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.

2000 January 20
See Explanation.  Clicking on the picture will download 
 the highest resolution version available.

X-Rays From The Galactic Centre
Credit: G.Garmire (PSU), F. Baganoff (MIT), et al., CXO, NASA

Explanation: Exploring quasars and active galaxies in the distant universe, astronomers have come to believe that most galaxies have massive black holes at their centres. Swirling stars and a strong, variable radio source offer convincing evidence that even our own Milky Way galaxy's centre harbours such a bizarre object, a mere 30,000 light-years away. Still, it has long been realized that if a massive black hole lurks there it should produce X-rays - which have not previously been identified. Now, though relatively faint, the missing X-ray source may have been found. Taking advantage of the sensitive Chandra Observatory astronomers have recorded this false-colour X-ray image of the Galactic Centre. Embedded in a diffuse cloud of X-ray hot gas, the white dot at the centre corresponds to an X-ray source at exactly the position of the strong radio source and suspected black hole. Other individual X-ray sources are also present in the picture which spans about 10 light-years at the distance of the galactic centre. With radio and X-ray emission generated by infalling material, the Milky Way's central black hole is thought to have a mass of over 2 million suns.

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Tomorrow's picture: X For Andromeda

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