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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.

See Explanation. Clicking on the picture will download the largest version available.

Galactic Center Flicker Indicates Black Hole

Explanation: Why would the center of our Galaxy flicker? Many astronomers believe the only credible answer involves a black hole . During observations of Sagittarius A* with the orbiting Chandra X-ray Observatory , the bright X-ray source at the very center of our Milky Way brightened dramatically for a few minutes. Sagittarius A* is visible as the bright dot near the center of the above image . Since large objects cannot vary quickly, a small source is implicated in the variation. Evidence including the motions of central stars indicates that the center of our Galaxy is a massive place, however, estimated to be over a million times the mass of our Sun . Only one known type of object can fit so much mass in so small a volume: a black hole . This short flicker therefore provides additional evidence that a black hole does indeed reside at our Galaxy's center . If true, the flicker might have been caused by an object disrupting as it fell toward the disruptive monster .

Date September 10, 2001
Credit Credit: F. Baganoff ( MIT ) et al., CXO , NASA
Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
A service of: ASD at NASA / GSFC,
NASA Science Activation & Michigan Tech. U.