Formation of neutron stars and black holes.

[LogicalAcid]

First of all, I know that that very large stars tend to form black holes, and smaller stars, but still massive in comparison to our sun, tend to form neutron stars. My question is, if matter is lost when a star collapses into a black hole, but can still form one, why is it that it is a star first if it has more mass than the original black hole?

 

[jobigoud]

why is it that it is a star first if it has more mass than the original black hole?

During its normal life, the nuclear reactions in the star's core creates outward pressure that compensate the gravity. It is only when the star has radiated most of its energy from nuclear reactions that it has trouble fighting gravity. Depending on its mass at this point, it may collapse to a white dwarf, a neutron star, or a black hole.

 

[StevieBarratt]

I understand that a neutron star is a star so effected by gravity that the electron shells have been foced into the protons to form neutrons. Presumably these neutrons are packed in tightly together as they have no repulsive charges and are under enormous gravitational pressure. Also, most of an atom is empty space between the nucleus and the electon quanta. If there are no electrons, does that mean that we have effectively a supermassive atomic nucleus? Or is that black hole territory? Or (most likely) I'm missing something!

 

[Kracatoan]

https://www.physicsforums.com/showthread.php?t=461582

covers some of the stuff you are talking about.

 

[sardar]

This is a great question and one that has been a subject of ongoing research and debate in the scientific community. The formation of neutron stars and black holes is a result of the death of a massive star, known as a supernova explosion.

When a star runs out of fuel, it can no longer sustain the nuclear fusion reactions in its core that keep it stable. This causes the core of the star to collapse under its own gravity, resulting in a supernova explosion. The collapse of the core can continue even after the explosion, leading to the formation of either a neutron star or a black hole.

The main difference between the two is the mass of the original star. Neutron stars typically form from stars with masses between 8 and 20 times that of our sun, while black holes form from stars with masses greater than 20 times that of our sun. This is because the gravitational force of a more massive star is strong enough to overcome the repulsive force of the neutron degeneracy pressure, which is what keeps a neutron star from collapsing further.

So, why does a star first form before collapsing into a black hole if it has more mass? This is because the formation of a black hole is a gradual process. As the star collapses, it becomes more and more dense, and its gravity becomes stronger. At a certain point, the gravity becomes so strong that even light cannot escape its pull, and a black hole is formed.

In contrast, a neutron star is formed when the core of the star collapses to a point where the neutrons are packed so tightly that they resist further collapse. This results in a very dense and compact object, but one that is not dense enough to form a black hole.

In summary, the formation of neutron stars and black holes is a complex process that depends on the mass of the original star and the strength of its gravitational force. While a star may have more mass than a black hole, it is the gradual process of collapse that leads to the formation of these two distinct objects.