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DEM
L238 and DEM L249: X-ray Evidence Supports Possible New Class Of
Supernova
01/04/07
DEM
L238 and DEM L249 are two supernova remnants in the Large
Magellanic Cloud. X-ray data from NASA's Chandra and ESA's
XMM-Newton observatories suggest that the stars responsible for
these debris fields were unusually young when they were destroyed
by thermonuclear explosions.
The large field-of-view is a
composite image of DEM L238 (right) and DEM L249, Chandra X-ray
data in blue and optical data in white. The inset reveals how DEM
L238 appears in the three bands of X-ray emission (low energy
X-rays are shown in red, medium energies in green and high
energies in blue.) The central region of DEM L238 is green which
indicates that it is rich in iron. This overabundance of iron
identifies this object as a so-called Type Ia supernova, one
possible explosive death of a star.
n a Type Ia supernova,
a white dwarf, the dense final stage in the evolution of a
sun-like star, pulls so much mass from an orbiting companion star
that it cannot support its own weight. The star collapses and
temperatures become high enough for carbon fusion to occur.
Fusion begins throughout the white dwarf almost simultaneously
and an explosion occurs.
A surprising feature of these
images is that the iron in the central regions of DEM L238 and
DEM L249 is much denser that in most Type Ia supernovas. The most
likely explanation for these results is that the white dwarfs
exploded into very dense environments. This implies that the
stars which evolved into the white dwarfs were more massive than
usual, since such stars expel more gas into their surroundings.
These stars would explode in much less time -- about 100 million
years -- than the billions of years that astronomers think Type
Ias typically require.
Credit X-ray:
NASA/CXC/NCSU/K.Borkowski; Optical: NOAO/CTIO/MCELS
Scale
Full field image is 21 arcmin across, Inset image is 8.4 arcmin
across
Category
Supernovas & Supernova Remnants
Coordinates
(J2000) RA 05h 34m 08.80s | Dec -70º 34' 28.00"
Constellation
Dorado
Observation
Date October 25, 2003
Observation
Time 14 hours
Obs.
ID 3908
Color
Code Full field: X-ray: Blue; Optical: Red and Green |
Inset: Red: 0.3-0.7 keV; Green: 0.7-3 keV; Blue: 3-7 keV
Instrument
ACIS
References
Dense, Fe-rich Ejecta in Supernova Remnants DEM L238 and DEM
L249: A New Class of Type Ia Supernova? Borkowski, K.J.,
Hendrick, S.P., Reynolds, S.P., 2006, ApJ, 652, 1259
Distance
Estimate About 160,000 light years (distance to LMC)
Release
Date January 04, 2007
Source
/ Credit: Chandra X-Ray
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