Astronomers have detected the fastest known star in the Milky Way, S301, which is hurtling around the supermassive black hole, Sagittarius A*, at the galaxy's centre. The star travels at about 25,000km per second, which is 100,000 times faster than a commercial plane.
S301 is also the closest known star to Sagittarius A*, approaching it at a distance comparable to Saturn's orbit around the Sun. Felix Mang, a PhD student at the Max Planck Institute for Extraterrestrial Physics (MPE) and an author of the study, stated that the star's tight orbit, taking just 8.7 years to complete, is unprecedented.
The star's extreme proximity to Sagittarius A* could offer new insights into the black hole's fundamental properties and its surrounding environment. Dr Stefan Gillessen, a senior scientist at MPE and co-author of the study published in Nature, noted that this could allow for the first direct measurement of a massive black hole's spin, providing a key test of Einstein's general theory of relativity.
Observations were made using the European Southern Observatory’s Very Large Telescope Interferometer (ESO’s VLTI) in Chile. Scientists have traced S301's orbit back to 2017 and anticipate having sufficient data by its next closest passage in 2031 to measure the black hole's spin.