Galaxy group

A galaxy group^[2] or group of galaxies^[3] (GrG^[4]) is an aggregation of galaxies comprising about 50 or fewer gravitationally bound members, each at least as luminous as the Milky Way (about 10¹⁰ times the luminosity of the Sun); collections of galaxies larger than groups that are first-order clustering are called galaxy clusters.^[5] The groups and clusters of galaxies can themselves be clustered, into superclusters of galaxies.

The Milky Way galaxy is part of a group of galaxies called the Local Group.^[6]

^ "Hubble views a bizarre cosmic quartet". Retrieved 19 June 2015.
^ Bärbel Koribalski (2004). "The NGC 6221/15 Galaxy Group".
^ Hartmut Frommert & Christine Kronberg. "Groups and Clusters of Galaxies with Messier objects". SEDS.
^ "Object classification in SIMBAD". SIMBAD. November 2013.
^ Sparke, L. S. & Gallagher, J. S. (2007). Galaxies in the Universe: an Introduction (2nd ed.). Cambridge University Press. p. 278. ISBN 9780521671866.
^ Mike Irwin. "The Local Group". Retrieved 2009-11-07.

[1] "Hubble views a bizarre cosmic quartet". Retrieved 19 June 2015.

[2] Bärbel Koribalski (2004). "The NGC 6221/15 Galaxy Group".

[3] Hartmut Frommert & Christine Kronberg. "Groups and Clusters of Galaxies with Messier objects". SEDS.

[4] "Object classification in SIMBAD". SIMBAD. November 2013.

[5] Sparke, L. S. & Gallagher, J. S. (2007). Galaxies in the Universe: an Introduction (2nd ed.). Cambridge University Press. p. 278. ISBN 9780521671866.

[MikeIrwin-LocalGroup-2009-6] Mike Irwin. "The Local Group". Retrieved 2009-11-07.

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