CNO bicycle framework: 4p → α + 2e⁺ + 2ν_e; CNO catalysts (C, N, O) conserved modulo cycle

The CNO (carbon-nitrogen-oxygen) bicycle — the principal hydrogen-burning path in stars heavier than ~1.3 M_☉ (including main-sequence stars of spectral type F and earlier). Net reaction: four protons are fused into one α particle with…