What Is the Limit of the Gravitational Collision?

If a star gets too massive it explodes if it gets too hot because the reactions are occurring at a rate that's too fast. You don't see stars with masses above like 20 times the mass of the sun they're very very rare and the reason is that once you get really really hot you simply can't a crate material fast enough. The peer-reviewed literature in science articles on this suggest vast masses for some metal deficient and in particular population three stars.