Fastest known Milky Way star offers new test of supermassive black hole's spin

Astronomers have discovered the fastest known star in our galaxy, the Milky Way, orbiting the black hole at its center. The star, named S301, was detected with the European Southern Observatory's Very Large Telescope Interferometer (ESO's VLTI) and reaches speeds of 25,000 km/s (15,500 miles per second) as it travels around the four-million-solar-mass black hole. It comes closer to it than any other star observed before, so close that it feels the effects of the black hole's rotation.