(ORDO NEWS) — The black hole Gaia BH1 was the closest to the Earth of all known. It is only 1600 light years away and has ten times the mass of the Sun.
It is hypothesized that there may be hundreds of millions of stellar-mass black holes in the Milky Way. Detecting such compact and dark objects is extremely difficult, and so far only a few dozen are known.
The overwhelming majority of the found black holes were “given away” by their partner, a neighboring star, from which the hole draws matter. Twisting and accelerating, this substance is very hot and actively emits X-rays.
Black holes that are not part of such X-ray binary systems are much more difficult to notice. Such an opportunity is provided, for example, by gravitational lensing the distortion of the light of distant stars, which, on its way to us, passes close to a heavy and dense black hole.
However, only candidates for such objects have been found so far, and none of them has been conclusively confirmed.
Finally, an indication of the presence of a black hole can give a slight fluctuation in the position of a neighboring star, with which it rotates around a common center of gravity.
Such a find was made a couple of years ago when scientists reported the discovery of a potential black hole in the HR 6819 system, just 1,100 light-years from the Sun. However, later this discovery was not confirmed.
The Gaia space telescope has noticed the oscillations of a solar-type star located 1560 light-years away. This movement may be caused by an invisible massive object, so astronomers further examined the star with ground-based instruments at the Gemini Observatory.
The work made it possible to refine the parameters of the star’s motion, to calculate its mass and the mass of its invisible partner.
The black hole Gaia BH1 is estimated at 10 solar masses, and a solar-type star revolves around it. They are separated by approximately the same distance as the Earth from the Sun.
“Take the solar system, put a black hole in the place of the Sun, the Sun in the place of the Earth, and you get this system,” explains Kareem El-Badry, one of the authors of the find. “This is the first reliable detection of a solar-type star in a wide orbit around a stellar-mass black hole.”
Gaia BH1 is 1,560 light-years away, about half the distance from our closest known black hole. But it is possible that closer ones will be found in the future.
In a few years, the Gaia telescope will complete another survey of the sky with ultra-precise data on the positions and speeds of billions of stars. These observations may provide clues to other black holes that are nearly invisible by other methods.
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