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Press Advisory
Closer Look Reveals Andromeda's Black Hole Not As "Cool" As Believed
October 12, 2001
Steve Roy
Marshall Space Flight Center, Huntsville, AL
Phone: 256-544-6535
Megan Watzke
Chandra X-ray Observatory Center, CfA, Cambridge, MA
Phone: 617-496-7998
On January 14, 2000, a team of astronomers using NASA's Chandra
X-ray Observatory announced the discovery of an unusual source very
near the nucleus of the Andromeda Galaxy, also known as M31. The
proximity of this source to the nucleus, and its extraordinarily low
temperature relative to other X-ray sources in M31, led the
astronomers to associate it with the supermassive black hole located
at the center of M31. These results were extraordinary because they
could not be explained by the standard models developed for
supermassive black holes in galaxies like the Milky Way and
Andromeda. However, recent observations with NASA's Hubble Space
Telescope and analysis of additional Chandra observations of M31 by
the same team have shown that this association was in error.
The team, led by Michael Garcia of the Harvard-Smithsonian Center
for Astrophysics, Cambridge, Mass., has recently detected two X-ray
emitting globular star clusters - so called because of their
spherical shape - in the vicinity of the M31 supermassive black hole.
The globular clusters, which are visible on both Hubble and Chandra
images, can be used as a cross-check to determine the position of all
of the X-ray sources near the supermassive black hole to an accuracy
ten times greater than before.
These new and slightly revised positions show that the very cool
X-ray source is actually located approximately 1 arcsecond south of
the supermassive black hole. A second, hotter X-ray source, is found
to have a location that is consistent with the position of the
super-massive black hole, but the astronomers caution that, due to
the complex nature of the region, it is not possible at this time to
say with certainty that this source is due to the supermassive black
hole.
Images associated with this release are available on the World Wide
Web at:
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