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A lot of what is written in the question is not correct. The URCA process would be cycles of beta decay followed by inverse beta decay as follows. $$n \rightarrow p + e + \bar{\nu_e}$$ $$ p + e \rightarrow n + \nu_e$$ The neutrinos escape from the star, carrying away energy. The URCA process is very important during the collapse to a neutron star state, ...


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The reason why a massive star does not immediately collapse to a black hole is radiation pressure. When a star is in that phase of its life called Main Sequence (MS), its luminosity depends approximately on its mass roughly as $M^4$. This means a star 10 times as massive as the Sun would be 10,000 times more luminous. This enormous luminosity is mostly ...


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It wasn't a black hole because the density wasn't sufficiently high. The density was lower than what is needed for a black hole because the volume was larger. The volume was larger because the atoms (mostly hydrogen) were kept away from each other by the pressure produced by the fusion processes. Once the fusion processes stop, this source of repulsion ...


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Light with wavelength $\lambda\gg10\,\mathrm{km}$ can pass around a neutron star thanks to diffraction, even if the star is made of a perfectly absorbing material. That's exceptionally low-energy radio waves, though, and pretty different from what you probably had in mind.


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The answer given by Kyle refers of course only to the surface or photospheric temperature of the neutron star - the temperature of the layer from which photons can escape to reach an observer. In these outer layers the relationship between temperatures and particle motions is more-or-less consistent with the "everyday" Maxwell-Boltzmann picture referred to ...



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