supercluster(redirected from Galactic supercluster)
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Related to Galactic supercluster: Galaxy superclusters
supercluster(soo -per-klus-ter) A loosely bound aggregate of several clusters of galaxies, about 100 megaparsecs in extent. As seen in the sky, different superclusters overlap; their members can be distinguished only after the distances of the constituent galaxies have been determined from a redshift survey. Over a dozen superclusters have been identified, the nearest of which include the Local Supercluster, the Pisces–Perseus supercluster, the Shapley supercluster, and Hydra–Centaurus. Superclusters contain between 2 and 15 rich clusters and have total masses of up to 1016 solar masses. Although the galaxies within each cluster are tightly bound, the clusters' gravitational effect on each other is not sufficient to overcome the expansion of the Universe. Each supercluster is thus growing in extent, although more slowly than the space between the superclusters. The larger superclusters appear to be elongated with no central concentration or axial symmetry, and form parts of filaments that surround empty voids (see large-scale structure).
An association of galaxy clusters and groups, typically composed of a few rich clusters and many poorer groups and isolated galaxies.