Why don't electrons fall into neutrons in neutron stars?

[Attu]

For instance let's take that a neutron star mass is so high that the gravitational force is more than the coulumb force. If this happens then then the electrons will go down and alpha particle will be left . This is not observed in the star so how will the particle stay normal

By the way I am thirteen years so please correct me if I am wrong.

 

[jedishrfu]

Sadly, the electrons will merge with the protons to create neutrons and thus the whole star becomes composed of neutrons. Neutron degeneracy pressure keeps it from collapsing further until of course, it becomes more massive such that gravity overcomes the degeneracy.

Degeneracy pressure is like two magnets repelling against one another. Neutrons do the same thing ie no two fermions can occupy the same space at the same time.



https://en.wikipedia.org/wiki/Neutron_star

https://en.wikipedia.org/wiki/Degenerate_matter#Neutron_degeneracy

 

[Nugatory]

If this happens then then the electrons will go down and alpha particle will be left .

A helium atom is a nucleus consisting of two neutrons and two protons, with two electrons outside. When an electron is forced into the nucleus we get the reaction $e+p\rightarrow n+\nu$ and the neutino flies away leaving a neutron behind.

When both electrons are forced into the nucleus (two neutrons and two protons) we end up with four neutrons, and that's how neutron stars are formed.

 

[PeterDonis]

let's take that a neutron star mass is so high that the gravitational force is more than the coulumb force.

It might help to realize that, even before we get to neutron stars, we have white dwarfs, in which the ordinary structure of atoms is already broken down, so in that sense the "gravitational force" (gravity is not really a force in General Relativity, but we don't need to go into all that for this particular topic) already overwhelms the Coulomb force in white dwarfs, which are far less dense and typically less massive than neutron stars. In white dwarfs, the electrons are free to move without being bound to particular nuclei, and the white dwarf is supported against its own gravity by the degeneracy pressure of the electrons.

The difference in neutron stars is that the pressure required to support them against their own gravity is so large (about a million times larger than in white dwarfs) that electron degeneracy pressure is not sufficient, so the electrons get forced into the nuclei by the weight of the star, with electrons and protons combining to form neutrons. Then the star is held up by neutron degeneracy pressure, which is capable, at neutron star densities, of doing the job.

https://en.wikipedia.org/wiki/White_dwarf

 

[Attu]

Thanks for answering bi had this doubt for a long time

 

[PeterDonis]

Thanks for answering

You're welcome!

 

[OCR]

Neutron star paradox. . .

Here's a subtype that's. . . even more weird . .

These magnetic fields are a hundred million times stronger than any man-made magnet,
and quadrillions of times more powerful than the field surrounding Earth.

.