An international team of scientists has discovered a stellar black hole in Earth's “cosmic backyard” containing the mass of 70 suns.
It's a black hole that forms after stars die, collapse, and explode. Researchers had long believed that the size limit was only 20 times the mass of our sun because as these stars die, they lose most of their mass through explosions that force matter and gas swept away by stellar winds.
This theory has now been toppled by LB-1, the newly discovered black hole. Located about 15,000 light years away, it has a mass 70 times greater than our sun, according to a press release from the Chinese Academy of Sciences.
“Black holes of such mass should not even exist in our galaxy (星系), according to most of the present models of stellar evolution,” said Liu Jifeng, head of the team that made the discovery.
“LB-1 is twice as massive as what we thought possible. Now theorists will have to take up the challenge of explaining its formation.”
Scientists are now scratching their heads at how LB-1 got so huge.
The team has proposed some theories. LB-1's sheer size suggests that it “was not formed from the collapse of only one star,” the study said — instead, it could potentially be two smaller black holes orbiting each other.
Another possibility is that it formed from “fallback supernova (超行星).” This is when a supernova — the last stage of an exploding star — ejects (喷射) material during the explosion, which then falls back into the supernova, creating a black hole. This fallback formation is theoretically possible, but scientists have never been able to prove or observe it.
There are several types of black holes and stellar black holes like LB-1 are on the smaller side, according to NASA. Supermassive black holes are much bigger — they can be billions of times the mass of our sun.
Scientists believe supermassive black holes may have connection with the formation of galaxies, as they often exist at the center of the mass star stems but it is still not clear exactly how, or which form first.
