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NGC 4697:
Black Holes in Elliptical Galaxy Point to Wild Youth
Chandra's image of the elliptical galaxy NGC 4697
reveals diffuse hot gas dotted with many point-like
sources. As in the elliptical galaxies, NGC 4649
and NGC 1553, the point-like sources are due to black
holes and neutron stars in binary star systems.
Material pulled off a normal star is heated and emits
X-radiation as it falls toward its black hole or
neutron star companion.
Black holes and neutron stars are the end state of the
brightest and most massive stars. Chandra's detection
of numerous neutron stars and black holes in this and
other elliptical galaxies shows that these galaxies
once contained many very bright, massive stars, in
marked contrast to the present population of low-mass
faint stars that now dominate elliptical
galaxies.
An unusually large number of the binary star X-ray
sources in NGC 4697 are in "globular star clusters,"
round balls of stars in the galaxy that contain about
one million stars in a volume where typically only one
would be found. This suggests that the extraordinarily
dense environment of globular clusters may be a good
place for black holes or neutron stars to capture a
companion star.
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Elliptical Galaxies
NGC 1553 & NGC 4649
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The origin of the hot gas cloud enveloping the galaxy
is not known. One possibility is that the gas lost by
evaporation from normal stars- so-called stellar winds
- is heated by these winds and by supernova
explosions.
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Fast Facts for NGC
4697:
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Credit
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NASA/CXC/UVa/C.Sarazin et al.
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Scale
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Image is 4 arcmin on a side.
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Category
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Normal Galaxies & Starburst Galaxies
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Coordinates
(J2000)
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RA 12h 48m 35s | Dec -05º 47'
21" |
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Constellation
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Virgo
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Observation
Date
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January 15-16, 2000
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Observation
Time
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11 hours
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Obs.
ID
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784
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Color
Code
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Intensity
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Instrument
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ACIS
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Distance
Estimate
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about 40 million light years
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Also Known
As
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PGC 43276
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Release Date
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June 04, 2002
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