Star Clusters

Gravitationally associated groups of many stars that formed together, split by the discipline into open clusters, loose groups of young stars still near their birth nebula, and globular clusters, dense and ancient spherical swarms orbiting a galaxys halo, plus asterisms and star clouds recognized as informal groupings. Belongs here: any entry describing the cluster or grouping as a whole. Does not belong here: an individual star within a cluster catalogued on its own, grouped under Stars.