A POSSIBLE MODEL OF SUPERNOVAE - DETONATION OF 12C

Stars of intermediate mass (4 M⊙≲M≲9 M⊙) may ignite the12C+12C reaction explosively because of the high degree of electron degeneracy in their central regions. After the exhaustion of helium burning in the core of such stars, a helium-burning shell develops which is thermally unstable. Approximating this shell by suitable boundary conditions, the subsequent evolution of the core is examined quantitatively by standard techniques. An explosive instability due to ignition and detonation of12C+12C develops at a central density ρ{variant}c ∼ 2 × 109. Subsequent hydrodynamic expansion is computed; final velocities of expansion up to v∼20 000 km/sec are found. The star is totally disrupted; no condensed remnant is left. Such an explosion may be a plausible model for a significant fraction of supernovae. Investigation of the relevant nuclear reaction network shows that the entire core (Mcore∼1.37 M⊙) is processed through12C burning,16O burning and silicon burning. Significant amounts of56Ni are produced. This nucleosynthesis is critically sensitive to the exact central density at which the12C+12C reaction ignites; several factors which affect this critical density are discussed. A brief summary of other supernovae thories which have been expounded in detail is presented for comparison. © 1969 D. Reidel Publishing Company.