Electron capture (${}_Z^{A}X+e^{-}⟶{}_{Z-1}^{A}Y+{\nu }_e$)

A nucleus can capture an electron when energetically allowed, converting a proton into a neutron and emitting an electron neutrino. Beryllium-7 electron capture participates in one of the proton-proton chain branches. Stellar capture rates depend on ionization, mass density and electron phase space.