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Steve Roy
Media Relations Dept.
Marshall Space Flight Center, Huntsville, AL
steve.roy{at}msfc.nasa.gov
(256) 544-0034

Megan Watzke
Chandra X-ray Observatory Center, CFA, Cambridge, MA
cxcpress{at}cfa.harvard.edu
(617) 496-7998

For release: 03-12-03

Photo release no.: 03-037

Chandra image reveals supernova origin
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NASA's Chandra X-ray Observatory image, left panel, of the supernova 
remnant DEM L71 reveals a hot inner cloud, aqua, of glowing iron and 
silicon surrounded by an outer blast wave. This outer blast wave is 
also visible at optical wavelengths, right panel. Data from the 
Chandra observation show that the central 10-million-degree Celsius 
cloud is the remains of a supernova explosion that destroyed a white 
dwarf star.

DEM L71 presents a textbook example of the double-shock structure 
expected to develop when a star explodes and ejects matter at high 
speeds into the surrounding interstellar gas. The expanding ejecta 
drive an outward-moving shock wave that races ahead of the ejecta into 
the interstellar gas, bright outer rim. The pressure behind this shock 
wave drives an inward-moving shock wave that heats the ejecta, seen as 
the aqua cloud.

The clear separation of the shocked matter and the heated ejecta in 
the Chandra image allowed astronomers to determine the mass and 
composition of the ejecta.  The computed ejected mass was found to be 
comparable to the mass of the Sun. This and the X-ray spectrum, which 
exhibits a high concentration of iron atoms relative to oxygen and 
silicon, convincingly show that the ejecta are the remains of an 
exploded white dwarf star.

The size and temperature of the remnant indicate that it is several 
thousand years old.

Astronomers have identified two major types of supernovas:  Type II, 
in which a massive star explodes; and Type Ia, in which a white dwarf 
star explodes because it has pulled too much material from a nearby 
companion star onto itself. If the mass of the white dwarf becomes
greater than about 1.4 times the mass of the Sun, it becomes unstable 
and is blown apart in a thermonuclear explosion. This was the case in 
DEM L71.

One of the major goals of the study of supernova remnants is to 
determine the type of supernova explosion. The identification of DEM 
L71 as the remnant of an exploded white dwarf, or Type Ia supernova, 
represents a major step forward in understanding more about the ways 
in which stars explode.

The Marshall Center manages the Chandra program. 

Credits: NASA/CXC/Rutgers/J. Hughes et al

http://www1.msfc.nasa.gov/NEWSROOM/news/photos/2003/photos03-037.html

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