Astronomers, analyzing data from the European Gaia space telescope, have discovered two black holes closest to the Earth, named Gaia BH1 and Gaia BH2.
The first black hole is located in the Ophiuchus constellation, 1560 light-years away from Earth, the second one is found in the Centaurus constellation, 3800 light-years away.
Both objects are unique. It was possible to detect them by studying the characteristics of the movement of companion stars revolving around them: the strange fluctuations have shown that these stars revolve around some massive objects; in both cases their mass was about ten times that of the Sun. Those objects did not emit light, which made scientists think that they obviously are black holes.
Until recently, all black holes known to astronomers were detected by emitting light, usually in the X-ray and radio ranges; light is produced by the matter absorbed by the object. However, it turns out that Gaia BH1 and Gaia BH2 are indeed black holes, and were detected solely through gravitational effects.
The orbits of the stars orbiting these black holes are unusually high, which makes them different from the so-called X-ray binaries with low star orbits around the black hole. This has given scientists reason to believe that new types of binary systems may arise relatively often.
The European Space Agency also notes that the Gaia space telescope has proven to be a suitable tool for detecting such objects; it precisely measures the position and motion of billions of stars, providing important information about the objects that have a gravitational influence on these stars.
Earlier, specialists working with the American Chandra X-ray Observatory and the MeerKAT radio telescope located in South Africa tried to detect traces of Gaia BH2 in the X-ray and radio ranges. In both cases nothing was found.