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    Category Astronomy/Space

    Hubble sees a Supermassive and Super-Hungry Galaxy

    January 12, 2016, Categories  Astronomy/Space

    Hubble sees a supermassive and super-hungry galaxy

    This NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 4845, constellation Virgo. Credit: ESA/Hubble & NASA and S. Smartt (Queen’s University Belfast)

    Spiral galaxy NGC 4845 is seen >65 million light-years away in the constellation of Virgo. The galaxy’s orientation clearly reveals the galaxy’s striking spiral structure: a flat and dust-mottled disk surrounding a bright galactic bulge. NGC 4845’s glowing center hosts a gigantic version of a black hole, known as a supermassive black hole. The presence of a black hole in a distant galaxy like NGC 4845 can be inferred from its effect on the galaxy’s innermost stars; these stars experience a strong gravitational pull from the black hole and whizz around the galaxy’s center much faster than otherwise.

    From investigating the m...

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    NASA’s Fermi Gamma-ray Space Telescope Sharpens high-energy Vision

    January 11, 2016, Categories  Astronomy/Space

    This image, constructed from more than six years of observations by NASA's Fermi Gamma-ray Space Telescope, is the first to show how the entire sky appears at energies between 50 billion (GeV) and 2 trillion electron volts (TeV). For comparison, the energy of visible light falls between about 2 and 3 electron volts. A diffuse glow fills the sky and is brightest in the middle of the map, along the central plane of our galaxy. The famous Fermi Bubbles, first detected in 2010, appear as red extensions north and south of the galactic center and are much more pronounced at these energies. Discrete gamma-ray sources include pulsar wind nebulae and supernova remnants within our galaxy, as well as distant galaxies called blazars powered by supermassive black holes. Labels show the highest-energy sources, all located within our galaxy and emitting gamma rays exceeding 1 TeV. Credit: NASA/DOE/Fermi LAT Collaboration

    This image, constructed from more than six years of observations by NASA’s Fermi Gamma-ray Space Telescope, is the first to show how the entire sky appears at energies between 50 billion (GeV) and 2 trillion electron volts (TeV). For comparison, the energy of visible light falls between about 2 and 3 electron volts. A diffuse glow fills the sky and is brightest in the middle of the map, along the central plane of our galaxy. The famous Fermi Bubbles, first detected in 2010, appear as red extensions north and south of the galactic center and are much more pronounced at these energies. Discrete gamma-ray sources include pulsar wind nebulae and supernova remnants within our galaxy, as well as distant galaxies called blazars powered by supermassive black holes...

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    Scientists have now measured a Crucial Fusion Reaction, involving H and a rare Isotope of Oxygen, 17O, that occurs inside stars

    January 11, 2016, Categories  Physics, Astronomy/Space

    Coincidence spectrometer employed in the present work. The HPGe crystal (yellow) is located in close geometry to the target. Both the target and the HPGe detector are surrounded by a 16-segment NaI(Tl) annulus (green). The five-sided plastic scintillators used to reject cosmic-ray muons are not shown.

    Coincidence spectrometer employed in the present work. The HPGe crystal (yellow) is located in close geometry to the target. Both the target and the HPGe detector are surrounded by a 16-segment NaI(Tl) annulus (green). The five-sided plastic scintillators used to reject cosmic-ray muons are not shown.

    Stars shine because nuclear reactions in their interiors convert mass to energy at a rate of many million tons/ s. At the same time, these nuclear reactions change the composition of the matter in the stellar interior. Thermonuclear fusion takes place quiescently in stars that are much older than the Sun, and also explosively in novae and supernovae. To explain how stars work, we need to measure the rates of the important nuclear reactions...

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    Quiet Quasar has Apparently Eaten its Fill

    January 10, 2016, Categories  Astronomy/Space

    This is an artist's conception of the "changing-look quasar" as is appared in early 2015. The glowing blue region shows the last of the gas being swallowed by central black hole as it shuts off. The spectrum is the previous one obtained by the SDSS in 2003. Credit: Dana Berry / SkyWorks Digital, Inc.

    This is an artist’s conception of the “changing-look quasar” as is appared in early 2015. The glowing blue region shows the last of the gas being swallowed by central black hole as it shuts off. The spectrum is the previous one obtained by the SDSS in 2003. Credit: Dana Berry / SkyWorks Digital, Inc.

    Astronomers have announced that a distant quasar ran out of gas. Their conclusions clarify why quasar SDSS J1011+5442 changed so dramatically in the handful of years between observations. “We are used to thinking of the sky as unchanging,” said University of Washington astronomy professor Scott Anderson. “The SDSS gives us a great opportunity to see that change as it happens.”

    Quasars are the compact area at the center of large galaxies, usually surrounding a massive black hole...

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