Hercules Cluster of Galaxies

This is a 2048x2048 CCD image of the Hercules cluster. This cluster has a recessional velocity of 11,000 km/s. It is noteworthy in that it contains a number of spiral galaxies, many of which are intereacting. This is a sure sign that the cluster still has substructure and is not fully virialized yet.

Coma Cluster of Galaxies

This is a 2048x2048 CCD image of the Coma Cluster. This cluster has a recessional velocity of about 7000 km/s and is the densest cluster in our local region of the Universe. In contrast to the Hercules cluster, Coma has almost no spiral galaxies in its central regions. The cluster is strongly virialized and has a hot intracluster medium which generates strong X-ray emission. This image shows the central few 100 kpc of the Coma cluster. At a slightly larger radius , images reveal that Coma is still rather devoid of spiral galaxies. It is generally believed that the cold hydrogen gas in the disks of spiral galaxies is swept out of them as they orbit through the intracluster medium of Coma.

HST picture of intermediate redshift cluster

Distant HST Cluster ___________________________________________________________________