Constraining the 12C+12C fusion cross section for astrophysics

The C-12+C-12 reaction is one of the single most important nuclear reactions in astrophysics. It strongly influences late evolution of massive stars as well as the dynamics of type Ia supernovae and x-ray superbursts. An accurate estimation of the cross section at relevant astrophysical energies is extremely important for modeling these systems. However, the situation is complicated by the unpredictable resonance structure observed at higher energies. Two recent studies at Notre Dame have produced results which help reduce the uncertainty associated with this reaction. The first uses correlations with the isotope fusion systems, C-12+C-13 and C-13+C-13, to establish an upper limit on the resonance strengths in C-12+C-12. The other focuses on the specific channel C-12+C-12 -> Mg-23+n and its low-energy measurement and extrapolation which is relevant to s-process nucleosynthesis. The results from each provide important constraints for astrophysical models.