Black Hole Stars are only theoretical objects, so take everything said here with a grain of Sodium Chloride. I will be referring to them as though they did exist though, to make things less complicated.
Black Hole Stars are also called Quasi-Stars. They are theorized to have been stars that formed in the very early universe, with matter being so dense they could grow incredibly large without any fusion-ignition blowing it away. They would grow so fast that their cores collapsed into Black Holes while they were still forming. The Black Hole would be fed by the massive star’s gravity pushing gas in, while the star was kept steady by the radiation-pressure produced by the Black Hole. This created a Black Hole that could grow for millions of years (supposedly), gaining enough mass to become Supermassive or Ultramassive. Then, the accretion disk would get too big and would shear the star in two. Although this wasn’t quite a supernova, it was a lot more violent than one, with the star getting gutted, ripped apart, and the remains getting ejected into space.
These stars were theorized by scientists to try and solve a question. That question refers to the massive size gap in Black Holes. They get bigger and bigger up to around 10 solar masses, then all the sudden they get to millions or billions of solar masses, with no real middle ground. This puzzled scientists, who came up with the Quasi-Star Theory to explain it.
Credit:
The Wooshing King 