Research by astronomers shows that super-massive black holes are not entirely destructive forces in the universe. Scientists have found evidence that they also create conditions that support the formation of new stars.
Black holes are the evolutionary endpoints of huge, energetic stars that have collapsed on themselves. The gravitational pull is so great, any cosmic body near a black hole is sucked into it. Even light cannot escape the inward force.
So, scientists were surprised to discover a cluster of stars hovering near a black hole in the middle of our galaxy, the Milky Way. The question is, why were they there?
Using NASA's Chandra X-ray telescope, which is able see through the shroud of dust and gas near black holes, astronomers have developed two theories.
One theory is that the stars had been formed elsewhere and were, in fact, being slowly sucked into Milky Way's black hole. If this were the case, these stars would be small and too numerous to count. To find out, scientists compared the stars near the black hole to stars in another part of the galaxy, and the stars surrounding the black hole proved to be 10 times bigger.
A second theory put forth by astronomers, including Sergei Nayakshin of the University of Leicester in England, is that somehow the massive stars formed in spite of the black hole. He says the accretion disk, a swirling mass of dust and gas at the mouth of black holes that helps feed them, is mostly inhospitable. "But farther out the disc is too cold and too massive, and so some disk regions actually collapse to form stars," he said.
Mr. Nayakshin believes the stars remain at the edge of their black hole until they, too, become unstable in hundreds of millions of years and implode. At that point, they may be sucked up by the black hole that spawned them, or meld with other nearby black holes.
NASA's Chandra program scientist Kim Weaver says it's clear that black holes are not purely destructive. "They can also be creative and nurturing forces, offering an environment that provides a place for stars to form. The accretion disk can actually be a cradle for star birth. This result suggests that black holes have a Jekyll and Hyde nature," he said.
The finding by Sergei Nayakshin and colleagues will be published in the journal Monthly Notices of the Royal Astronomical Society.