A Tour of Abell 2142

Narrator (April Jubett, CXC): Astronomers have used data from NASA's Chandra X-ray Observatory to capture a dramatic image of an enormous tail of hot gas. This tail stretches for more than a million light years behind a group of galaxies that is falling into the depths of an even-larger cluster of galaxies. Discoveries like this help astronomers learn about the environment and conditions under which the Universe's biggest structures evolve.

Galaxy clusters are the largest structures in the Universe held together by gravity. While galaxy clusters can contain hundreds or even thousands of individual galaxies, the lion's share of mass in a galaxy cluster comes from hot gas, which gives off X-rays, and unseen dark matter. How did these cosmic giants get to be so big?

Scientists have discovered that one way galaxy clusters grow is by capturing other galaxies with their extraordinarily powerful gravity. Abell 2142 is a galaxy cluster that contains hundreds of galaxies immersed in giant reservoirs of multi-million-degree gas. A wide-field view including Chandra data shows that a much smaller group of galaxies is plummeting toward the center of Abell 2142, adding to the enormous heft of this cluster.

Behind this diving galaxy group, astronomers found a remarkable long tail of X-rays that extends for hundreds of thousands of light years. This tail formed when hot gas from the group of galaxies falls is stripped off into Abell 2142, much like leaves from a tree in the fall during a strong gust of wind. The shape and length of the tail tells astronomers about certain properties in the system, such as the strength of the magnetic fields that may be wrapping about the tail.

Galaxy clusters have been one of Chandra's most compelling targets over its nearly two decades of operations in space. Scientists look forward to studying many more in the years to come.