Helium-3
= Helium-3
{title2=$^3\mathrm{He}$}
{wiki}
This stable <helium> isotope contains two <protons> and one <neutron>. In solar proton-proton burning it is an intermediate: two such nuclei can form <helium-4> and return two <protons>, or one can capture <helium-4> to enter the second chain branch. The balance between production and destruction determines the <helium-3 equilibrium abundance> and its <helium-3 relaxation time>.