Hubble Observes Spiral Gas Disk In Active Galaxy

NASA's Hubble Space Telescope has obtained this image of a spiral-shaped disk of hot gas in the core of active giant elliptical galaxy M87. HST measurements show the disk is rotating so rapidly as it contains a massive dense object at its hub. This central object weights as much as three billion suns, but is concentrated in a volume of at most a few light-years diameter.

Now that astronomers have seen the signature of the tremendous gravitational field at the center of M87, it is probable that the region contains only a fraction of the number of stars that would be necessary to create such a powerful attraction. Earlier observations suggested the presence of such a supermasive object, but were not decisive. Many astronomers believe that this object may be a supermassive black hole. If it should be a black hole, it would be an object that is so massive yet compact nothing can escape its gravitational pull, not even light. The object at the center of M87, which weights as much as three billion suns, would then be concentrated into a space no larger than our solar system.

A brilliant jet of high-speed electrons that emits from the nucleus (diagonal line across image) is believed to be produced by the "central engine."

The image was taken with HST's Wide Field Planetary Camera 2.

Credit: Holland Ford, Space Telescope Science Institute/John 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.

Original Press Release STScI-PR94-23a

Hubble Measures Velocity Of Gas Orbiting M87's Massive Central Object

A schematic diagram of velocity measurements of 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 -- as part of the swirling disk spins in earth's direction and the other side spins away from earth. 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 viewers on Earth.

This high velocity is the signature of the tremendous gravitational field at the center of M87. This is clear evidence that the region harbors a supermassive object, since it probably contains only a fraction of the number of stars that would be necessary to create such a powerful attraction.

The observations were made with HST's Faint Object Spectrograph.

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.

HST image of M87's Jet (July 2000)

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Hartmut Frommert
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Last Modification: 24 Jun 1999