A star on the verge of exploding is an exceedingly useful thing. Identify it through a telescope and you can examine its telltale behavior before and after the event, in the process learning whether our existing theories about neutron star and black hole formation are supported by observation. We’ve seen stars on the order of twenty solar masses go into supernova mode, their internal elements becoming heavier and heavier through the progress of nuclear fusion.
Iron is the result, but at stellar center the iron breaks down into protons and neutrons, causing an internal collapse and a supernova flash that causes the star’s outer layers to be blasted into space. The core, meanwhile, mutates into a neutron star, its radius reduced to a matter of ten or so kilometers. All of this occurs more or less as theory describes, but until recently, we hadn’t had the chance to study a larger 50 solar mass star in its supernova agonies. A black hole should result.
Avishay Gal-Yam (Weizmann Institute Faculty of Physics) and Douglas Leonard (San Diego State) located a star possibly twice that size, watching as its mass collapsed in on itself to form a black hole. This Weizman Institute news release reveals that only a small part of the star’s mass was blown into the stellar neighborhood. Most of it was drawn into the collapsing core.
Subsequent telescope images show that the star has, for all intents and purposes, vanished from view, a black hole that light cannot escape. The notion that stars with masses from tens to hundreds of times larger than our Sun all end up as black holes thus receives dramatic confirmation.