Astronomy Picture of the Day

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 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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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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NASA Official: Jay Norris. Specific rights apply.
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& Michigan Tech. U.

Publications with keywords: black hole - accretion disk
Publications with words: black hole - accretion disk
See also:

• Possible Jet Blown Shells Near Microquasar Cygnus X1
• At the Center of the Milky Way
• Black Hole Candidate Cygnus X 1
• M81: Feeding a Black Hole
• Jumbled Galaxy Centaurus A
• Sgr A*: Fast Stars Near the Galactic Center
• The Center of Centaurus A

All publications on this topic >>