CNO-II cycle (${}^{15}\mathrm{N}\to {}^{16}\mathrm{O}\to {}^{17}\mathrm{F}\to {}^{17}\mathrm{O}\to {}^{14}\mathrm{N}$)

A branch of the CNO cycle proceeds through proton captures on nitrogen-15 and oxygen-16, beta-plus decay of fluorine-17, and ${}^{17}\mathrm{O}(p,\alpha ){}^{14}\mathrm{N}$. Returning through oxygen-15 and nitrogen-15 closes the cycle. It also catalyzes the conversion of four protons into helium-4, with branch-dependent neutrino loss.