In our Galaxy of about 100 billion stars, a supernova occurs, on the average, once in every 100 years. For this reason, much of the research in supernovae has been done in galaxies external to our own. It is possible we may experience a supernova within our galaxy in the course of our lifetimes. Until that time, we must content ourselves with a search for the remains of previous supernovae. When a star does supernova, it radiates more energy than a billion Suns and ejects matter at close to the velocity of light for a period of about two weeks!

The expanding shell of debris creates a nebula that for hundreds, even thousands of years radiates vigorously in both the x-ray and radio regions of the spectrum. About 2 dozen of these remains of past supernovae or supernovae remnants have been discovered in our galaxy. Four of the remnants have been identified with supernovae whose sudden appearance in the sky can be found in historical records: A.D. 1006, 1054 Crab Nebula), 1572 (Tycho's Nova) and 1604 (Kepler's Nova) -- all prior to the telescope. Some of the most intense discrete radio and x-ray sources are associatled with supernovae remnants. As pointed out earlier in this article, many supernovae remnants contain a rapidly rotating super-dense neutron star called a pulsar. For more information, and the positions of galactic remnants, see Radio, X-ray, Pulsar sections of this series. (Also see the diagram of the supernovae list).

Copyright (c) 1997-99 Michael Erlewine