Recently, astronomers have discovered evidence indicating the presence of a rare intermediate-mass black hole within the Omega Centauri, the largest globular star cluster in the Milky Way visible to the naked eye on Earth. This black hole is estimated to have a mass at least 8,200 times that of the Sun. If confirmed, it would be the closest black hole to Earth known to date.
According to a report on the NASA website on July 10, most known black holes are either extremely massive or relatively light. Intermediate-mass black holes are elusive and considered a missing link in the evolution of black holes.
A team of international astronomers, using over 500 images captured by NASA’s Hubble Space Telescope, identified seven rapidly moving stars in the innermost region of Omega Centauri. These stars provided compelling evidence of the presence of an intermediate-mass black hole within the star cluster exerting gravitational pull on them.
Omega Centauri is composed of approximately 10 million stars bound by gravity. The mass of this star cluster is about ten times that of other large globular clusters, nearly as massive as a small galaxy.
Maximilian Häberle, a Ph.D. student in astronomy at the Max Planck Institute for Astronomy in Germany, who led the study, said, “We have discovered seven stars that shouldn’t be there.” He explained, “They are moving so fast that they would escape the cluster and never return. The most plausible explanation is that a very massive object is forcefully pulling these stars towards the center, and the only thing large enough is a black hole with a mass at least 8,200 times that of the Sun.”
Nadine Neumayer, another member of the research team from the Max Planck Institute for Astronomy, added, “This finding represents the most direct evidence so far of an intermediate-mass black hole within Omega Centauri.” She stated, “It is exciting because very few black holes with similar masses are known. Within our neighboring universe, the black hole in Omega Centauri could be the best example of an intermediate-mass black hole.”
If confirmed, this black hole, located 17,700 light-years away from Earth, would be closer to our planet than the supermassive black hole at the center of the Milky Way, which is 26,000 light-years away and has a mass 4.3 million times that of the Sun.
The results of the study were published in the journal Nature on July 10.