Astronomers have discovered the largest stellar black hole in the Milky Way, named Gaia BH3, located 2,000 light-years from Earth. This discovery, recently detailed in Astronomy and Astrophysics, surpasses the previously known black hole, Cygnus X-1.
The European Space Agency’s (ESA) Gaia mission, operational since 2013, enabled this groundbreaking finding. Gaia BH3, situated in the Aquila constellation, boasts a mass 33 times that of our Sun, overshadowing Cygnus X-1’s 21 solar masses.
Pasquale Panuzzo, an astronomer at the Observatoire de Paris and the study’s lead, expressed his initial disbelief to Gizmodo: “When I saw the results for the first time, I was convinced there was a problem in the data. I could not believe it. Now, I feel I’ve discovered my life!”
Scientists knew a star orbiting Gaia BH3 existed, but the revelation of its massive black hole companion was unexpected. Black holes, typically located at the centre of large galaxies, form from the gravitational collapse of massive stars. Their gravitational pull is so strong that no light can escape from within their event horizon.
Moreover, the galactic centre hosts another much larger black hole, Sagittarius A*, with a mass four million times that of the Sun. Unlike Gaia BH3, Sagittarius A* likely formed from the merger of smaller black holes and the accumulation of surrounding material over millions of years rather than from the collapse of a single star.
