The Shortest-Known–Period Star Orbiting Our Galaxy’s Supermassive Black Hole

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Science  05 Oct 2012:
Vol. 338, Issue 6103, pp. 84-87
DOI: 10.1126/science.1225506

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Close to a Black Hole

At the center of our Galaxy, there is a black hole that is 4 million times as massive as the Sun. Using data from the Keck Observatory, Meyer et al. (p. 84) detected a star orbiting this black hole with a period of 11.5 years, the shortest period among the stars orbiting it. The star is the second well-sampled star with an orbital period under 20 years. Having detailed knowledge about two stars with short periods and full orbit coverage will be crucial in testing Einstein's theory of general relativity in the gravitational field close to a massive black hole.


Stars with short orbital periods at the center of our Galaxy offer a powerful probe of a supermassive black hole. Over the past 17 years, the W. M. Keck Observatory has been used to image the galactic center at the highest angular resolution possible today. By adding to this data set and advancing methodologies, we have detected S0-102, a star orbiting our Galaxy’s supermassive black hole with a period of just 11.5 years. S0-102 doubles the number of known stars with full phase coverage and periods of less than 20 years. It thereby provides the opportunity, with future measurements, to resolve degeneracies in the parameters describing the central gravitational potential and to test Einstein’s theory of general relativity in an unexplored regime.

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