Artist Nandika Dutt
Digital Art - Digital Art
A galaxy cluster, or cluster of galaxies, is a structure that consists of anywhere from hundreds to thousands of galaxies that are bound together by gravity with typical masses ranging from 1014–1015 solar masses.
They are the largest known gravitationally bound structures in the universe and were believed to be the largest known structures in the universe until the 1980s, when superclusters were discovered.One of the key features of clusters is the intracluster medium (ICM). The ICM consists of heated gas between the galaxies and has a peak temperature between 2–15 keV that is dependent on the total mass of the cluster. Galaxy clusters should not be confused with star clusters, such as open clusters, which are structures of stars within galaxies, or with globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as galaxy group rather than clusters of galaxies. The galaxy groups and clusters can themselves cluster together to form superclusters.
Galaxies love to cluster together! Their mutual gravity can draw galaxies together into a cluster that is several millions of light years across. Some clusters have only a handful of galaxies and are called poor clusters. Other clusters with hundreds to thousands of galaxies are called rich clusters. The low mass of a poor cluster prevents the cluster from holding onto its members tightly. The poor cluster tends to be a bit more irregular in shape than a rich cluster.
February 21st, 2018
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