Giant diffuse galaxy

A giant diffuse galaxy is a supermassive, elliptical galaxy that is usually located in the centre of a cluster of galaxies. The term is often contracted to cD galaxies or BCGs (for brightest cluster galaxies). Giant diffuse galaxies are on average about 10 times more luminous than "regular" galaxies, and many times larger than a normal elliptical galaxy - some having diameters of over 6 million light years (the Milky Way, in contrast, is thought to be only around 100 thousand light years across). Giant diffuse galaxies are usually the largest galaxies in their respective clusters.
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