Second black hole found at the centre of our Galaxy

Links: Astronomy and Astrophysics 423, 155 (2004), Nature news item

A second black hole lurks at the centre of our Galaxy, according to astronomers who have watched a cluster of stars spinning around it. [...] Jean-Pierre Maillard, an astronomer from the Institute of Astrophysics in Paris, France, led a team that looked at a very bright area of the galactic core called IRS 13, previously thought by astronomers to be a single object. Using infrared observations from the Gemini Observatory at the summit of Mauna Kea on the Big Island of Hawaii, they discovered that IRS 13 is in fact a rotating cluster of seven stars, just 0.065 light years across. Adding data from the Hubble Space Telescope and the Chandra X-ray Observatory, they calculated from the movement of the seven stars that they must be orbiting an intermediate-mass black hole, called IRS 13E, which spirals around Sagittarius A* at about 280 kilometres per second.