Chandra X-ray Observatory (CXO) image of the central region of the Andromeda Galaxy M31.

This X-ray image shows the central portion of the Andromeda Galaxy. The blue dot in the center of the image is a "cool" million degree X-ray source where Andromeda's massive central object, with the mass of 30 million suns, is located, which many astronomers consider to be a supermassive black hole. The X-rays are produced by matter funneling toward the massive object. Numerous other hotter X-ray sources are also apparent. Most of these are probably due to X-ray binary systems, in which a neutron star (or perhaps a stellar black hole) is in a close orbit around a normal star.

The image was made with Chandra's Advanced CCD Imaging Spectrometer (ACIS).

More info on this image (NASA MSFC and Chandra X-ray Observatory Center)

Chandra has a Closer Look at Andromeda's Center

This image of the central region of the Andromeda Galaxy is a composite of Chandra X-ray data (3 pixilated sources) and Hubble optical data ( red contours). The supermassive central object of M31 lies within the highest optical contour on the lower right. These highly accurate positions show that the very cool X-ray source (blue) previously identified with the supermassive object in the center of the galaxy is actually about 10 light years south of the center. A second, hotter X-ray source, is found to be at a position consistent with the position of the supermassive object.
Credit: X-ray: NASA/SAO/CXC/M. Garcia et al., Optical: NASA/GSFC/T. Brown et al.

Earlier X-ray observations of M31, by Rosat

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Hartmut Frommert
Christine Kronberg
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Last Modification: May 14, 2001