... A Black Hole in M87's Center? ... In this 1994 photograph by the Hubble Space Telescope , a disk of hot gas was found to be orbiting at the center of this massive elliptical galaxy . ... The rotation speed of gas in this disk indicates the mass of the object the gas is orbiting, while the size of the disk indicates an approximate volume of the central object. These observations yield a central density so high that the only hypothesized object that could live there is a black hole . ...