But the neutron stars are still quite large. This is because the electrons are about 1000 times as longer in how much space they require to sit in that system, than the neutrons. the neutrons are heavy hard attitude guys, they will go no where. But the electrons while occupy such a large couch are far far less heavier than are neutron. So they are basically whats called “soft”. They are long legged and eat less energy and when vanish the neutron stars have collapsed into an adjacent mass state but quite so very smaller in volume, a 1000 times, smaller.
So two things happened that are called supernovae (that is super star phenomena).
1. (Type Ia supernovae) White dwarf > induced by atomic disintegration due to gravity pressure > Core of the star
2. (Core collapse supernovae) Core of the star > induced further by emission of electrons > neutron star