ROSAT HRI Cygnus Loop Image ROSAT PSPC Cygnus Loop Image
Credit: N. Levenson (Johns Hopkins), S. Snowden (USRA/GSFC)

Shards of a Star: A High-resolution X-ray Image of the Cygnus Loop

The Cygnus Loop is a supernova remnant in the constellation Cygnus. It represents the remains of a star which exploded about 20,000 years old. The image on the above left shows a high resolution X-ray picture which shows the extremely hot (about 1 million degree) gas which is produced as the shards of the star crash into other clouds of gas and dust in the space around the star. This image was obtained by stitching together a number of individual pictures taken with the ROSAT High Resolution Imager detector. Note that the hot gas is generally circular in shape; this suggests that the explosion of the star was spherically symmetric, that is, that the explosion was equally strong in all directions. However, there is a "blowout" region in the south of the loop (toward the bottom in the image above) which probably represents a region in which the surrounding space is of especially low density. The image on the right is a "temperature map" of the hot gas in the Cygnus Loop obtained by the ROSAT Position Sensitive Proportional Counter (PSPC). Cooler material is purple-blue, hotter material is yellow-red (regions of no data are black). This temperature map shows that the interior of the Loop is hotter than the edge. Studies of X-ray emission from supernovae provide a very good way to measure the details of the interaction of the supernova ejecta with the interstellar medium. See the ROSAT Cygnus Loop gallery for more X-ray images.

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Page Author: Dr. Michael F. Corcoran
Last modified May 26, 2001