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XTE J1118+480:
Chandra Pinpoints Edge Of Accretion Disk Around Black Hole
This Chandra X-ray Observatory
image is a spectrum of a black hole, which is similar
to the colorful spectrum of sunlight produced by a
prism. The X-rays of interest are shown here
recorded in the bright stripe that runs rightward and
leftward from the center of the image. These X-rays are
sorted precisely according to their energy with the
highest-energy X-rays near the center of the image and
the lower-energy X-rays farther out. The spectrum was
obtained by using the Low Energy Transmission Grating
(LETG), which intercepts X-rays and changes their
direction by amounts that depend sensitively on the
X-ray energy. The LETG is activated by swinging an
assembly into position behind the mirrors and in front
of the instrument that detects the X-rays. The assembly
holds 540 gold transmission gratings; when in place
behind the mirrors, the gratings intercept the X-rays
reflected from the telescope. The bright spot at the
center is due to a fraction of the X-ray radiation that
is not deflected by the LETG. The spokes that intersect
the central spot and the faint diagonal rays that flank
the spectrum itself are artifacts due to the structure
that supports the LETG grating elements
A team of scientists led by Jeffrey McClintock
(Harvard-Smithsonian Center for Astrophysics) used the
LETG in conjunction with the Advanced CCD Imaging
Spectrometer (ACIS) detector to observe the black hole
binary system known as XTE J1118+480 for 27,000 seconds
on April 18, 2000. This "X-ray nova," so-called because
it undergoes occasional eruptions followed by long
periods of dormancy, contains a Sun-like star orbiting
a black hole.
| Fast Facts for XTE J1118+480: |
| Credit |
NASA/CfA/J.McClintock & M.Garcia |
| Category |
Black Holes |
| Coordinates (J2000) |
RA 11h 18m 10.80s | Dec +48° 02' 12.30 |
| Constellation |
Ursa Major |
| Observation Dates |
April 18, 2000
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| Observation Time |
8 hours |
| Obs. IDs |
1701
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| Color Code |
Intensity |
| Instrument |
LETG |
| Distance Estimate |
About 5,000 light years |
| Release Date |
May 07, 2001 |
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