Astronomy Picture of the Day Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2014 March 23 The View Near a Black Hole Illustration Credit:April Hobart, CXC Explanation: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 gasfrequently indicate not only that a black holeis present, but also likely attributes. The gas surrounding GRO J1655-40, for example, has been found to display an unusual flickeringat a rate of 450 times a second. Given a previous mass estimatefor the central objectof seven times the mass of our Sun, the rate of the fast flickeringcan be explainedby a black holethat is rotatingvery rapidly. What physical mechanisms actually cause the flickering-- and a slower quasi-periodic oscillation(QPO) -- in accretion diskssurrounding black holesand neutron starsremains a topic of much research.
Posted on: Sun, 23 Mar 2014 05:25:22 +0000
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