Gas Orbiting a Black Hole?

A schematic diagram of velocity measurements for a rotating disk of hot gas in the core of active galaxy M87. The measurement was made by studying how the light from the disk is redshifted and blueshifted (the Doppler effect) using the Faint Object Spectrograph aboard the Hubble Space Telescope: part of the swirling disk spins in Earth's direction and the other side spins away from Earth, thus causing opposite Doppler shifts. The gas on one side of the disk is speeding away from Earth, at a speed of about 1.2 million miles per hour (550 kilometers per second). The gas on the other side of the disk is orbiting around at the same speed, but in the opposite direction, as it approaches the Earth.

This high velocity indicates the presence of a tremendous gravitational field at the center of M87, and is clear evidence that the region harbors a massive black hole, since it contains only a fraction of the number of visible stars that would be necessary to create such a powerful attraction in a region that is no larger than the Solar System.

Credit: Holland Ford, Space Telescope Science Institute/Johns Hopkins University; Richard Harms, Applied Research Corp.; Zlatan Tsvetanov, Arthur Davidsen, and Gerard Kriss at Johns Hopkins; Ralph Bohlin and George Hartig at Space Telescope Science Institute; Linda Dressel and Ajay K. Kochhar at Applied Research Corp. in Landover, Md.; and Bruce Margon from the University of Washington in Seattle.
NASA
PHOTO CAPTION STScI-PR94-23b