Despite the harsh conditions that exist around black holes located in the center of the Milky Way, new research shows that even in such an aggressive environment, new stars and planets can form. The possibility of this is confirmed by the detected celestial bodies, which are located only a few light years from black holes.
Discovered more than 10 years ago, bright and supermassive stars, whose weight is more than 4 million times the mass of the Sun, caused violent controversy in the astronomical community. Are they absorbed by black holes after they form? How do they manage to stay in their orbits?
Most astronomers reject the idea of forming stars near black holes, as the latter cause significant damage to the surrounding space, distorting it and absorbing all nearby objects. However, new studies of small stars in the center of the galaxy suggest the opposite. Namely, a considerable number of “adult” stars were formed not far from black holes.
“New evidence of ongoing star formation near black holes is the“ nail in the coffin ”of the theory that stars are formed solely statically in one place,” said senior researcher Farhad Yusuf-Zade, of Northwestern University. "Observations, if confirmed, will indicate a low probability that stars can migrate from other places in the galaxy," the researchers said. Stars are born in clouds of dust and gas. Turbulence inside these clouds creates clusters and knots that begin to collapse under their own weight. The clusters are heated and compacted, turning into protostars. The latter received this name due to the fact that thermonuclear synthesis of hydrogen into helium had not yet begun.
Protostars are often very difficult to discern. This object still does not generate enough visible light, due to what is happening inside the nuclear fusion. The latter, in turn, may still be hidden by a gas disk and dust accumulations around it.
It was for this reason, Farhad Yusuf-Zade and his colleagues, who used the Very Large Array radio telescope in New Mexico to scan the sky, did not find anything near black holes. Scientists have fixed only gas and dust disks around holes and not a single protostar.
“You yourself can see these beautiful“ comet-like ”structures,” said Yusuf-Zadeh in an interview with Space.com. Intense luminescence can be observed both from previously discovered stars and clusters, and from those that were first discovered, such as, for example, star clusters of the Orion Nebula.
“There remains, of course, one big question, namely, how stars are formed in the immediate vicinity of the black hole and how to avoid the negative impact of these giants in the neighborhood,” Yusuf-Zadeh noted. “Many scientists argue that the formation of a star near a black hole is ruled out. However, nature refutes these claims. ”
Astronomers figured out how to solve this mystery. Over the past decade, they have developed two scenarios, both of which are tested on a nearby black hole, to simulate the process of star formation. In the first case, gas and dust accumulations can fall apart in the strong gravitational field of a black hole and form into the disk surrounding it. It is in this disk that the young stars will form, and the same disks around the stars will become the basis for the appearance of the planets. This scenario was first proposed in 2005 by Sergei Nyashkin, an astronomer from the University of Leicester in the UK, and was an explanation of the formation of low-mass stars.
The second scenario involves stretching the gas cloud into a long narrow ribbon, which is affected by two opposing gravitational forces from a black hole, keeping this ribbon near you. In this tape and the formation occurs and the forced existence of stars and planets.
Both scenarios are designed to explain the formation of stars near a black hole called Sagittarius A.
However, some scientists do not rush to conclusions.
“The center of our galaxy is a unique and extreme place, radically different from our solar system,” said Jessica Lou, an astronomer at the University of Hawaii Astronomy. "Therefore, it is important that astronomers do not rush to their conclusions."
“Similar gas clusters, with a similar shape for protostars, were observed in the cluster adjacent to the Orion Nebula, there are other places with similar, small gas clots that do not border on black holes,” Lu cautioned in response to a question from Space.com.
Previously, it was believed that even small stars formed within a few light years. The surprise is the possible fact of the formation of stars in extremely adverse conditions over many light years in the vicinity of black holes. As a rule, a disk around a protostar breaks up into clots of gas and dust, which are subsequently compacted into future planets. But in the extreme conditions of the neighborhood with a black hole, the effects of stellar winds, the “lion” part of the mass of these disks is lost. Yusuf-Zadeh and his colleagues believe that, despite the unfavorable environment, a sufficient amount of material remains around the protostar for the formation of planets.
The team of scientists is planning to use the Atakam high-millimeter / submillimeter grid radio telescope in the north of Chile in a further study of the formation of planets and stars. The high sensitivity of these telescopes will help to cover a larger space with potential protostars and gas clusters.
"We are only now starting to really explore this area," Yusuf-Zadeh said, adding that the search for questions about the formation of stars in the vicinity of black holes will continue in the future.
The results and comments on the studies of the formation of stars near black holes will be published in the next issue of The Astrophysical Journal Letters, and are also available online.