The black hole has 12 times the mass of the Sun and is located only 1,550 light-years away.
The discovery of a monstrous stellar black hole , which is about 12 times the mass of the sun and located 1,550 light-years away, is reported in the Astrophysical Journal .
“It is closer to the sun than any other known black hole , at a distance of 1,550 light-years,” says Sukanya Chakrabarti, a professor of physics at the University of Alabama at Huntsville (UAH) and lead author of the study. “So, it’s practically in our backyard.”
Black holes are considered exotic because, although their gravitational pull is clearly felt by stars and other nearby objects, no light can escape from a black hole, so they cannot be seen in the same way as visible stars.
“In some cases, such as in the case of supermassive black holes at the centers of galaxies, they can drive galaxy formation and evolution,” says Chakrabarti in a statement. “It is not yet clear how these non-interacting black holes affect the galactic dynamics in the Milky Way. If they are numerous, they can affect the formation of our galaxy and its internal dynamics.”
To find the black hole, Chakrabarti and a team of US scientists analyzed data from nearly 200,000 binary stars released over the summer by the European Space Agency’s Gaia satellite mission.
“We looked for objects that were reported to have large companion masses but whose brightness could be attributed to a single visible star,” he says. “So you have a good reason to think the partner is dark.”
Interesting sources were followed up with spectrographic measurements from various telescopes, including the Automatic Planet Finder in California, the Giant Magellan Telescope in Chile, and the WM Keck Observatory in Hawaii.
“The pull of the black hole on the visible Sun-like star can be determined from these spectroscopic measurements, which give us a line-of-sight velocity due to a Doppler shift,” says Chakrabarti. A Doppler shift is the change in the frequency of a wave relative to an observer, much like the pitch of a siren’s sound changes when an emergency vehicle passes.
“By looking at the line-of-sight velocities of the visible star — and this visible star is similar to our own sun — we can infer how massive the black hole’s companion is, as well as the period of rotation and how eccentric the star is. orbit,” she says. “These spectroscopic measurements independently confirmed the Gaia solution which also indicated that this binary system is composed of a visible star orbiting a very massive object.”
An endless search
The black hole must be deduced from the analysis of the motions of the visible star because it does not interact with the luminous star. Non -interacting black holes typically don’t have a donut-shaped ring of accumulating dust and accompanying material that they interact with another object. The accumulation makes the interacting type relatively easier to observe optically, which is why many more of that type have been found.
“Most black holes in binary systems are in X-ray binaries; in other words, they are bright in X-rays due to some interaction with the black hole, often due to the black hole gobbling up the other star . Chakrabarti says. “As things from the other star fall into this deep well of gravitational potential, we can see the X-rays.”
These interacting systems tend to be in short period orbits. “In this case, we’re looking at a monster black hole, but it’s in a long-period orbit of 185 days, or about half a year. It’s quite far from the visible star and not moving toward it,” he explains.
The techniques the scientists used should also be applied to find other non-interacting systems. “This is a new population that we’re just beginning to learn about and it will tell us about the formation channel of black holes, so it’s been very exciting to work on this,” says Peter Craig, PhD candidate at the Institute of Rochester of Technology who is advised on his thesis by Chakrabarti.
“Simple estimates suggest that there are about a million visible stars that have companion massive black holes in our galaxy,” says Chakrabarti. “But there are a hundred billion stars in our galaxy, so it’s like looking for a needle in a haystack. The Gaia mission, with its incredibly precise measurements, made it easier by narrowing down our search.”
Scientists are trying to understand the formation pathways of non-interacting black holes . “Currently, theorists have proposed several different pathways, but non-interacting black holes around luminous stars are a very new type of population,” says Chakrabarti. “So it will likely take us some time to understand their demographics, how they form, and how these channels are different from, or similar to, the better-known population of interacting and merging black holes.” (EuropePress)