Clusters of Galaxies (3) ...

Abell 2151 in Hercules
The adjacent image shows the cluster of galaxies Abell 2151 in the constellation Hercules. This cluster, which is about 160 Mpc distant, is rich in spiral galaxies with gas and dust and star formation. But it is relatively poor in elliptical galaxies. This indicates that it is a young cluster.

The star forming regions have a bluish cast while the elliptical galaxies are more yellow in color. We can also see evidence for collisions and mergers of galaxies in the cluster (the galaxies that appear distorted or overlapping). These collisions and mergers are presumably altering the content of the cluster, as we shall discuss further in the later module on interacting galaxies in this chapter.