| Themes > Science > Astronomy > The Galaxies > Groups, Clusters, and Superclusters of Galaxies > The Virgo and Coma Rich Clusters |
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The Virgo Rich ClusterThe Virgo Cluster of galaxies lies at a distance of about 16 Mpc, near the intersection of the constellations Virgo and Coma Berenices. It is an irregular rich cluster containing approximately 250 large galaxies and 2000 small galaxies that covers approximately a 10 x 10 degree patch of our sky (corresponding to a width of about 3 Mpc). Here is a listing of many galaxies in the Virgo Cluster.Irregular rich clusters tend to have a variety of galaxy types. This is true ofthe Virgo Cluster, which contains more spirals than ellipticals, but ellipticals (mostly dwarf ellipticals) are increasingly common near the center. Although spirals are more numerous (65% of the 205 brightest galaxies in the Virgo Cluster are spirals), the 4 brightest galaxies are giant ellipticals, with M87 being the largest and brightest of these. As we shall discuss further below, clusters like Virgo also contain large amounts of hot gas between the galaxies, and large amounts of unseen dark matter. The Coma Rich ClusterThe nearest regular rich cluster lies approximately 15 degrees north of the Virgo Cluster in the constellation Coma Berenices. The Coma Cluster is at a distance of about 90 Mpc and has an angular diameter of about 4 degrees on the celestial sphere as observed from Earth (corresponding to a physical diameter of ~ 6 Mpc). It contains approximately 10,000 galaxies, most of which are faint dwarf ellipticals. The brightest galaxies are mostly ellipticals and class S0 (only about 15% of the brightest 1000 galaxies are spirals or irregulars). This predominance of ellipticals is typical of rich, regular clusters. |
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