The Centaurus Cluster (A3526) is a cluster of hundreds of galaxies

Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...

, located approximately 155 million light years away in the Centaurus

Centaurus

Centaurus is a bright constellation in the southern sky. One of the largest constellations, Centaurus was included among the 48 constellations listed by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations.-Stars:...

 constellation. The brightest member galaxy is the elliptical galaxy

Elliptical galaxy

An elliptical galaxy is a galaxy having an approximately ellipsoidal shape and a smooth, nearly featureless brightness profile. They range in shape from nearly spherical to highly flat and in size from hundreds of millions to over one trillion stars...

 NGC 4696

NGC 4696

NGC 4696 is an elliptical galaxy. It lies around 150 million light years away in the constellation Centaurus. It is the brightest galaxy in the Centaurus Cluster, a large, rich cluster of galaxies in the constellation of the same name. The galaxy is surrounded by many dwarf elliptical galaxies...

 (~11m). The Centaurus cluster shares its supercluster, the Hydra-Centaurus Supercluster

Hydra-Centaurus Supercluster

The Hydra-Centaurus Supercluster , or the Hydra and Centaurus superclusters, is a supercluster in two parts and the closest neighbour of Milky Way's Virgo Supercluster....

, with IC4329 Cluster and Hydra Cluster

Hydra Cluster

The Hydra Cluster is a cluster of galaxies that contains 157 bright galaxies and can be viewed from earth in the constellation Hydra. The cluster spans about ten million light years and has an unusual high proportion of dark matter. The cluster is part of the Hydra-Centaurus Supercluster located...

.

The cluster consists of two different sub-groups of galaxies with different velocities. Cen 30 is the main subgroup containing NGC 4696

NGC 4696

NGC 4696 is an elliptical galaxy. It lies around 150 million light years away in the constellation Centaurus. It is the brightest galaxy in the Centaurus Cluster, a large, rich cluster of galaxies in the constellation of the same name. The galaxy is surrounded by many dwarf elliptical galaxies...

. Cen 45 is moving at 1500 km/s relative to Cen 30, and is believed to be merging with the main cluster.