Black hole of record mass discovered in the Milky Way

33 times the mass of the Sun

April 16, 2024 12:24 p.m. Robert Klatt

A stellar black hole has been discovered in the Milky Way and has a significantly greater solar mass than astronomy previously thought possible.

Garching (Germany). Supermassive black holes, like the bright quasar TON 618, often have masses of several million solar masses. Stellar black holes, resulting from the collapse of stars, almost always only have a mass of several solar masses. Astronomers estimate that there are around 100 million stellar black holes in the Milky Way. Since most of them do not heat the material, they are difficult to detect. Furthermore, it was previously assumed that black holes in Earth’s galaxy could have a maximum of 20 solar masses due to their composition.

Researcher of European Southern Observatory (ESO) discovered the most massive stellar black hole in the Milky Way by analyzing data from ESA’s Gaia space telescope. The black hole BH3 has a mass of 33 solar masses and is only 2,000 light years from Earth.

Free-falling star reveals black hole

According to the publication in the specialist magazine Astronomy and Astrophysics Astronomers discovered the black hole because they discovered unusual wobble movements of a star in space telescope observation data. They then took a closer look at the space area using different telescopes and discovered that the black hole’s companion star BH3 contains virtually no elements heavier than hydrogen and helium. The star is therefore considered to be poor in metal.

This observation is consistent with the theory of stellar black holes, which suggests that these stars lose less mass before collapsing into black holes. Since two stars orbiting each other are usually very similar, astronomers assume that the BH3 black hole was also previously a metal-poor star.

BH3 black hole near Earth

Located 2,000 light years away, the BH3 black hole is one of the closest known black holes to Earth. The previously known record holder BH1 is significantly closer to Earth, at a distance of 1,500 light years. Evidence has also been discovered that the Hyades star cluster contains several stellar black holes located just 150 light years away. However, these have not yet been confirmed.

Astronomy and astrophysics, doi: 10.1051/0004-6361/202449763