Today I want to talk about a very funny thing, the Chandrasekhar limit.
Subrahmanyan Chandrasekhar was an Indian physicist with very complicated name whose greatest achievement was making the mathematical expression that allows us to know if something is going to collapse and that.
This limit will indicate if a star when it collapses from lack of hydrogen, will become a black hole or a neutron star.
Remember that in the life of a star is burning hydrogen into helium through fusion that occurs in its core. The problem is when you can not merge more hydrogen because not enough, and if there is too much helium. This, star, expel the outer layers where materials formed (remaining hydrogen and helium) are leaving the central area, which is a soup proton very dense, gravity collapse because there are not enough electrons serve ( remember, weak force) to subtract against gravity causing protons and electrons join creating neutrons.
So when a star exceeds the Chandrasekhar limit can become a neutron star or a black hole.
The problem is that there is a third theoretical possibility is that it becomes a quark star attraction and if the mass is greater. But this case has not been seen only believed to exist.