Milky Way’s fastest star found near black hole

Astronomers have discovered a star they describe as the fastest detected in the Milky Way, orbiting the supermassive black hole at the centre of the galaxy at up to 25,000 kilometres per second.

The star, named S301, circles Sagittarius A* on a tight 8.7-year orbit. Researchers said it gets roughly as close to the black hole as Saturn is to the Sun.

The team used the European Southern Observatory's Very Large Telescope in Chile to identify the star, which they first noticed in 2023 and have tracked since then. Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics said the discovery followed decades of monitoring stars around Sagittarius A*.

Scientists believe S301 may help test Albert Einstein's theory of general relativity and measure the black hole's spin. The team expects another close look when the star makes its next closest approach in 2031.

Researchers also believe S301 was once part of a binary star system torn apart by the black hole's pull, leaving S301 trapped while its partner star was likely flung out of the galaxy.

The study was published in Nature on Wednesday.