04-19-2011, 01:59 PM
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#42 (permalink)
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The Reforms
Location: Rarely, if ever, here or there, but always in transition
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"The View Near a Black Hole" - drawing: April Hobart, courtesy of the CXC.
Explanation (in full)
Quote:
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In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickering at a rate of 450 times a second. Given a previous mass estimate for the central object of seven times the mass of our Sun, the rate of the fast flickering can be explained by a black hole that is rotating very rapidly. What physical mechanisms actually cause the flickering -- and a slower quasi-periodic oscillation (QPO) -- in accretion disks surrounding black holes and neutron stars remains a topic of much research.
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[ APOD.]
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As human beings, our greatness lies not so much in being able to remake the world (that is the myth of the Atomic Age) as in being able to remake ourselves. —Mohandas K. Gandhi
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