It's a reversible equilibrium reaction. Neutron <-> proton + electron + antinutrino + energy. The forward reaction is beta decay, and is favored by lone neutron

It's a reversible equilibrium reaction. Neutron <-> proton + electron + antinutrino + energy. The forward reaction is beta decay, and is favored by lone neutrons and by the neutrons in some atomic nuclei (i.e. radioactive isotopes that undergo beta decay). Presumably the half-life of a nucleous is determined by the degree of favorability of the beta decay reaction within that nucleus. The article already mentions that the reverse reaction (neutron formation) is favored under the conditions of a neutron star, since the pressure favors the side of the reaction with fewer particles. The gravitational potential energy released as the neutron star collapses supplies the energy required for the reverse reaction. Disclaimer: I am not a physicist.