Listen: Understanding the Black Hole Binary AO620-00
"A unicorn follows Orion across the sky Manasseh, which is to the lower left of Orion at nightfall. It's not much to look at though it's brightest stars are so faint that you need pretty dark skies to pick them out. Perhaps it's fitting then that one of its most interesting denizens is a black hole the closest one to earth. Eo six twenty minus oh is more than three thousand light years away. The black hole produces no energy. But it has a companion a normal star about half as massive as the sun, and it's the interactions between these two objects that reveals the black holes presence for one thing over the last century or so a oh six twenty has flared up twice the second of those events was observed by an x Ray telescope in space, it found that the systems x Ray brightness jumped to a hundred thousand times its normal level. The outburst may have. Been produced by gas that the black hole stole from its companion. The black hole takes gas from the star. All the time. Forming a disc around the black hole as the gas. Piles up though, it may become unstable lots of gas may plunge toward the black hole in a rush heating to millions of degrees and shining brightly just before it vanishes measuring the orbit of the visible star. And it's dark companion suggests that the black hole is about six times the mass of the sun a small black hole. That's a fairly close."