Astrophysical factor and rate of the ¹²C+¹²C reaction due to a resonance at an energy E_R = 1.3 MeV (dashed line), 1.5 MeV (solid line), and 1.7 MeV (dot-dashed line), with resonance strengths of 16 meV, 9.2 meV, and 4.1 meV, respectively. Top: modified astrophysical factor as a function of energy. The bar at the bottom right shows the maximal astrophysical factor measured by S07 at an energy of  ~2.1 MeV (σ < 0.8 nb), which is the most constraining low energy measurement to date. The quoted strengths of the resonances would be compatible with a σ two orders of magnitude smaller than that measured by S07 (if the resonance width is Γ_R ≈ 10 keV). Bottom: ratio of our ¹²C+¹²C reaction, accounting for a LER, to the CF88 reaction rate, as a function of temperature. The dotted line close to the horizontal axis is the ratio of the rate accounting for the resonance found by S07 to the CF88 rate. The arrows mark the temperature ranges relevant to carbon ignition, carbon simmering, and the explosive burning in a subsonic flame or a detonation. The gap between carbon simmering and flames reflects the dominance of thermal conduction and shock heating over nuclear energy release in stationary explosive burning fronts.