By Ron Cowen
VANCOUVER, Canada — German astronomers monitoring the motions of 28 stars at the center of the Milky Way galaxy have reported a new, more precise value for the mass of the supermassive black hole believed to lurk there.
The black hole weighs the equivalent of 4.31 million suns, with an uncertainty of plus or minus 0.36 million, Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, reported in Vancouver December 10 at the Texas Symposium on Relativistic Astrophysics. The observations also pinpoint the distance from the Earth to the galaxy’s center at 27,000 light-years.
The findings will appear in an upcoming Astrophysical Journal and currently appear online at http://arxiv.org/abs/0810.4674.