jets of high-speed particles, launched by the merger, produce the initial gamma-ray flare before they collide with the wreckage. Heat generated by the radioactive decay of elements in the neutron-rich debris likely creates the kilonova’s visible and infrared light. This decay results in the production of heavy elements like gold and platinum.

    “Many years ago, Neil Gehrels, an astrophysicist and Swift’s namesake, suggested that neutron star mergers could produce some long bursts,” said Eleonora Troja, an astrophysicist at the University of Rome who led another team that studied the burst. “The kilonova we observed is the proof that connects mergers to these long-duration events, forcing us to rethink how black holes are formed.”

    Fermi and Swift detected the burst simultaneously, and Swift was able to rapidly identify its location in the constellation Boötes, enabling other facilities to quickly respond with follow-up observations. Their observations have provided the earliest look yet at the first stages of a kilonova.

    Many research groups have delved into the observations collected by Swift, Fermi, the Hubble Space Telescope, and others.

    Some have suggested the burst’s oddities could be explained by the merger of a neutron star with another massive object, like a black hole. The event was also relatively nearby, by gamma-ray burst standards, which may have allowed telescopes to catch the kilonova’s fainter light. Perhaps some distant long bursts could also produce kilonovae, but we haven’t been able to see them.

    3
    Two neutron stars begin to merge in this illustration, blasting a jet of high-speed particles and producing a cloud of debris. Scientists think these kinds of events are factories for a significant portion of the universe’s heavy elements, including gold. Credits: A. Simonnet (Sonoma State Univ.) and NASA’s Goddard Space Flight Center.

    The light following the burst, called the afterglow emission, also exhibited unusual features. Fermi detected high-energy gamma rays starting 1.5 hours post-burst and lasting more than 2 hours. These gamma rays reached energies of up to 1 billion electron volts. (Visible light’s energy measures between about 2 and 3 electron volts, for comparison.)

    “This is the first time we’ve seen such an excess of high-energy gamma rays in the afterglow of a merger event. Normally that emission decreases over time,” said Alessio Mei, a doctoral candidate at the Gran Sasso Science Institute in L’Aquila, Italy, who led a group that studied the data. “It’s possible these high-energy gamma rays come from collisions between visible light from the kilonova and electrons in particle jets. The jets could be weakening ones from the original explosion or new ones powered by the resulting black hole or magnetar.”

    Scientists think neutron star mergers are a major source of the universe’s heavy elements. They based their estimates on the rate of short bursts thought to occur across the cosmos. Now they’ll need to factor long bursts into their calculations as well.

    A team led by Benjamin Gompertz, an astrophysicist at the University of Birmingham in the United Kingdom, looked at the entire high-energy light curve, or the evolution of the event’s brightness over time. The scientists noted features that might provide a key for identifying similar incidents – long bursts from mergers – in the future, even ones that are dimmer or more distant. The more astronomers can find, the more they can refine their understanding of this new class of phenomena.

    On Dec. 7, 2022, papers led by Rastinejad, Troja, and Mei were published in the scientific journal Nature [below], and a paper led by Gompertz was published in Nature Astronomy [below].

    “This result underscores the importance of our missions working together and with others to provide multiwavelength follow up of these kinds of phenomenon,” said Regina Caputo, Swift project scientist, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Similar coordinated efforts have hinted that some supernovae might produce short bursts, but this event is the final nail in the coffin for the simple dichotomy we’ve used for years. You never know when you might find something surprising.”

    NASA’s Goddard Space Flight Center manages the Swift and Fermi missions.

    Swift is a collaboration with The Pennsylvania State University, the DOE’s Los Alamos National Laboratory in New Mexico, and Northrop Grumman Space Systems in Dulles, Virginia, with important contributions from partners in the United Kingdom and Italy.

    Fermi is a collaboration with the U.S. Department of Energy, with important contributions from partners in France, Germany, Italy, Japan, Sweden, and the United States.

    The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). Goddard manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

    Science papers:
    Nature
    https://www.nature.com/articles/s41586-022-05390-w
    Nature
    https://www.nature.com/articles/s41586-022-05327-3
    Nature
    https://www.nature.com/articles/s41586-022-05404-7
    Nature Astronomy
    https://www.nature.com/articles/s41550-022-01819-4

    See the full article here.

    Comments are invited and will be appreciated, especially if the reader finds any errors which I can correct. Use “Reply”.


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

    Please help promote STEM in your local schools.


    Stem Education Coalition


    NASA/Goddard Campus

    NASA’s Goddard Space Flight Center, Greenbelt, MD 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.

    GSFC also operates two spaceflight tracking and data acquisition networks (the NASA Deep Space Network and the Near Earth Network); develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration.

    GSFC manages operations for many NASA and international missions including the NASA/ESA Hubble Space Telescope; the Explorers Program; the Discovery Program; the Earth Observing System; INTEGRAL; MAVEN; OSIRIS-REx; the Solar and Heliospheric Observatory ; the Solar Dynamics Observatory; Tracking and Data Relay Satellite System ; Fermi; and Swift. Past missions managed by GSFC include the Rossi X-ray Timing Explorer (RXTE), Compton Gamma Ray Observatory, SMM, COBE, IUE, and ROSAT. Typically, unmanned Earth observation missions and observatories in Earth orbit are managed by GSFC, while unmanned planetary missions are managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California.

    Goddard is one of four centers built by NASA since its founding on July 29, 1958. It is NASA’s first, and oldest, space center. Its original charter was to perform five major functions on behalf of NASA: technology development and fabrication; planning; scientific research; technical operations; and project management. The center is organized into several directorates, each charged with one of these key functions.

    Until May 1, 1959, NASA’s presence in Greenbelt, MD was known as the Beltsville Space Center. It was then renamed the Goddard Space Flight Center (GSFC), after Robert H. Goddard. Its first 157 employees transferred from the United States Navy’s Project Vanguard missile program, but continued their work at the Naval Research Laboratory in Washington, D.C., while the center was under construction.

    Goddard Space Flight Center contributed to Project Mercury, America’s first manned space flight program. The Center assumed a lead role for the project in its early days and managed the first 250 employees involved in the effort, who were stationed at Langley Research Center in Hampton, Virginia. However, the size and scope of Project Mercury soon prompted NASA to build a new Manned Spacecraft Center, now the Johnson Space Center, in Houston, Texas. Project Mercury’s personnel and activities were transferred there in 1961.

    The Goddard network tracked many early manned and unmanned spacecraft.

