“After tracking its motion for 10 years, astronomers have caught a star careening around the supermassive black hole at the Milky Way’s center. Their observations, reported in tomorrow’s issue of Nature, provide definitive proof that a roughly 2.6-million-solar-mass black hole lurks at the core of our galaxy.” Sky and Telescope
A movie of a star orbiting the black hole, and an explanation of the significance of this finding, are here.
In related news, astronomer sees distant black hole ‘eat’ star. CNN