spacetoday.net: Astronomers find new evidence for Milky Way black hole

Posted: Thu, Oct 17, 2002, 7:57 AM ET (1157 GMT)
Astronomers announced Wednesday that they have found new evidence supporting the hypothesis that the center of the Milky Way is home to a supermassive black hole. In a paper published in the latest issue of the journal Nature, scientists reported that they had discovered a star orbiting the center of the galaxy. Observations of the star over a decade allowed astronomers to track it over two-thirds of its orbit, during which time it came within 17 light-hours — 18.4 billion kilometers of the center — of the center. The only object that is both massive enough to account for the star's motion yet compact enough to allow the star to pass that close is a supermassive black hole, astronomers conclude. The black hole is up to 3.7 million times as massive as the Sun. Astronomers had long suspected that there was such a black hole in the core of the galaxy, but could not rule out alternatives, such as clusters of neutron stars.