| | ipedia.com: Groups and clusters of galaxies Article (Site not responding. Last check: 2007-09-05) |
 | | Groups of galaxies are the smallest aggregates of galaxies. |
 | | Since this gas is in approximate equilibrium with the overall cluster gravitational field, its distribution in the cluster traces out the overall cluster gravitational field, and therefore allows calculation of the total mass distribution in the cluster. |
 | | Note: clusters of galaxies should not be confused with star clusters such as galactic clusters and open clusters, which are structures within galaxies, as well as globular clusters, which typically orbit galaxies. |
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