structure made up of a gravitationally-bound aggregation of about 50 or fewer galaxies; is smaller than a galaxy cluster
A galaxy group is a group of galaxies made up of less than 50 or so members and bound by gravity. Collections of galaxies larger than groups are called galaxy clusters or superclusters. Our own galaxy, the Milky Way, is in the Local Group of more than 40 galaxies.
Galaxy groups are the smallest groups of galaxies. They usually have no more than 50 galaxies. The group in a diameter of 1 to 2 megaparsecs (about 4 to 8 million light-years). Their mass is about 1013 solar masses. This is just a guide, because larger and more massive galaxy systems are sometimes called galaxy groups.
- ↑ Mike Irwin. "The Local Group". Retrieved 2009-11-07.
- ↑ UTK Physics Dept. "Groups of Galaxies". University of Tennessee, Knoville. Retrieved September 27, 2012.