    Goddard Space Flight Center remained involved in the manned space flight program, providing computer support and radar tracking of flights through a worldwide network of ground stations called the Spacecraft Tracking and Data Acquisition Network (STDN). However, the Center focused primarily on designing unmanned satellites and spacecraft for scientific research missions. Goddard pioneered several fields of spacecraft development, including modular spacecraft design, which reduced costs and made it possible to repair satellites in orbit. Goddard’s Solar Max satellite, launched in 1980, was repaired by astronauts on the Space Shuttle Challenger in 1984. The Hubble Space Telescope, launched in 1990, remains in service and continues to grow in capability thanks to its modular design and multiple servicing missions by the Space Shuttle.

    Today, the center remains involved in each of NASA’s key programs. Goddard has developed more instruments for planetary exploration than any other organization, among them scientific instruments sent to every planet in the Solar System. The center’s contribution to the Earth Science Enterprise includes several spacecraft in the Earth Observing System fleet as well as EOSDIS, a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during extra-vehicular activity, and operates the Lunar Reconnaissance Orbiter, a spacecraft designed to study the Moon in preparation for future manned exploration.

    The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

    President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

    Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

    NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [Hubble, Chandra, Spitzer, and associated programs.] NASA shares data with various national and international organizations such as from the [JAXA]Greenhouse Gases Observing Satellite.

     
  • richardmitnick 6:04 pm on September 11, 2017 Permalink | Reply
    Tags: , , , , , Modeling the Radiation of Black Holes, NASA SWIFT,   

    From CfA: “Modeling the Radiation of Black Holes” 

    Harvard Smithsonian Center for Astrophysics


    Center For Astrophysics

    August 25, 2017

    1
    An X-ray image of two ultraluminous X-ray sources (ULXs) in the Andromeda galaxy. New calculations confirm that ULXs are usually stellar-mass black holes rapidly accreting material and emitting radiation in a narrow beam. NASA/Swift/Stefan Immler

    NASA/SWIFT Telescope

    Ultraluminous X-ray sources (ULXs) are extremely luminous, compact X-ray sources found in some nearby spiral galaxies. The nature of these mysterious sources is not well understood, but they are thought to be black holes of about ten solar-masses accreting material, and are distinct both in size and character from the supermassive black holes in the nuclei of galaxies that also emit bright X-rays. The class of ULXs appears to contain several physical variants: one subsample shows coherent pulsations and is thought to be composed of neutron stars rather than black holes, while another set might be more massive than a star. Even a single type might change its emission character with time between the several morphological classes identified.

    Astronomers trying to model ULXs face several challenges. The strong gravitational field means that the calculations must be done in a full general relativity context, and moreover the observations indicate that the emission is not spherical but instead is typically highly beamed. Not least, powerful magnetic fields are expected to be present and must in included in the simulations. CfA astronomer Ramesh Narayan and two colleagues used their new computer codes to calculate the emission properties and spatial appearances of ULXs, taking into account the complexities of relativity, magnetic fields, beaming, and varying accretion rates. Their results are in good agreement with previous, less sophisticated calculations. They conclude that observed large luminosities are in part caused by focusing of the emission by the geometry of the system. This raises the question, to be pursued in further research, of whether the observed population of ULXs is only the tip of the iceberg with many more ULXs oriented away from our line-of-sight, and if so, where this large population comes from.
    Reference(s):

    Spectra of Black Hole Accretion Models of Ultra-Luminous X-ray Sources,” Ramesh Narayan, Aleksander Sadowski, Roberto Soria, MNRAS 2017 (in press).

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.

     
  • richardmitnick 8:42 am on March 22, 2017 Permalink | Reply
    Tags: , , , , , NASA SWIFT, Star’s death spiral into black hole   

    From EarthSky: “Star’s death spiral into black hole” 

    1

    EarthSky

    March 22, 2017
    Eleanor Imster

    NASA said on March 20, 2017 that scientists used data from its Swift satellite to get a comprehensive look at a star’s death spiral into a black hole.


    NASA/SWIFT Telescope

    The star was much like our sun. The black hole contains some 3 million times the mass of our sun and lies at the center of a galaxy 290 million light-years away. As the black hole tore the star apart, it produced what scientists call a tidal disruption event. They’ve labeled this particular event – an eruption of optical, ultraviolet, and X-ray light, which began reaching Earth in 2014 – as ASASSN-14li.

    2
    Astronomers report the detection of flows of hot, ionized gas in high-resolution X-ray spectra of a nearby tidal disruption event, ASASSN-14li in the galaxy PGC 43234. This artist’s impression shows a supermassive black hole at the center of PGC 43234 accreting mass from a star that dared to venture too close to the galaxy’s center. Image credit: ESA / C. Carreau.

    The scientists have now used Swift’s data to map out how and where these different wavelengths were produced, as the shattered star’s debris circled the black hole. The video animation above is an artist’s depiction of what these scientists believe happened. They said it took awhile for debris from the star to be swallowed up by the black hole.

    Dheeraj Pasham, an astrophysicist at the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts, and the lead researcher of the study, said:

    “We discovered brightness changes in X-rays that occurred about a month after similar changes were observed in visible and UV light. We think this means the optical and UV emission arose far from the black hole, where elliptical streams of orbiting matter crashed into each other.”

    Their study was published March 15, 2017 in the Astrophysical Journal Letters.

    A tidal disruption event happens when a star passes too close to a very massive black hole. ASASSN-14li is the closest tidal disruption discovered in 10 years, so of course astronomers are studying it as extensively as they can. During events like this, tidal forces from a black hole may convert the star into a stream of debris. Stellar debris falling toward the black hole doesn’t fall straight in, however, but instead collects into a spinning accretion disk, encircling the hole.

    The accretion disk is the source of all the action, as observed by earthly astronomers.

    Within the disk, star material becomes compressed and heated before eventually spilling over the black hole’s event horizon, the point beyond which nothing can escape and astronomers cannot observe.

    The animation above, from NASA’s Goddard Space Flight Center illustrates:

    … how debris from a tidally disrupted star collides with itself, creating shock waves that emit ultraviolet and optical light far from the black hole. According to Swift observations of ASASSN-14li, these clumps took about a month to fall back to the black hole, where they produced changes in the X-ray emission that correlated with the earlier UV and optical changes.

    According to the scientists, the ASASSN-14li black hole’s event horizon is typically about 13 times bigger in volume than our sun. Meanwhile, the accretion disk formed by the disrupted star might extend to more than twice Earth’s distance from the sun.

