Science and Technology Daily, Beijing, April 17 (Reporter) — Astronomers at the European Southern Observatory have identified the most massive stellar black hole in the Milky Way discovered to date. This black hole was found in data from the European Space Agency's Gaia mission. The black hole, named Gaia BH3, has a mass 33 times that of the Sun. The related paper was published on the 16th in the journal Astronomy & Astrophysics.

Stellar black holes are formed by the collapse of massive stars. Previously discovered black holes in the Milky Way have an average mass of about 10 times that of the Sun. Even Cygnus X-1, the second most massive stellar black hole known in the Milky Way, has only 21 solar masses.

It is noteworthy that this black hole is very close to Earth, only 2,000 light-years away. It is located in Aquila and is the second-closest known black hole to Earth.

Astronomers have discovered similar massive black holes outside the Milky Way and speculate that they may have formed from stellar collapse, with a chemical composition containing almost no elements heavier than hydrogen and helium. Astronomers believe that these so-called metal-poor stars lose less mass during their lifetimes, and therefore leave behind more material after they die, thereby producing high-mass black holes. However, direct evidence linking metal-poor stars to massive black holes has so far been lacking.

Paired stars often have similar compositions, which means that Gaia BH3's companion star holds important clues about the special stellar black hole formed by collapse. The data show that Gaia BH3's companion is a metal-poor star, indicating that the star that collapsed to form Gaia BH3 was also a metal-poor star, consistent with predictions.