2
votes
1answer
83 views

Why does a star beyond a certain mass limit (Chandrasekhar limit) only become a black hole?

Why does a star beyond a certain mass limit (Chandrasekhar limit) only become a black hole? A star is first made of hydrogen, it undergoes nuclear fussion reaction combining into helium and ...
14
votes
5answers
3k views

Why does a star collapse under its own gravity when the gravity at its centre is zero?

The gravity at the centre of a star is zero as in the case of any uniform solid sphere with some mass. When a massive star dies, why does it give rise to a black hole at it's centre? I know how to ...
0
votes
1answer
63 views

What is the mass required for a star to have the gravity equivalent to a black hole?

At what mass does the light from stars ( I am talking about stars and not black holes) fail to escape the star's gravity? Is it the same (minimum) mass required for an object to be called a black ...
4
votes
2answers
96 views

What reason(s) exist to suppose that all degeneracy pressures can be overcome in Black-Hole formation?

In models of stellar collapse to a black hole, it is a given that density increases without bound towards a singularity. Electron degeneracy I get. Neutron degeneracy I get. I assume there's some ...
2
votes
1answer
204 views

The role of dark matter in black holes and star formation

In my understanding, there exists a critical mass for which a star needs to be in order for it to collapse into a black hole. This also applies to a certain critical density of gas in order for stars ...
4
votes
1answer
167 views

Why can't a stable star have radius 1 < r < 9/8 its Schwarzschild radius?

From http://www.spacetimetravel.org/ssm/ssm.html : A mass of 1.78 [in geometric units] corresponds to a ratio of radius to Schwarzschild radius of 9/8. Theory predicts that a smaller ratio is not ...