    Bottom line: A team of scientists used observations from NASA’s Swift satellite have mapped the death spiral of a star as it was destroyed by the black hole at the center of its galaxy.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 9:12 am on October 31, 2016 Permalink | Reply
    Tags: , , , NASA Missions Harvest a Passel of ‘Pumpkin’ Stars, NASA SWIFT   

    From Goddard: “NASA Missions Harvest a Passel of ‘Pumpkin’ Stars” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    Oct. 27, 2016
    Francis Reddy
    francis.j.reddy@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    Astronomers using observations from NASA’s Kepler and Swift missions have discovered a batch of rapidly spinning stars that produce X-rays at more than 100 times the peak levels ever seen from the sun. The stars, which spin so fast they’ve been squashed into pumpkin-like shapes, are thought to be the result of close binary systems where two sun-like stars merge.

    NASA/Kepler Telescope
    NASA/Kepler Telescope

    NASA/SWIFT Telescope
    NASA/SWIFT Telescope


    Access mp4 video here .
    Dive into the Kepler field and learn more about the origins of these rapidly spinning stars.
    Credits: Credits: NASA’s Goddard Space Flight Center/Scott Wiessinger, producer

    “These 18 stars rotate in just a few days on average, while the sun takes nearly a month,” said Steve Howell, a senior research scientist at NASA’s Ames Research Center in Moffett Field, California, and leader of the team. “The rapid rotation amplifies the same kind of activity we see on the sun, such as sunspots and solar flares, and essentially sends it into overdrive.”

    The most extreme member of the group, a K-type orange giant dubbed KSw 71, is more than 10 times larger than the sun, rotates in just 5.5 days, and produces X-ray emission 4,000 times greater than the sun does at solar maximum.

    2
    This artist’s concept illustrates how the most extreme “pumpkin star” found by Kepler and Swift compares with the sun. Both stars are shown to scale. KSw 71 is larger, cooler and redder than the sun and rotates four times faster. Rapid spin causes the star to flatten into a pumpkin shape, which results in brighter poles and a darker equator. Rapid rotation also drives increased levels of stellar activity such as starspots, flares and prominences, producing X-ray emission over 4,000 times more intense than the peak emission from the sun. KSw 71 is thought to have recently formed following the merger of two sun-like stars in a close binary system. Credits: NASA’s Goddard Space Flight Center/Francis Reddy

    These rare stars were found as part of an X-ray survey of the original Kepler field of view, a patch of the sky comprising parts of the constellations Cygnus and Lyra. From May 2009 to May 2013, Kepler measured the brightness of more than 150,000 stars in this region to detect the regular dimming from planets passing in front of their host stars. The mission was immensely successful, netting more than 2,300 confirmed exoplanets and nearly 5,000 candidates to date. An ongoing extended mission, called K2, continues this work in areas of the sky located along the ecliptic, the plane of Earth’s orbit around the sun.

    “A side benefit of the Kepler mission is that its initial field of view is now one of the best-studied parts of the sky,” said team member Padi Boyd, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who designed the Swift survey. For example, the entire area was observed in infrared light by NASA’s Wide-field Infrared Survey Explorer, and NASA’s Galaxy Evolution Explorer observed many parts of it in the ultraviolet.

    NASA/Galex telescope
    NASA/Galex telescope

    “Our group was looking for variable X-ray sources with optical counterparts seen by Kepler, especially active galaxies, where a central black hole drives the emissions,” she explained.

    Using the X-ray and ultraviolet/optical telescopes aboard Swift, the researchers conducted the Kepler–Swift Active Galaxies and Stars Survey (KSwAGS), imaging about six square degrees, or 12 times the apparent size of a full moon, in the Kepler field.

    “With KSwAGS we found 93 new X-ray sources, about evenly split between active galaxies and various types of X-ray stars,” said team member Krista Lynne Smith, a graduate student at the University of Maryland, College Park who led the analysis of Swift data. “Many of these sources have never been observed before in X-rays or ultraviolet light.”

    For the brightest sources, the team obtained spectra using the 200-inch telescope at Palomar Observatory in California.

    Caltech Palomar 200 inch Hale Telescope, at Mt Wilson, CA, USA
    Caltech Palomar 200 inch Hale Telescope interior
    Caltech Palomar 200 inch Hale Telescope, at Mt Wilson, CA, USA

    These spectra provide detailed chemical portraits of the stars and show clear evidence of enhanced stellar activity, particularly strong diagnostic lines of calcium and hydrogen.

    The researchers used Kepler measurements to determine the rotation periods and sizes for 10 of the stars, which range from 2.9 to 10.5 times larger than the sun. Their surface temperatures range from somewhat hotter to slightly cooler than the sun, mostly spanning spectral types F through K. Astronomers classify the stars as subgiants and giants, which are more advanced evolutionary phases than the sun’s caused by greater depletion of their primary fuel source, hydrogen. All of them eventually will become much larger red giant stars.

    A paper detailing the findings will be published in the Nov. 1 edition of the Astrophysical Journal and is now available online.

    Forty years ago, Ronald Webbink at the University of Illinois, Urbana-Champaign noted that close binary systems cannot survive once the fuel supply of one star dwindles and it starts to enlarge. The stars coalesce to form a single rapidly spinning star initially residing in a so-called “excretion” disk formed by gas thrown out during the merger. The disk dissipates over the next 100 million years, leaving behind a very active, rapidly spinning star.

    Howell and his colleagues suggest that their 18 KSwAGS stars formed by this scenario and have only recently dissipated their disks. To identify so many stars passing through such a cosmically brief phase of development is a real boon to stellar astronomers.

    “Webbink’s model suggests we should find about 160 of these stars in the entire Kepler field,” said co-author Elena Mason, a researcher at the Italian National Institute for Astrophysics Astronomical Observatory of Trieste. “What we have found is in line with theoretical expectations when we account for the small portion of the field we observed with Swift.”

    The team has already extended their Swift observations to additional fields mapped by the K2 mission.

    Ames manages the Kepler and K2 missions for NASA’s Science Mission Directorate. NASA’s Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

    Goddard manages the Swift mission in collaboration with Pennsylvania State University in University Park, the Los Alamos National Laboratory in New Mexico and Orbital Sciences Corp. in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

    Related Links

    NASA’s Kepler and K2 mission website
    NASA’s Swift mission website

    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
    NASA/Goddard Campus
    NASA image

     
  • richardmitnick 2:14 pm on September 28, 2016 Permalink | Reply
    Tags: , , , NASA SWIFT, Scientists investigate unidentified radio sources   

    From phys.org: “Scientists investigate unidentified radio sources” 

    physdotorg
    phys.org

    September 28, 2016
    Tomasz Nowakowski

    1
    The sky map in the direction of the radio source designated 3C 86, obtained by XRT in the 0.3–10 keV energy band (left panel) and by WISE in the w1 filter (right panel). A yellow dashed line marks the positional uncertainty region of the 3CR source. White continuous lines shape the radio contours obtained from the NVSS map and corresponding to 0.01, 0.2, 0.7, 2, and 4 Jy beam−1; a white cross marks the position of the catalogued NVSS source. A red circle marks the position of the detected XRT source with the corresponding error radius. Credit: Maselli et al., 2016.

