Scientists discovered the black hole from the way it interacts with two stars – one that orbits the hole, and the other that orbits this inner pair. It’s about 1,000 light-years away, or roughly 9.5 thousand, million, million km, in the Constellation Telescopium. Normally, black holes are discovered from the way they interact violently with an accreting disc of gas and dust. As they shred this material, copious X-rays are emitted. It’s this high-energy signal that telescopes detect, not the black hole itself.
So this is an unusual case, in that it’s the motions of the stars, together known as HR 6819, that have given the game away.
Mr. Dietrich Baade, Emeritus Astronomer at the European Southern Observatory (ESO) organization in Garching, Germany said that it may be the first such case where a black hole has been found this way and it’s also the most nearby of all black holes, including the accreting ones.
Scientists had begun the study of HR 6819 many years ago when looking for what’s termed to be star. This is a star that rotates so rapidly that it nearly tears itself apart, and the outer object in this pairing is a good example. Studies using the 2.2m telescope at La Silla Observatory in Chile reveal the inner of the two visible stars to be orbiting an unseen object every 40 days.Presumed to be a black hole, this object has a likely mass of at least four times that of our Sun.
Astronomers have spotted only a couple of dozen black holes in our Milky Way Galaxy to date, nearly all of which strongly interact with their accretion discs. But statistics tell there must be many, many more out there. The astronauts told there should be about 100 million black holes in Milky Way. So there should be perhaps a couple more that are closer by.