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47 Tucanae:
Chandra Reveals Nest of Tight Binaries in Dense Cluster
47 Tuc X-ray Image
These Chandra images provide the
first complete census of compact binary stars in the
core of the globular cluster known as 47
Tucanae. As the oldest stellar systems in the
Milky Way Galaxy, globular clusters are laboratories
for stellar and dynamical evolution. Nearly all objects
in the Chandra images are "binary systems," in which a
normal, Sun-like star companion orbits a collapsed
star, either a white dwarf or neutron star. The data
also reveal the presence of "millisecond pulsars" that
rotate extremely rapidly, between 100 to nearly 1000
times a second. The relative numbers and components of
the binary systems tell scientists about the formation
and evolution of the globular cluster.
In a region of the sky equivalent to 1/15th the
diameter of the Full Moon, the Chandra image on the
left shows over 100 X-ray sources, more than ten times
found by previous X-ray satellites. Astronomers have
long studied 47 Tucanae, but Chandra is the first X-ray
satellite with enough the spatial resolution and
sensitivity to detect all of these objects. The image
on the right is a blow-up view of the central region of
the Chandra field to the left. The different colors in
the Chandra image represent the dominant X-ray energy
range for each source: low-energy X-ray emission (red
sources), intermediate energy X-ray emission (green
sources), and high-energy X-ray emission (blue
sources). The white sources are bright in each energy
range. The faint red sources are mostly millisecond
pulsars, while the bright white sources are mostly
binaries containing white dwarfs pulling matter off
normal stars. The two blue sources are also binaries
containing white dwarfs. Pairs of normal stars that
have undergone large flares induced by their close
proximity are shown as objects with a mixture of red
and white.
| Fast Facts for 47 Tucanae: |
| Credit |
NASA/CfA/J.Grindlay et al. |
| Scale |
Left is 2 arcmin per side: Right 0.6 arcmin per side. |
| Category |
Neutron Stars/X-ray Binaries |
| Coordinates (J2000) |
RA 00h 24m 42.0s | Dec -72° 00' 00 |
| Constellation |
Tucana |
| Observation Dates |
March 16-17, 2000
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| Observation Time |
21 hours |
| Obs. IDs |
98, 953, 954, 955, 956
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| Color Code |
Intensity |
| Instrument |
ACIS |
| Release Date |
May 17, 2001 |
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