A new discovery made by astronomers has revealed the existence of a star that is orbiting two times in an hour around a black hole at a distance, which is just two and a half times that of the Earth and moon.
This is the first time a star has been found lingering in such close proximity to a black hole.
Astronomers led by the Michigan State University and the University of Alberta, with the help of some telescopes — namely NASA's NuSTAR and the Chandra X-Ray Observatory, as well as the Australia Telescope Compact Array — chanced upon the exciting discovery.
Using the telescopes on the ground, the astronomers were able to perceive the fluctuations in X-ray in the white dwarf/black hole binary system, which is called the X9. The X9 is located in a thick cluster of stars, which is located nearly 14,800 light-years from our planet in a galaxy called Tucanae.
Even though astronomers have known about the binary for several years, it was only in 2015 that the team of scientists from Curtin University and the International Centre for Radio Astronomy Research found that it was possibly composed of materials being pulled by the black hole from another companion star.
The Binary System: X9
Known as the X9, the binary system has a constant fluctuation in brightness nearly every 28 minutes. This span is almost equal to the time taken by a star to orbit the black hole once. The X9 contains massive oxygen amounts based on evidence, which suggests that it houses a white dwarf star.
This dwarf star apparently orbits the black hole at a really close distance. Initially, the astronomers thought that the X9 was a pair of stars orbiting the Earth. However, with the help of radio observations from ATCA in 2015, the astronomers were able to realize that one of the objects is like a black hole ripping material from a white dwarf star.
"This white dwarf is so close to the black hole that material is being pulled away from the star and dumped onto a disk of matter around the black hole before falling in," says Arash Bahramian, the study's lead author.
How Did The Black Hole Get Such A Close Companion Star?
Black holes are notorious for consuming stars by tearing them apart through the application of unequal and strong gravitational forces. However, the white dwarf star in the X9 seems to have escaped this ordeal and is safe, at least for now.
One of the reasons for the black hole getting a companion in such proximity could be that the former may have had a huge collision with a massive red star. This may have led to the release of the gas from the external region of the star, resulting in the formation of a binary. This binary contained both the black hole and the dwarf star.
The research has been published in the Royal Astronomical Society.
Here is the video showing the details about the X9.