ASTRONOMERS DISCOVER FASTEST STAR ORBITING MILKY WAY BLACK HOLE

Astronomers have discovered the fastest known star in the Milky Way, orbiting the supermassive black hole at the galaxy's centre. Named S301, the star travels at speeds of approximately 25,000 kilometres per second—about 100,000 times faster than a commercial aeroplane—as it circles Sagittarius A*, a black hole with a mass of between 4 and 4.3 million times that of the Sun. The discovery was detected using the European Southern Observatory's Very Large Telescope Interferometer in Chile's Atacama Desert and published in the journal Nature on 19 August.

S301 orbits closer to Sagittarius A* than any star observed previously, completing one revolution every 8.7 years at a distance of approximately 12 times the Earth-to-Sun distance—roughly the distance from Saturn to the Sun. The star's unprecedented proximity means it is the first known star close enough to the black hole to feel the effects of its rotation, rather than only its gravitational mass. According to Einstein's general theory of relativity, spinning black holes drag spacetime around them, an effect that becomes more pronounced at closer distances and higher speeds. Several hundred stars orbit this central black hole, with astronomers having mapped the orbits of approximately 50 of them. S301 is 10 times closer than the previous record holder.

Scientists say the discovery offers a new opportunity to measure the rotational properties of the supermassive black hole, which has remained difficult to determine. Felix Mang, a doctoral student at the Max Planck Institute for Extraterrestrial Physics and the study's author, stated that researchers should be able to measure the black hole's spin rate within about a decade. As telescope technology advances and fainter stars become detectable, astronomers predict that even faster stars may be found orbiting Sagittarius A*.