The Coma Cluster
The extensively-studied cluster of galaxies in the Coma constellation, lying near the north galactic pole and about 330 million light years away, contains more than 1000 bright galaxies. Although it is considered a typical cluster at the end of its evolution, this X-ray image shows, for the first time, the merging of the larger, brighter central Coma cluster and a fainter group of galaxies at the lower right.
Briel, U. G., J. P. Henry, and H. Böhringer, Observation of the Coma Cluster of Galaxies with ROSAT during the All-Sky Survey, Astro. & Astrophys. 259, L31-L34 (1992)
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