    A team of researchers led by Andrea Maselli of the Institute of Space Astrophysics and Cosmic Physics of Palermo, Italy, has conducted an observational campaign of a group of unassociated radio sources with NASA’s Swift space observatory.

    NASA/SWIFT Telescope
    NASA/SWIFT Telescope

    The observations were aimed at revealing the true nature of these so far unidentified sources. The results were published Sept. 23 in a paper on arXiv.org.

    The Swift spacecraft, scanning the universe in the gamma-ray, X-ray, ultraviolet, and optical wavebands, is an invaluable tool when it comes to studying gamma-ray bursts and other electromagnetic events. It has already proved its scientific importance in many ways, for example by performing the first sensitive hard X-ray survey of the sky.

    Recently, Maselli and his team employed Swift to observe 21 bright radio sources included in the revised Third Cambridge Catalogue (3CR) of radio sources. The catalog contains celestial radio sources detected at 178 MHz that could advance our knowledge about the nature and evolution of powerful radio galaxies and quasars.

    However, some sources described in the 3CR catalog, including these detected by the NRAO VLA Sky Survey (NVSS), are not only unobserved in X-rays, but are, in fact, completely unidentified, lacking an assigned optical or infrared counterpart.

    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA
    NRAO/VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA

    The authors of the paper decided to fill this gap by conducting a supplementary optical-to-X-ray campaign with the Swift spacecraft, in order to better characterize the properties of these unidentified sources.

    “We have investigated a group of unassociated radio sources included in the 3CR catalog to increase the multi-frequency information on them and possibly obtain an identification,” the researchers wrote in the paper.

    Each of the 21 sources was observed by two telescopes onboard Swift – the X-ray Telescope (XRT) and the Ultraviolet/Optical Telescope (UVOT). The observation campaign lasted from November 2014 to March 2015.

    According to the research, out of these 21 investigated sources, nine exhibit significant emission in the soft X-ray band. The scientists managed to assign an infrared counterpart in the AllWISE (All Wide-field Infrared Survey Explorer) catalog for these nine sources and in four cases with no soft X-ray association.

    “After conducting Swift observations of 21 bright NVSS sources corresponding to 3CR sources classified as unassociated in the third update of the 3CR catalogue, we have obtained new X-ray detections for nine of them. Moreover, cross-matching the NVSS with the recent AllWISE Catalogue, we have found a WISE counterpart to all these nine X-ray sources, as well as to four cases with no X-ray detection,” the paper reads.

    What baffled the researchers is that no optical/UV counterpart has been found by UVOT, what lead them to an assumption that these unidentified radio sources should be classified as obscured active galaxies. However, the team added that it is too early to draw final conclusions as spectroscopic observations are needed to confirm this hypothesis.

    “Our analysis suggests that a spectroscopic analysis in the infrared range will be more helpful to identify their nature as well as potentially obtain a redshift measurement,” the team wrote.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 7:46 am on June 24, 2016 Permalink | Reply
    Tags: , , , NASA SWIFT   

    From Goddard: “X-ray Echoes of a Shredded Star Provide Close-up of ‘Killer’ Black Hole” 

    NASA Goddard Banner

    NASA Goddard Space Flight Center

    June 22, 2016
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland
    francis.j.reddy@nasa.gov

    Some 3.9 billion years ago in the heart of a distant galaxy, the intense tidal pull of a monster black hole shredded a star that passed too close. When X-rays produced in this event first reached Earth on March 28, 2011, they were detected by NASA’s Swift satellite, which notified astronomers around the world.

    NASA/SWIFT Telescope
    NASA/SWIFT Telescope

    Within days, scientists concluded that the outburst, now known as Swift J1644+57, represented both the tidal disruption of a star and the sudden flare-up of a previously inactive black hole.


    Access mp4 video here .
    NASA Goddard astronomer Erin Kara discusses the discovery of X-ray echoes from Swift J1644+57, a black hole that shattered a passing star. X-rays produced by flares near this million-solar-mass black hole bounced off the nascent accretion disk and revealed its structure. Credits: NASA’s Goddard Space Flight Center

    Now astronomers using archival observations from Swift, the European Space Agency’s (ESA) XMM-Newton observatory and the Japan-led Suzaku satellite have identified the reflections of X-ray flares erupting during the event.

    ESA/XMM Newton
    ESA/XMM Newton

    JAXA/Suzaku satellite
    JAXA/Suzaku satellite

    Led by Erin Kara, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, College Park (UMCP), the team has used these light echoes, or reverberations, to map the flow of gas near a newly awakened black hole for the first time.

    “While we don’t yet understand what causes X-ray flares near the black hole, we know that when one occurs we can detect its echo a couple of minutes later, once the light has reached and illuminated parts of the flow,” Kara explained. “This technique, called X-ray reverberation mapping, has been previously used to explore stable disks around black holes, but this is the first time we’ve applied it to a newly formed disk produced by a tidal disruption.”


    Access mp4 video here .
    Astronomers using data from the European Space Agency’s XMM-Newton satellite have found a long-sought X-ray signal from NGC 4151, a galaxy that contains a supermassive black hole. When the black hole’s X-ray source flares, its accretion disk brightens about half an hour later. The discovery promises a new way to unravel what’s happening in the neighborhood of these powerful objects. Credit: NASA’s Goddard Space Flight Center

    1
    In this artist’s rendering, a thick accretion disk has formed around a supermassive black hole following the tidal disruption of a star that wandered too close. Stellar debris has fallen toward the black hole and collected into a thick chaotic disk of hot gas. Flashes of X-ray light near the center of the disk result in light echoes that allow astronomers to map the structure of the funnel-like flow, revealing for the first time strong gravity effects around a normally quiescent black hole. Credits: NASA/Swift/Aurore Simonnet, Sonoma State University

    Stellar debris falling toward a black hole collects into a rotating structure called an accretion disk. There the gas is compressed and heated to millions of degrees before it eventually spills over the black hole’s event horizon, the point beyond which nothing can escape and astronomers cannot observe. The Swift J1644+57 accretion disk was thicker, more turbulent and more chaotic than stable disks, which have had time to settle down into an orderly routine. The researchers present the findings in a paper published online in the journal Nature on Wed., June 22.

