In simple words, black holes are created due to Implosion of stars.
But all stars which implode does not form black holes. It clearly depends on mass of stars.
A star's life is always in equilibrium with the force of nuclear fusion of Hydrogen to Helium(Stars are made of hydrogen atoms) and force of Gravitational pull.
Once stars run out of hydrogen atoms, the only remaining force is gravitational pull.
The further process clearly depends on the mass of star. We can categorize mass of star in three types :
1. Stars which have mass less than sun
(Less than 1 solar mass)
2. Stars which are about the mass of sun(1 - 1.4 solar mass)
3. Stars which are much more massive than sun(more than 20 solar mass)
Lets study all three cases briefly one by one.
1. For stars which have mass less than that of sun :
When these stars run out of hydrogen atoms then there are no more nuclear reactions to fight gravity. The repulsive forces among the electrons within the star eventually create enough pressure to halt further gravitational process.
2. For stars which are about the mass of sun:
These stars end state will be a White drawf. No more fusion takes place and only heavier elements like oxygen, carbon remain out.It stars to cool down slowly.But it does not collapse further due to Electron degeneracy pressure.
3.For stars more massive than sun :
The fusion process continues further up the periodic table to silicon, aluminium, potassium and so on up to ferrous(iron). No energy can be produced by fusing iron atoms together. Its the Stellar equivalent to ash. It will get to white dwarf stage and keep collapsing. It will become a neutron star and still it shrinks. It gets denser and denser and collapses to a point where all mass of star is contained within the Schwarzschild radius and becomes a BLACK HOLE.
But all stars which implode does not form black holes. It clearly depends on mass of stars.
A star's life is always in equilibrium with the force of nuclear fusion of Hydrogen to Helium(Stars are made of hydrogen atoms) and force of Gravitational pull.
Once stars run out of hydrogen atoms, the only remaining force is gravitational pull.
The further process clearly depends on the mass of star. We can categorize mass of star in three types :
1. Stars which have mass less than sun
(Less than 1 solar mass)
2. Stars which are about the mass of sun(1 - 1.4 solar mass)
3. Stars which are much more massive than sun(more than 20 solar mass)
Lets study all three cases briefly one by one.
1. For stars which have mass less than that of sun :
When these stars run out of hydrogen atoms then there are no more nuclear reactions to fight gravity. The repulsive forces among the electrons within the star eventually create enough pressure to halt further gravitational process.
2. For stars which are about the mass of sun:
These stars end state will be a White drawf. No more fusion takes place and only heavier elements like oxygen, carbon remain out.It stars to cool down slowly.But it does not collapse further due to Electron degeneracy pressure.
3.For stars more massive than sun :
The fusion process continues further up the periodic table to silicon, aluminium, potassium and so on up to ferrous(iron). No energy can be produced by fusing iron atoms together. Its the Stellar equivalent to ash. It will get to white dwarf stage and keep collapsing. It will become a neutron star and still it shrinks. It gets denser and denser and collapses to a point where all mass of star is contained within the Schwarzschild radius and becomes a BLACK HOLE.
ANIKET KULKARNI
Footnotes:
Image source : Black hole image
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