Astronomers have found a star orbiting a black hole twice in an hour
Astronomers have found evidence of a star orbiting a black hole twice an hour. This is the tightest orbital dance ever seen by a black hole and a companion star in our Milky Way galaxy. This discovery was made using the Chandra X-ray Observatory and NuSTAR, two of the best NASA’s space-based telescopes.
The stellar couple which is often known as a binary located in the globular cluster 47 Tucanae, which is a dense cluster of stars in out galaxy located 148000 light years away from Earth.
Back in 2015 a research team lead by Curtin University and the International Centre for Radio Astronomy Research found that the stellar couple made with a black hole. The recent study reveal that the system known as X9 consistently changes in X-ray brightness for every 28 minutes, which is likely the length of time it takes the companion star to make one complete orbit around the black hole.
But the evidence of huge amounts of oxygen in the system points that the X9 contains a white dwarf star orbiting a black hole at just 2.5 times the separation between the Earth and the Moon. Dr Arash Bahramian, from the University of Alberta in Canada said:
“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,”
Well we all wonder that how a black hole get such a close companion? There is one possibility, when the black hole smashed into a red giant star and as gas form. The out region of the star were ejected a binary was form, which contain a black hole and a white dwarf. Then orbit of binary have shrunk as gravitational waves were emitted until the black hole start pulling material from dwarf. It is possible that space-based gravity wave observatories in the future could be sensitive enough to detect.