Largest Stellar Black Hole in our Galaxy is Unintentionally Discovered by Scientists

A paper published in Astronomy & Astrophysics state that by chance, astronomers have found the largest star black hole yet discovered in the Milky Way galaxy.

Sagittarius A*, the supermassive black hole at the center of the Milky Way, is significantly larger than a stellar black hole, which is created when a star collapses, usually following a supernova explosion. While “Gaia BH3” has a mass 33 times that of the sun, its mass is four million times that of the sun.

Surprising Discovery

Gaia BH3, the second-closest known black hole to Earth, is located in the constellation Aquila, 2,000 light-years distant. Most have a mass ten times that of the sun. Cygnus X-1, the second largest black hole in the galaxy, is only 21 solar masses in mass.

As far as the Observatoire de Paris, a component of France’s National Centre for Scientific Research (CNRS) and a member of the Gaia project, is concerned, “No one was expecting to find a high-mass black hole lurking nearby, undetected so far,” stated Pasquale Panuzzo. “This is the kind of discovery you make once in your research life.”

Associated Star

The discovery was made in data obtained from the Gaia mission of the European Space Agency during the preparation of a large-scale data release to the scientific community in 2025.

Because the black hole affects the partner star’s orbit, Gaia was able to identify it. Using data from the Very Large Telescope of the European Southern Observatory in the Atacama Desert of Chile, the observations were verified twice.

Metal-Deficient Star

Given that “metal” is an acronym for atoms heavier than hydrogen and helium in astronomy, the discovery of such a huge black hole shows that black holes can develop from the collapse of metal-poor stars, which contain less components heavier than hydrogen and helium. The extremely low metal content of BH3’s companion star raises the possibility that the black hole was formed by a metal-poor collapse of the parent star.

It is believed that these stars leave behind more material to become high-mass black holes after they die because they lose less mass during their lifetimes.

In order to enable other astronomers to start examining this remarkable black hole right away and maybe learn whether it is attracting matter from its surroundings, the study’s authors decided to disclose their results ahead of schedule.