    One surprise from the study is that high-energy X-rays arise from the inner part of the disk. Astronomers had thought most of this emission originated from a narrow jet of particles accelerated to near the speed of light. In blazars, the most luminous galaxy class powered by supermassive black holes, jets produce most of the highest-energy emission.

    “We do see a jet from Swift J1644, but the X-rays are coming from a compact region near the black hole at the base of a steep funnel of inflowing gas we’re looking down into,” said co-author Lixin Dai, a postdoctoral researcher at UMCP. “The gas producing the echoes is itself flowing outward along the surface of the funnel at speeds up to half the speed of light.”

    X-rays originating near the black hole excite iron ions in the whirling gas, causing them to fluoresce with a distinctive high-energy glow called iron K-line emission. As an X-ray flare brightens and fades, the gas follows in turn after a brief delay depending on its distance from the source.

    “Direct light from the flare has different properties than its echo, and we can detect reverberations by monitoring how the brightness changes across different X-ray energies,” said co-author Jon Miller, a professor of astronomy at the University of Michigan in Ann Arbor.

    Swift J1644+57 is one of only three tidal disruptions that have produced high-energy X-rays, and to date it remains the only event caught at the peak of this emission. These star shredding episodes briefly activate black holes astronomers wouldn’t otherwise know about. For every black hole now actively accreting gas and producing light, astronomers think nine others are dormant and dark. These quiescent black holes were active when the universe was younger, and they played an important role in how galaxies evolved. Tidal disruptions therefore offer a glimpse of the silent majority of supersized black holes.

    3
    Images from Swift’s Ultraviolet/Optical (white, purple) and X-Ray telescopes (yellow and red) were combined in this composite of Swift J1644+57, an X-ray outburst astronomers classify as a tidal disruption event. The event is seen only in the X-ray image, which is a 3.4-hour exposure taken on March 28, 2011. The outburst was triggered when a passing star came too close to a supermassive black hole. The star was torn apart, and much of the gas fell toward the black hole. To date, this is the only tidal disruption event emitting high-energy X-rays that astronomers have caught at peak luminosity. Credits: NASA/Swift/Stefan Immler

    “If we only look at active black holes, we might be getting a strongly biased sample,” said team member Chris Reynolds, a professor of astronomy at UMCP. “It could be that these black holes all fit within some narrow range of spins and masses. So it’s important to study the entire population to make sure we’re not biased.”

    The researchers estimate the mass of the Swift J1644+57 black hole at about a million times that of the sun but did not measure its spin. With future improvements in understanding and modeling accretion flows, the team thinks it may be possible to do so.

    ESA’s XMM-Newton satellite was launched in December 1999 from Kourou, French Guiana. NASA funded elements of the XMM-Newton instrument package and provides the NASA Guest Observer Facility at Goddard, which supports use of the observatory by U.S. astronomers. Suzaku operated from July 2005 to August 2015 and was developed at the Japanese Institute of Space and Astronautical Science, which is part of the Japan Aerospace Exploration Agency, in collaboration with NASA and other Japanese and U.S. institutions.

    NASA’s Swift satellite was launched in November 2004 and is managed by Goddard. It is operated in collaboration with Penn State University in University Park, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corp. in Dulles, Virginia, with international collaborators in the U.K., Italy, Germany and Japan.

    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
    NASA/Goddard Campus
    NASA

     
  • richardmitnick 8:18 am on November 8, 2015 Permalink | Reply
    Tags: , , NASA SWIFT   

    From NASA Swift: “NASA’s Swift Spots its Thousandth Gamma-ray Burst” 

    NASA Swift Banner

    NASA SWIFT Telescope

    NASA Swift

    Nov. 6, 2015
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    1
    GRB 151027B, Swift’s 1,000th burst (center), is shown in this composite X-ray, ultraviolet and optical image. X-rays were captured by Swift’s X-Ray Telescope, which began observing the field 3.4 minutes after the Burst Alert Telescope detected the blast. Swift’s Ultraviolet/Optical Telescope (UVOT) began observations seven seconds later and faintly detected the burst in visible light. The image includes X-rays with energies from 300 to 6,000 electron volts, primarily from the burst, and lower-energy light seen through the UVOT’s visible, blue and ultraviolet filters (shown, respectively, in red, green and blue). The image has a cumulative exposure of 10.4 hours. Credits: NASA/Swift/Phil Evans, Univ. of Leicester

    NASA’s Swift spacecraft has detected its 1,000th gamma-ray burst (GRB). GRBs are the most powerful explosions in the universe, typically associated with the collapse of a massive star and the birth of a black hole.

    “Detecting GRBs is Swift’s bread and butter, and we’re now at 1,000 and counting,” said Neil Gehrels, the Swift principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The spacecraft remains in great shape after nearly 11 years in space, and we expect to see many more GRBs to come.”

    A GRB is a fleeting blast of high-energy light, often lasting a minute or less, occurring somewhere in the sky every couple of days. Scientists are looking for exceptional bursts that offer the deepest insights into the extreme physical processes at work.

    2
    This illustration shows the ingredients of the most common type of gamma-ray burst. The core of a massive star (left) has collapsed, forming a black hole that sends a jet moving through the collapsing star and out into space at near the speed of light. Radiation across the spectrum arises from hot ionized gas in the vicinity of the newborn black hole, collisions among shells of fast-moving gas within the jet, and from the leading edge of the jet as it sweeps up and interacts with its surroundings. Credits: NASA’s Goddard Space Flight Center

    Shortly before 6:41 p.m. EDT on Oct. 27, Swift’s Burst Alert Telescope detected the 1,000th GRB as a sudden pulse of gamma rays arising from a location toward the constellation Eridanus. Astronomers dubbed the event GRB 151027B, after the detection date and the fact that it was the second burst of the day. Swift automatically determined its location, broadcast the position to astronomers around the world, and turned to investigate the source with its own sensitive X-ray, ultraviolet and optical telescopes.

    Astronomers classify GRBs by their duration. Like GRB 151027B, roughly 90 percent of bursts are of the “long” variety, where the gamma-ray pulse lasts more than two seconds. They are believed to occur in a massive star whose core has run out of fuel and collapsed into a black hole. As matter falls toward the newly formed black hole, it launches jets of subatomic particles that move out through the star’s outer layers at nearly the speed of light. When the particle jets reach the stellar surface, they emit gamma rays, the most energetic form of light. In many cases, the star is later seen to explode as a supernova.

