The Sombrero Galaxy and a Swarm of Globular Clusters
Copyright: Rolf Wahl Olsen
Orbiting the Sombrero galaxy is one of the largest known populations of globular clusters, containing up to 1900 members. In comparison our own Milky Way galaxy has only around 150-200 such clusters.
Highlighted in this image are 136 of the Sombrero's brightest globulars, ranging in magnitudes from 17.5 to 22+. Some of these globulars are very large and one is classified as a separate Ultra Compact Dwarf galaxy, SUCD1, the closest known example of such an object. It is not known how the Sombrero amassed such a large number of globular clusters. This is normally a more typical feature of large elliptical galaxies. For example up to 12,000 globular clusters are orbiting the giant elliptical galaxy Messier 87.
In the background numerous distant galaxies can be seen, many of them clumped together in groups. Also, what appears to be a faint tidal tail of the Sombrero is visible near the middle of the bottom edge of the image (between globulars #82 and #99). This is likely an ancient remnant trail of a captured dwarf galaxy.
Link to annotated full resolution image (1MB) is here: http://www.pbase.com/rolfolsen/image/143968106/original
(Including list with details of all 136 globulars)