Light-particle-induced deexcitations of 3-1 and 2+2 resonances of 12C in extreme stellar conditions

The particle-induced deexcitations of the 9.64 MeV, 3-1 and 9.87 MeV, 2+2 resonances of 12C increase the 12C production rate in a very hot and dense stellar environment. The enhancements in 12C production in such environments were estimated for a particle (n, p, and alpha) density of 106 g/cm3 in the temperature range of T9 = 0.1 to 10. Enhancement due to neutron-induced deexcitation was found to be the maximum. The net 12C production rate due to the combined contributions from 7.65 (Hoyle state), 9.64, and 9.87 MeV states is much higher compared to the rate adopted by NACRE compilation. In case of a typical collapsing massive star with temperature dependent densities, for any of the 3-1 or 2+2 resonances, the enhancement factor due to n, p, and alpha-induced deexcitations together can be as high as 600.