The Galaxy’s Fastest Star Could Reveal the Secrets of a Supermassive Black Hole

Astronomers have identified S301, the fastest known Milky Way star, reaching 25,000 km/s (8% light speed) and completing an 8.7-year orbit that brings it within a Saturn-Sun distance of Sagittarius A*, the galaxy’s four-million-solar-mass black hole. The star’s extreme velocity likely results from a binary disruption that left S301 bound to the black hole while ejecting its companion, and its orbit will enable measurement of Sagittarius A*’s spin within the next decade.