Scientists estimate that in the Milky Way Galaxy, there are about 100 million black holes. Scientists generally accept that black holes in our Galaxy could be no more than 20 times the mass of the Sun. A new discovery by a group of scientists led by a Chinese team has challenged that notion.
The team has spotted a black hole that is 70 times the mass of the Sun. LB-1, as the massive black hole is called, is about 15 light-years away from Earth. Discovery of the giant black hole was a surprise according to one of the scientists on the team as current models of stellar evolution say that black holes of this size shouldn’t exist.
Scientists thought before the discovery of the new black hole that very massive stars with the chemical composition found in our Galaxy would shed most of their gas in powerful stellar winds as their end of life approached. The discovery of LB-1 means that a black hole twice the mass of what the team thought was possible exists, and theorists will take up the challenge of explaining its formation.
The discovery of black holes was only possible when the black hole gobbled up gas from a companion star until a few years ago. Gobbling gas from a companion star created X-ray emissions that were detectable from Earth. Since most black holes aren’t actively consuming gas from a nearby star, only about two dozen Galactic stellar black holes have been identified and measured.
The Chinese team was able to counter that limitation by using the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to look for stars that orbit an invisible object pulled by its gravity. After the initial discovery of LB-1, other observations showed that LB-1 was a 70-solar mass black hole that had a star eight times heavier than the Sun orbiting it every 79 days.