Chandra Release - December 20, 2010

Visual Description: Abell 644

The 2-panel composite image features optical and X-ray data of two galaxies.  The dominant colors in the image are shades of blue and white, with a bit of dusky purple. In each of the galaxies, data from NASA's Chandra X-ray Observatory are blue, and optical data from the Sloan Digital Sky survey are colored mostly white, yellow and dusty purple. The galaxy on the left, Abell 644, is in the center of a galaxy cluster that lies about 1.1 billion light years from Earth.  The galaxy looks like a very bright source in a sea of smaller bright spots with a large soft blue glow around it.  On the right is an isolated galaxy named XS04107B6_001, which is located about 900 million light years away. This galaxy has very little blue glow and is a small irregular-looking spiral surrounded by a small smattering of other sources.  At the center of both of these galaxies is a growing supermassive black hole, called an active galactic nucleus (AGN) by astronomers, which is pulling in large quantities of gas.