NGC 4594, Sombrero Galaxy
In the constellation Virgo
660 million times the mass of the Sun
Diameter larger than the orbit of Saturn
Messier 104 is one of the most photogenic galaxies in the nearby universe. The large spiral is turned almost edge-on as seen from Earth, and a dark lane of dust outlines the galaxy's edge, giving M104 a distinctive nickname: the Sombrero galaxy.
The hat's "crown" is a large bulge of old stars in the galaxy's middle. And beneath the crown is a supermassive black hole more tha 600 million times as massive as the Sun.
Astronomer John Kormendy discovered the black hole in 1988. Using the Canada-France-Hawaii Telescope in Hawaii, he measured the motions of stars at different distances from the galaxy's center. The difference in speed indicated that the stars are orbiting a supermassive black hole -- just the third black hole discovered with this technique.
Follow-up observations with the vision-corrected Hubble Space Telescope in the 1990s confirmed black hole by providing a view five times sharper than that of the ground-based telescope alone. Subsequent observations with HST and several ground-based telescopes have allowed astronomers to narrow the range of possible masses for the black hole.
M104 is also a strong source of X-rays and a type of radio waves. The X-rays may be produced by a disk of superhot gas around the black hole, while the radio waves are probably produced by "jets" of particles from the disk that are shot into space by magnetic fields around the black hole.
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This document was last modified: April 30, 2012.