Double Cluster
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The Double Cluster, also known as Caldwell 14, consists of the open clusters NGC 869 and NGC 884, which are close together in the constellation Perseus. Both visible to the naked eye, NGC 869 and NGC
The Double Cluster, NGC 869 (above) and NGC 884 (below) with north to the left
The Double Cluster in Perseus (lower left of center, wide angle view)
Star cluster
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A star cluster is a group of stars, that share an origin, formed at roughly the same time and held together by self-gravitation. Two main types of star clusters can be distinguished: globular clusters
Messier 44, a cluster in the constellation of Cancer
The Pleiades, an open cluster dominated by hot blue stars surrounded by reflection nebulosity
The embedded Trapezium cluster seen in X-rays which penetrate the surrounding clouds
The globular cluster Messier 15 photographed by HST