Smithsonian Astrophysical Observatory - 30 April 2010
The Triangulum Galaxy, at a distance of only 2.6 million light-years, is one of the closest spiral galaxies to earth. It is also the third largest member of our galactic neighborhood (after Andromeda and our own Milky Way). Because we see it nearly face on and so have such a clear view of its stars, it has long been an obvious choice for astronomers wanting to characterize the complete population of supernovae in a galaxy.
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The scientists detected eighty-two of the 137 known supernova remnants, making this the largest sample of supernova remnants detected both in optical and X-rays in any galaxy, including the Milky Way. They developed a new morphological classification scheme to relate optical and X-ray sources, reported that they find no direct analogs to some of the bright, recent remnants in the Milky Way, and concluded that there are no strong correlations between the X-ray brightness of these remnants and their brightnesses at other wavelengths. The results refine our basic understanding of supernovae, and help clarify the range of X-ray properties they have.