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Supernova Remnant
The gaseous shell ejected by a supernova plows into the surrounding interstellar medium, compresses it, intermingles with it, enriches it with freshly synthesized heavy elements, and forms what is called a supernova remnant.
Supernova remnants may be observed for hundreds of thousands of years as often beautiful, visual objects, but also as emitters of radio waves and X-rays.
Close to 150 supernova remnants have been detected in the Milky Way and more than a hundred are being discovered every year in distant galaxies.
Approximately half a dozen supernova remnants have been associated in the Milky Way with supernovae observed during historic times, such as Tycho's and Kepler's supernovae, which were observed in 1572 AD and 1604 AD, and the supernova of 1054 AD.
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ROSAT X-ray image of a supernova remnant in the constellation Cygnus, known as the Cygnus Loop. The supernova exploded about 15,000 years ago at a distance of roughly 2,500 light-years. The image illustrates that even today, the shock wave from the explosion pushes violently into the surrounding interstellar medium and heats the gas to the point of X-ray emission. ROSAT, which is short for Röntgen Satellite, is an X-ray observatory developed by Germany, the US, and the United Kingdom. It was launched in 1990. Image Credit: Levenson et al. and Laboratory for High Energy Astrophysics at NASA/GSFC. |
