Science: In theory, all you need is a large mass in a small space to form a black hole. A large mass in a small space will inevitably collapse to form a black hole. It will be forced to collapse by its own gravity. But usually we think of something triggering that collapse. For example, the star runs out of fuel and explodes as a supernova, crushing the star inward, sparking the collapse, until gravity takes control and does the rest.
In the real space of our galaxy, astronomers have observed stellar-mass black holes — say, objects five to 50 times the mass of our sun — in double systems. It’s possible to see them in double systems because the presence of the second star means astronomers can see the hole’s effect on the star, often in the form of an accretion disk swirling around the hole. Now, for the first time, astronomers have confirmed a black hole in a triple star system. They say this is evidence that no supernova occurred in this system, but instead the black hole was formed directly from the collapse.
