Co-production of light p-, s- and r-process isotopes in the high-entropy wind of type II supernovae

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We have performed large-scale nucleosynthesis calculations within the high-entropy-wind (HEW) scenario of type II supernovae. The primary aim was to constrain the conditions for the production of the classical "p-only" isotopes of the light trans-Fe elements. We find, however, that for electron fractions in the range 0.458 ≤ Yₑ ≤ 0.478, sizeable abundances of p-, s- and r-process nuclei between ⁶⁴Zn and ⁹⁸Ru are coproduced in the HEW at low entropies (S ≤ 100) by a primary charged-particle process after an α-rich freezeout. With the above Yₑ -- S correlation, most of the predicted isotopic abundance ratios within a given element (e.g. ⁶⁴Zn(p)/⁷⁰Zn(r) or ⁹²Mo(p)/⁹⁴Mo(p)), as well as of neighboring elements (e.g. ⁷⁰Ge(s+p)/⁷⁴Se(p) or ⁷⁴Se(p)/⁷⁸Kr(p)) agree with the observed Solar-System ratios. Taking the Mo isotopic chain as a particularly challenging example, we show that our HEW model can account for the production of all 7 stable isotopes, from "p-only" ⁹²Mo, via "s-only" ⁹⁶Mo up to "r-only" ¹⁰⁰Mo. Furthermore, our model is able to reproduce the isotopic composition of Mo in presolar SiC X-grains.