The conventional wisdom among astronomers is that black holes – those exceptionally dense objects whose gravity is so powerful that even light cannot escape – form in the violent explosion of a massive dying star, called a supernova. But it turns out that some may be born with a benign form.
Researchers have identified a black hole that appears to have arisen from the collapse of a massive star’s core as it dies, but without the usual explosion. It was seen gravitationally bound to two ordinary stars.
Black holes have previously been observed orbiting either another star or another black hole in what is called a binary system. But it is the first known example of a triple system containing a black hole and two stars.
This system is located in the Cygnus constellation, about 7,800 light years from Earth. A light year is the distance that light travels in one year, 5.9 trillion miles (9.5 trillion km).
This black hole, named V404 Cygni, has been studied extensively since it was confirmed in 1992. It was previously thought to be orbiting only one other star, but data from the European Space Agency’s Gaia space observatory has revealed that it has two companions.
The black hole, which has about nine times the mass of our Sun, is in the process of eating one of its companions, a star about seven-tenths as massive as the Sun, the researchers said. That star orbits the black hole every 6-1/2 days at a distance only one-seventh the distance separating Earth and the Sun.
The black hole appears to be removing material from the star, called the red giant phase, as part of its natural aging process.
Researchers discovered a star about 1.2 times the mass of the Sun, which is gravitationally bound to both of them, but also very distant, orbiting them every 70,000 years at a distance 3,500 times the distance that separates Earth and the Sun. Is.
The reason researchers suspect a benign birth process for black holes is simple. He said, if the star that became a black hole had exploded, the triple system would have broken up.
A black hole is thought to form when a massive star exhausts the nuclear fuel in its core and collapses inward due to its gravitational pull, causing a massive explosion that ejects its outer layers into space. Blows in. The resulting crushed core forms a black hole.
But some astronomers have proposed another path for black hole formation called “direct collapse” in which the star collapses into a cavern after expending all its fuel but does not explode.
“We call these events ‘failed supernovae’.” Basically, gravitational collapse acts too quickly to be able to trigger a supernova and you get an explosion instead – which sounds super dramatic and awesome but it’s ‘benign’ in the sense that you don’t get any. “Do not eject matter,” said astronomer Kevin Burge of the Massachusetts Institute of Technology, lead author of the study published in the journal Nature.
Researchers estimate that the members of this triple system first formed as normal stars about 4 billion years ago.
“The triple system could not have survived if the black hole had been born with a natal kick,” said the Caltech astronomer, “so this discovery tells us that at least some black holes form without a kick — that is, an explosive supernova.” Instead of indicating a quiet explosion.” Karim Al-Badri, co-author of the study.
This system will not have three members forever, given that the black hole is swallowing its nearest neighbor. This suggests that some known binary systems with a black hole and an ordinary star may have originally formed as a triple system, but the black hole may have swallowed one of its companions.
“People have actually predicted that black hole binaries might form mostly through triple evolution, but there was no direct evidence of that until now,” El-Badry said.
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