    “Short” bursts last less than two seconds — and sometimes just thousandths of a second. Swift observations provide strong evidence these events are caused by mergers of orbiting neutron stars or black holes.

    Once a GRB is identified, the race is on to observe its fading light with as many instruments as possible. Based on alerts from Swift, robotic observatories and human-operated telescopes turn to the blast site to measure its rapidly fading afterglow, which emits X-rays, ultraviolet, visible and infrared light, and radio waves. While optical afterglows are generally faint, they can briefly become bright enough to be seen with the unaided eye.

    “Over the years, astronomers have constantly refined their techniques to get their telescopes onto the burst site in the shortest possible time,” said John Nousek, Swift’s director of mission operations and a professor of astronomy and astrophysics at Penn State University in University Park, Pennsylvania. “In fact, the process to follow up Swift GRB alerts is as productive as ever.”

    GRB 151027B provides a perfect example. Five hours after the Swift alert, the burst location first became visible from the European Southern Observatory (ESO) in Paranal, Chile. There a team led by Dong Xu of the Chinese National Astronomical Observatories in Beijing captured the afterglow’s visible light using the Very Large Telescope’s X-shooter spectrograph. The ESO observations show that light from the burst had been traveling to us for more than 12 billion years, placing it in the most distant few percent of GRBs Swift has recorded.

    ESO VLT Interferometer
    ESO/VLT

    ESO X-shooter
    Very Large Telescope’s X-shooter spectrograph

    Astronomers now have distance measurements for about 30 percent of Swift GRBs, which makes it possible to investigate how these powerful events are distributed across space and time. The distance record is held by GRB 090429B, which exploded at the dawn of star formation in the universe. Its light took more than 13 billion years to reach Earth.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on November 20, 2004, at 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international consortium from the United States, United Kingdom, and Italy. It is part of NASA’s Medium Explorer Program (MIDEX).

     
  • richardmitnick 5:45 pm on December 9, 2014 Permalink | Reply
    Tags: , , , , , NASA SWIFT   

    From blueshift: “Happy Birthday, Swift!” 

    NASA Blueshift
    NASA Blueshift

    December 9, 2014
    Maggie Masetti

    This is our third Happy Birthday post for a satellite in the last year or so – which is pretty cool actually, to have satellites that are hitting significant milestones and have had the longevity to still be doing great science. We had Fermi’s 5th birthday in August 2013, followed by Spitzer’s 10th in September 2013.

    NASA Fermi Telescope
    NASA/Fermi

    NASA Spitzer Telescope
    NASA/Spitzer

    And then we just recently hit Swift’s 10th birthday. What is Swift? Swift is an observatory that has been dedicated to studying gamma-ray bursts (GRBs) – and it can study GRBs and their afterglows at gamma ray, X-ray, ultraviolet, and optical wavelengths.

    NASA SWIFT Telescope
    NASA/Swift

    GRBs are short-lived bursts of gamma-ray light, which can last from few milliseconds to several minutes, and shine hundreds of times brighter than a typical supernova and about a million trillion times as bright as our Sun. Furthermore, when a GRB erupts, it is briefly the brightest source of cosmic gamma ray photons in the observable Universe. (Thanks to Imagine the Universe!, more info there.) What exactly was causing these incredibly energetic bursts was a big mystery. Enter Swift. Data from Swift (and also the gamma-ray Fermi observatory) have given us valuable clues that are helping us solve this mystery. (We got the scoop on the latest in the interview you’ll see below.

    We actually built Swift here at NASA Goddard. I was fortunate enough to get the chance to see the satellite before it launched. They displayed it in its cleanroom. Here is me 10 years ago with Brendan, Steve, and Meredith. (Meredith and Steve have been a huge help to Blueshift behind the scenes on the server side of things.)
    m

    s
    With Swift

    Sara and I talked to the Principal Investigator for the Swift mission, Neil Gehrels, to ask him 10 questions about Swift for its 10th Anniversary.

    Blueshift: What is your role with Swift? How long have you been involved with the project?

    Neil Gehrels: I am the lead scientist of Swift. In NASA jargon, my role is Principal Investigator. My involvement started at the very beginning in 1996 when Nick White and I conceived of the mission.

    Blueshift: How did Swift come to be?

    Neil Gehrels: NASA has competitions every other year for small to medium sized missions. Typically 40 teams put in proposals and one is chosen to fly through a rigorous and grueling peer review process. We proposed Swift in 1998 and were fortunate enough to have it selected. The observatory was constructed from 1999 to 2004 and then launched.

    Blueshift: Were you at the launch? What was it like to watch Swift head into space?

    Neil Gehrels: Yes, I was in the control center at the launch. It was one of the most exciting days of my life. Exhilaration mixed with fear of failure! Luckily everything went perfectly.

    Blueshift: Why gamma rays? What are they, and what do they tell us about the Universe?

    Neil Gehrels: Gamma rays are like really powerful X-rays. Just like the X-rays at the dentist office, they are very penetrating rays of light. The are produced in the hottest, most explosive events in the universe. We use them to study the death of stars and birth of black holes.

    Blueshift: What’s Swift’s role within the international fleet of astrophysics satellites?

    Neil Gehrels: Swift is the NASA’s premier satellite for observing the most explosive and dynamic sources in the universe. Objects such as gamma-ray bursts and supernovae. The observatory detects the transient sources and then repoints itself, without human intervention, at the source for detailed observations with the on-board telescopes

    Blueshift: What research have you personally done with Swift?

    Neil Gehrels: My personal research is studying gamma-ray bursts. Whenever one is detected by Swift, which occurs about twice per week, I receive a text message on my phone and run to the nearest computer to look at the new data.

    Blueshift: Did you expect to still be doing amazing science with Swift ten years later?

    Neil Gehrels: Swift was built to operate for 2 years, but hoped it would go much longer. It is such a joy to have it still working perfectly after ten years.

    Blueshift: Has Swift helped provide answers to major astronomical mysteries such as the cause of gamma-ray bursts?

    Neil Gehrels: Yes, Swift has made major discoveries every year. We found out that long and short gamma-ray bursts have very different origins. Long bursts are from exploding stars and short bursts are from the collision of compact neutron stars. Another big finding was the detection of 2 gamma-ray bursts from the very distant edges of the universe. They were produced in the explosions of very early stars.

    Blueshift: What do you think are the top discoveries made by Swift over the last decade?

