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Science Forum Index » Astro Forum » NGC 1132: A Mysterious Elliptical Galaxy (Forwarded)
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| Andrew Yee |
 Posted: Fri Apr 18, 2008 11:55 am |
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Guest
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Megan Watzke
Chandra X-ray Center, Cambridge, Mass.
617-496-7998
February 5, 2008
NGC 1132: A Mysterious Elliptical Galaxy
[http://chandra.harvard.edu/photo/2008/ngc1132/]
This image of the elliptical galaxy NGC 1132 and its surrounding region
combines data from NASA's Chandra X-ray Observatory and the Hubble Space
Telescope. The blue/purple in the image is the X-ray glow from hot,
diffuse gas detected by Chandra. Hubble's data reveal a giant foreground
elliptical galaxy, plus numerous dwarf galaxies in its neighborhood, and
many much more distant galaxies in the background.
Astronomers have dubbed NGC 1132 a "fossil group" because it contains an
enormous amount of dark matter, comparable to the dark matter found in an
entire group of galaxies. Also, the large amount of hot gas detected by
Chandra is usually found for groups of galaxies, rather than a single
galaxy.
The origin of such fossil-group systems remains a puzzle. They may be the
end-products of the complete merging of groups of galaxies. Or, they may
be very rare objects that formed in a region or period of time where the
growth of moderate-sized galaxies was somehow suppressed, and only one
large galaxy formed.
Elliptical galaxies are smooth and featureless. Containing hundreds of
millions to trillions of stars, they range from nearly spherical to very
elongated shapes. Their overall yellowish color comes from the aging
stars. Because elliptical galaxies do not contain much cool gas, they can
no longer make large numbers of new stars. |
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