In the Phoenix Cluster, the hot gas near the central elliptical galaxy gives off copious amounts of X-rays and cools quickly over time. This cooling causes gas to flow inward along filaments and form huge numbers of stars when it continues to cool.
NASA/CXC/A. Hobart
The Phoenix Cluster is the most powerful producer of X-rays and one of the largest objects in the universe. This NASA video animation demonstrates how huge numbers of stars take shape inside the cluster. Hot gas, shown in red, actually contains more ordinary matter than all of the other galaxies within the cluster combined. At the center of the Phoenix Cluster, a large elliptical galaxy lurks where the hot gas is ejected, giving off unprecedented levels of X-rays, which have been observed by the orbiting Chandra X-ray telescope. The animation shows how the gas quickly cools by changing to a blue color, and then flows inward along filaments, forming stars at a level never before seen in the central galaxy of a cluster.
