United States astronomers have discovered the biggest black hole orbiting a star 1,8-million light-years from Earth in the constellation Cassiopeia, with a record-setting mass of 24 to 33 times that of our Sun, Nasa said on Tuesday.
The massive newcomer beats the previous stellar-mass black hole discovered on October 17 in the M33 galaxy that has 16 times the mass of our Sun, the US space agency said.
Like the much larger, supermassive black holes found at galaxy centres, stellar-mass black holes have such powerful gravity fields that not even light can escape them. Astronomers estimate their mass by measuring their gas emissions and the gravitational effect on the stars they orbit.
”We weren’t expecting to find a stellar-mass black hole this massive,” says Andrea Prestwich of the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts.
Lead author of the discovery paper in the November 1 Astrophysical Journal Letters, Prestwich and his team found the new stellar-mass black hole using Nasa’s Chandra X-ray Observatory.
”We now know that black holes that form from dying stars can be much larger than we had realised,” he added.
Prestwich’s team was able to measure the black hole’s mass because it has an orbiting companion: a hot, highly evolved star. The star is ejecting gas in the form of a wind.
Some of this material spirals toward the black hole, heats up, and gives off powerful X-rays before crossing the point of no return. – AFP
