Light elements synthesized in the He-layer and the H-rich envelope of a type II supernova—Influence of the adopted neutrino emission model—

In order to establish a suitable manner for finding presolar grains of supernova origin, we simulated the explosive nucleosynthesis of light elements, i.e., CNO-elements and X-elements (Li, Be, and B), in the He-layer and the H-rich envelope of a 16.2 M_⊙ supernova and calculated their final abundances and abundance ratios using the nuclear reaction network. We also investigated the response of the synthesized abundances of light elements to the change of strength and duration of the neutrino emission, about which we have not a precise knowledge. The obtained results are as follows. The amounts of ⁶Li and ⁹Be produced during the supernova explosion are quite small. The ratios of ⁶Li/⁷Li and ⁹Be/⁷Li are less than 2 × 10⁻⁴, which are much smaller than the corresponding solar-system values. The other X-elements and CNO-elements (except ¹²C and ¹⁶O) are synthesized, more or less, and their abundances depend strongly on the internal mass coordinate as well as the adopted neutrino emission model. However, ¹¹B/⁷Li ratio and isotopic ratios of CNO-elements are confined within one order of magnitude or so. On the basis of the above results, we finally proposed useful diagrams between two isotopic (elemental) ratios, which would help us to find presolar grains of supernova origin.