Scientists do not yet know exactly how this cosmic duet appeared and how long their connection lasts.
The researchers found a white dwarf star (dim and dense, which has already burned most of its hydrogen and helium) just 600,000 miles from a suspicious black hole. And this is the closest orbit ever discovered.
The dual system 47 Tukan X9, remote from the Earth at 14,800 light years, has been under the scrutiny of scientists for some time.
Initially, astronomers believed that the system consists of a solar star orbiting a white dwarf. These objects have about the same mass as Sun, but are compressed to half the Earth's diameter.
But in 2015, observations in radio telescopes showed that the white dwarf X9 was actually in orbit of a small black hole.
Black holes are so dense objects that even photons of light cannot escape from gravitational attraction. They are detected through control radiation emitted by the material they consume from nearby stars and gas.
However, the detection of X9 was non-standard, since black holes did not occur in such globular star clusters.
The latest study showed that the white dwarf X9 revolves around its “companion” approximately every 28 minutes, moving away by 600,000 miles. This exaggerates 2.5 times the distance between the Moon and Earth. While the system seems stable. Scientists do not know whether a black hole, which takes away material from a rotating white dwarf, will lead to an explosion of a star.
“The white dwarf is located so close that the material is torn off and dumped onto the mother’s disk around the black hole, before being inside,” said astrophysicist Arash Bahramian from the University of Albert in Canada. “However, we do not think that the star will be in oblivion and most likely will remain in orbit.”
If the white dwarf continues to lose weight, it can evolve into an exotic type of planet or completely evaporate.
Scientists also do not know exactly how this pair was formed.
According to one of the options - a black hole collided with a red giant star, because of which the outer regions of the star were removed. The remaining nucleus became a white dwarf and settled in the hole's orbit.
According to another version, X9 actually revolves around a neutron star, and not a black hole. In a neutron star, speed is faster as it takes material from the dwarf. Scientists have already found several such objects - transient millisecond pulsars. But the X-ray and X-ray radiations are slightly different.
The discovery made by the NASA Chandra X-ray Observatory, NASA's NuSTAR telescope and Australia Telescope Compact Array.