    Neil Gehrels: In addition to the major discoveries about gamma-ray bursts, another biggie was detecting a the shredding of a star by a massive black hole. The star drifted too close to the black hole and was torn apart by the strong gravity of the black hole. Another fun discovery was a flash of X-rays from a new supernova explosion. We were lucky to be looking in the direction of a new supernova at the time the star first collapsed and discovered a brilliant pulse of X-rays. It was the long-predict “shock break-out” where a wave of heat zooms through the star at the moment of collapse and bursts out of the surface.

    Blueshift: What’s next for Swift?

    Neil Gehrels: Hopefully Swift will last another 10 years. We are using it in a new way lately, as a resource for astronomers. Our colleagues send an alert to us when they find something interesting going on in the universe and we point Swift at it.

    Blueshift:Thanks!

    And happy birthday to Swift, we hope you have many more!

    c
    The cake from Swift’s birthday party. Credit: Maggie Masetti

    See the full article, with animation, here.

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    Blueshift is produced by a team of contributors in the Astrophysics Science Division at Goddard. Started in 2007, Blueshift came from our desire to make the fascinating stuff going on here every day accessible to the outside world.

    NASANASA Goddard Banner

     
  • richardmitnick 8:18 pm on November 20, 2014 Permalink | Reply
    Tags: , , , , NASA SWIFT   

    From NASA/Swift: “10 Years of Game-changing Astrophysics” 

    NASA Swift Banner

    NASA SWIFT Telescope

    NASA Swift

    November 20, 2014
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    Over the past decade, NASA’s Swift Gamma-ray Burst Explorer has proven itself to be one of the most versatile astrophysics missions ever flown. It remains the only satellite capable of precisely locating gamma-ray bursts — the universe’s most powerful explosions — and monitoring them across a broad range of wavelengths using multiple instruments before they fade from view.

    “Swift” isn’t just a name — it’s a core capability, a part of the spacecraft’s DNA. Gamma-ray bursts (GRBs) typically last less than a minute and Swift detects one event about twice a week. Once Swift observes a GRB, it automatically determines the blast’s location, broadcasts the position to the astronomical community, and then turns toward the site to investigate with its own sensitive telescopes.

    “This process can take as little as 40 seconds, which is so quick we sometimes catch the tail end of the GRB itself,” said John Nousek, the director of mission operations and a professor of astrophysics at Penn State University in University Park, Pennsylvania. “Because Swift autonomously responds to sudden bursts of high-energy light, it also provides us with data on a wide range of short-lived events, such as X-ray flares from stars and other objects.”

    NASA’s Swift satellite rode to orbit aboard a Delta II rocket on November 20, 2004, and it’s still going strong. Swift’s unique instrumentation allows it to quickly locate an interesting high-energy outburst, automatically determine its position, and rapidly investigate it with ultraviolet, optical, and X-ray telescopes. Swift’s versatility has led to amazing observations across a wide swath of astronomy. As Swift begins its second decade of operation, its speed, flexibility and versatility make it an important platform for studying the most energetic and rapidly changing phenomena in the cosmos.


    From colliding asteroids to a star shredded by a monster black hole, this video showcases highlights from NASA Swift’s decade of discovery.
    Image Credit: NASA’s Goddard Space Flight Center

    To date, Swift has detected more than 900 GRBs. Its discoveries include a new ultra-long class, whose high-energy emissions endure for hours; the farthest GRB, whose light took more than 13 billion years to reach us; and the “naked-eye” GRB, which for about a minute was bright enough to see with the naked-eye despite the fact that its light had traveled 7.5 billion years. Early in the mission, Swift observations provided the “smoking gun” that validated long-standing theoretical models suggesting that GRBs with durations under two seconds come from mergers of two neutron stars, objects with the mass of the sun that have been crushed to the size of a city.

    In addition to its studies of GRBs, Swift conducts a wide array of observations of other astrophysical phenomena. A flexible planning system enables astronomers to request Swift “target-of-opportunity” (TOO) observations, which can be commanded from the ground in as little as 10 minutes, or set up monitoring programs to observe specific sources at time intervals ranging from minutes to months. The system can schedule up to 75 independent targets a day.

    “These characteristics make Swift a pioneer in a burgeoning field we call ‘time-domain’ astronomy,” said Neil Gehrels, the mission’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Just as we extended telescopic astronomy from visible light to other wavelengths, we are now beginning to study how the properties of astronomical objects change across a wide range of timescales, from less than a second to decades.”

    grb
    In the most common type of gamma-ray burst, illustrated here, a dying massive star forms a black hole (left), which drives a particle jet into space. Light across the spectrum arises from hot gas near the black hole, collisions within the jet, and through the jet’s interaction with its surroundings. Image Credit: NASA’s Goddard Space Flight Center

    Some projects require years of observations, such as long-term monitoring of the center of our galaxy — and its dormant supermassive black hole — with Swift’s X-Ray Telescope (XRT). Astronomers also are using the spacecraft’s Burst Alert Telescope to conduct a continuing survey of more than 700 active galaxies, where monster black holes devour large amounts of gas and shine brightly in X-rays and gamma rays.

    Shorter-term projects included observations to map the nearest galaxies in the ultraviolet. The most demanding object was the Large Magellanic Cloud, a small satellite galaxy orbiting our own at a distance of about 163,000 light-years. Swift’s Ultraviolet/Optical Telescope (UVOT) captured 2,200 overlapping “snapshots” to cover the galaxy, producing the best-ever view in the UV. “The UVOT is the only telescope that can produce high-resolution wide-field multicolor surveys in the ultraviolet,” said Michael Siegel, who leads the UVOT instrument team at Penn State.

    lmc
    Large Magellanic Cloud


    Swift scientists discuss the mission, the science, and recall their personal experiences as members of the team.
    Image Credit: NASA’s Goddard Space Flight Center

    Over the past decade, NASA’s Swift Gamma-ray Burst Explorer has proven itself to be one of the most versatile astrophysics missions ever flown. It remains the only satellite capable of precisely locating gamma-ray bursts — the universe’s most powerful explosions — and monitoring them across a broad range of wavelengths using multiple instruments before they fade from view.

    “Swift” isn’t just a name — it’s a core capability, a part of the spacecraft’s DNA. Gamma-ray bursts (GRBs) typically last less than a minute and Swift detects one event about twice a week. Once Swift observes a GRB, it automatically determines the blast’s location, broadcasts the position to the astronomical community, and then turns toward the site to investigate with its own sensitive telescopes.

    In 10 years of operation, Swift has made 315,000 individual observations of 26,000 separate targets, supporting nearly 6,200 TOO requests by more than 1,500 scientists. Its observations range from optical and ultraviolet studies of comets and asteroids to catching X-rays and gamma-rays from some of the most distant objects in the universe.

