Formation of neutron stars and black holes.

AI Thread Summary
Large stars typically evolve into black holes, while smaller, yet massive stars become neutron stars. During a star's life, nuclear reactions generate outward pressure that balances gravitational forces until energy is depleted. When this balance fails, the star's fate depends on its mass, leading to a collapse into a white dwarf, neutron star, or black hole. Neutron stars consist of tightly packed neutrons formed from protons and electrons under extreme gravity, raising questions about their structure compared to atomic nuclei. The discussion highlights the complexities of stellar evolution and the transition from stars to compact objects like neutron stars and black holes.
LogicalAcid
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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?
 
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LogicalAcid said:
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.
 
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!
 
https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
Why was the Hubble constant assumed to be decreasing and slowing down (decelerating) the expansion rate of the Universe, while at the same time Dark Energy is presumably accelerating the expansion? And to thicken the plot. recent news from NASA indicates that the Hubble constant is now increasing. Can you clarify this enigma? Also., if the Hubble constant eventually decreases, why is there a lower limit to its value?
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