Reaction rate for carbon burning in massive stars

Abstract

Carbon burning is a critical phase for nucleosynthesis in massive stars. The conditions for igniting this burning stage, and the subsequent isotope composition of the resulting ashes, depend strongly on the reaction rate for $^{12}\mathrm{C}+^{12}\mathrm{C}$ fusion at very low energies. Results for the cross sections for this reaction are influenced by various backgrounds encountered in measurements at such energies. In this paper, we report on a new measurement of $^{12}\mathrm{C}+^{12}\mathrm{C}$ fusion cross sections where these backgrounds have been minimized. It is found that the astrophysical $S$ factor exhibits a maximum around ${E}_{\mathrm{cm}}=3.5--4.0$ MeV, which leads to a reduction of the previously predicted astrophysical reaction rate.