Scientists have discovered a black hole in the Milky Way so huge that it challenges existing models of how stars evolve, researchers said Thursday.
LB-1 is 15,000 light years from Earth and has a mass 70 times greater than the Sun, according to the journal Nature.
The Milky Way is estimated to contain 100 million stellar black holes but LB-1 is twice as massive as anything scientists thought possible, said Liu Jifeng, a National Astronomical Observatory of China professor who led the research.
“Black holes of such mass should not even exist in our galaxy, according to most of the current models of stellar evolution,” Professor Liu Jifeng “We thought that very massive stars with the chemical composition typical of our galaxy must shed most of their gas in powerful stellar winds, as they approach the end of their life. Therefore, they should not leave behind such a massive remnant. LB-1 is twice as massive as what we thought possible. Now theorists will have to take up the challenge of explaining its formation.”
Follow-up observations from Spain’s Gran Telescopio Canarias and the Keck I telescope in the United States allowed them to precisely characterize the system. The star orbits the black hole every 79 days.
A similar-sized black hole was the end product of the first detected emission of gravitational waves. While the mass of LB-1 might be explained away with a (maybe multiple) merger scenario, the presence of the star certainly complicates the explanation.
“This discovery forces us to re-examine our models of how stellar-mass black holes form,” said LIGO Director Professor David Reitze from the University of Florida. “This remarkable result along with the LIGO-Virgo detections of binary black hole collisions during the past four years really points towards a renaissance in our understanding of black hole astrophysics.”