This composite X-ray (blue)/optical (orange) image of M86 shows gas being swept out of the galaxy to form a long tail more than 200,000 light years in length. Located in the Virgo galaxy cluster, this enormous lenticular or elliptical galaxy is moving at about 3 million miles per hour through diffuse hot gas that pervades the cluster. The supersonic motion of M86 produces pressure that is stripping gas from the galaxy and forming the spectacular tail.
M86 has been pulled into the Virgo galaxy cluster and accelerated to a high speed by the enormous combined gravity of dark matter, hot gas, and hundreds of galaxies that comprise the cluster. The infall of the galaxy into the cluster is an example of the process by which galaxy groups and galaxy clusters form over the course of billions of years.
The galaxy is no longer an "island universe" with an independent existence. It has been captured and its gas is being swept away to mix with the gas of the cluster, leaving an essentially gas-free galaxy orbiting the center of the cluster along with hundreds of other galaxies.
This image covers a field of about 15 x 23 arc min.
Credit: X-ray image: NASA/CXC/SAO/C. Jones, W. Forman & S. Murray.
Optical: Digital Sky Survey/Palomar Observatory
See the images separately:
Last Modification: December 12, 2003