    Another major highlight of Swift’s studies of some 300 supernovae was the 2008 discovery of X-ray signals produced by a star caught in the act of exploding. Shockwaves breaching the surface of the dying star produced this brilliant flash.

    Swift rocketed into orbit on Nov. 20, 2004. Managed by NASA Goddard, the mission is operated in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and Orbital Sciences Corporation in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory and the Italian Space Agency in Italy, with additional collaborators in Germany and Japan.

    Earlier this year, Swift ranked highly in NASA’s 2014 Senior Review of Operating Missions and will continue its enormously productive scientific work through at least 2016.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on November 20, 2004, at 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international consortium from the United States, United Kingdom, and Italy. It is part of NASA’s Medium Explorer Program (MIDEX).


    ScienceSprings is powered by MAINGEAR computers

     
  • richardmitnick 4:55 pm on September 30, 2014 Permalink | Reply
    Tags: , , , , NASA SWIFT   

    From NASA/SWIFT: “NASA’s Swift Mission Observes Mega Flares from a Mini Star” 

    NASA Swift Banner

    NASA SWIFT Telescope

    NASA Swift

    September 30, 2014
    Francis Reddy
    NASA’s Goddard Space Flight Center, Greenbelt, Maryland

    On April 23, NASA’s Swift satellite detected the strongest, hottest, and longest-lasting sequence of stellar flares ever seen from a nearby red dwarf star. The initial blast from this record-setting series of explosions was as much as 10,000 times more powerful than the largest solar flare ever recorded.

    “We used to think major flaring episodes from red dwarfs lasted no more than a day, but Swift detected at least seven powerful eruptions over a period of about two weeks,” said Stephen Drake, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who gave a presentation on the “superflare” at the August meeting of the American Astronomical Society’s High Energy Astrophysics Division. “This was a very complex event.”

    At its peak, the flare reached temperatures of 360 million degrees Fahrenheit (200 million Celsius), more than 12 times hotter than the center of the sun.


    In April 2014, NASA’s Swift mission detected a massive superflare from a red dwarf star in the binary system DG CVn, located about 60 light-years away. Astronomers Rachel Osten of the Space Telescope Science Institute and Stephen Drake of NASA Goddard discuss this remarkable event.
    Image Credit: NASA’s Goddard Space Flight Center/S. Wiessinger

    The “superflare” came from one of the stars in a close binary system known as DG Canum Venaticorum, or DG CVn for short, located about 60 light-years away. Both stars are dim red dwarfs with masses and sizes about one-third of our sun’s. They orbit each other at about three times Earth’s average distance from the sun, which is too close for Swift to determine which star erupted.

    “This system is poorly studied because it wasn’t on our watch list of stars capable of producing large flares,” said Rachel Osten, an astronomer at the Space Telescope Science Institute in Baltimore and a deputy project scientist for NASA’s James Webb Space Telescope, now under construction. “We had no idea DG CVn had this in it.”

    Most of the stars lying within about 100 light-years of the solar system are, like the sun, middle-aged. But a thousand or so young red dwarfs born elsewhere drift through this region, and these stars give astronomers their best opportunity for detailed study of the high-energy activity that typically accompanies stellar youth. Astronomers estimate DG CVn was born about 30 million years ago, which makes it less than 0.7 percent the age of the solar system.

    Stars erupt with flares for the same reason the sun does. Around active regions of the star’s atmosphere, magnetic fields become twisted and distorted. Much like winding up a rubber band, these allow the fields to accumulate energy. Eventually a process called magnetic reconnection destabilizes the fields, resulting in the explosive release of the stored energy we see as a flare. The outburst emits radiation across the electromagnetic spectrum, from radio waves to visible, ultraviolet and X-ray light.

    At 5:07 p.m. EDT on April 23, the rising tide of X-rays from DG CVn’s superflare triggered Swift’s Burst Alert Telescope (BAT). Within several seconds of detecting a strong burst of radiation, the BAT calculates an initial position, decides whether the activity merits investigation by other instruments and, if so, sends the position to the spacecraft. In this case, Swift turned to observe the source in greater detail, and, at the same time, notified astronomers around the globe that a powerful outburst was in progress.

    “For about three minutes after the BAT trigger, the superflare’s X-ray brightness was greater than the combined luminosity of both stars at all wavelengths under normal conditions,” noted Goddard’s Adam Kowalski, who is leading a detailed study on the event. “Flares this large from red dwarfs are exceedingly rare.”

    The star’s brightness in visible and ultraviolet light, measured both by ground-based observatories and Swift’s Optical/Ultraviolet Telescope, rose by 10 and 100 times, respectively. The initial flare’s X-ray output, as measured by Swift’s X-Ray Telescope, puts even the most intense solar activity recorded to shame.

    The largest solar explosions are classified as extraordinary, or X class, solar flares based on their X-ray emission. “The biggest flare we’ve ever seen from the sun occurred in November 2003 and is rated as X 45,” explained Drake. “The flare on DG CVn, if viewed from a planet the same distance as Earth is from the sun, would have been roughly 10,000 times greater than this, with a rating of about X 100,000.”

    But it wasn’t over yet. Three hours after the initial outburst, with X-rays on the downswing, the system exploded with another flare nearly as intense as the first. These first two explosions may be an example of “sympathetic” flaring often seen on the sun, where an outburst in one active region triggers a blast in another.

    Over the next 11 days, Swift detected a series of successively weaker blasts. Osten compares the dwindling series of flares to the cascade of aftershocks following a major earthquake. All told, the star took a total of 20 days to settle back to its normal level of X-ray emission.

    How can a star just a third the size of the sun produce such a giant eruption? The key factor is its rapid spin, a crucial ingredient for amplifying magnetic fields. The flaring star in DG CVn rotates in under a day, about 30 or more times faster than our sun. The sun also rotated much faster in its youth and may well have produced superflares of its own, but, fortunately for us, it no longer appears capable of doing so.

    Astronomers are now analyzing data from the DG CVn flares to better understand the event in particular and young stars in general. They suspect the system likely unleashes numerous smaller but more frequent flares and plan to keep tabs on its future eruptions with the help of NASA’s Swift.

    See the full article, with video, here.

    The Swift Gamma-Ray Burst Mission consists of a robotic spacecraft called Swift, which was launched into orbit on November 20, 2004, at 17:16:00 UTC on a Delta II 7320-10C expendable launch vehicle. Swift is managed by the NASA Goddard Space Flight Center, and was developed by an international consortium from the United States, United Kingdom, and Italy. It is part of NASA’s Medium Explorer Program (MIDEX).


    ScienceSprings is powered by MAINGEAR computers

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