This is an artist's representation of GRO J1655-40, a binary star system observed in April 2005 by Chandra. This binary consists of a black hole and a normal star shown in blue. Gas is being pulled away from the star and falling onto a red disk spinning around the black hole. Some of this gas spirals in towards the black hole, generating copious amounts of light along the way. This infall of matter is only possible if the gas loses some of its energy either through a wind, shown in blue, or friction in the disk.