T-2, Nuclear and Particle Physics, Astrophysics and Cosmology

Nucleosynthesis modes in the high-entropy-wind of type II supernovae

Karl-Ludwig Kratz

The exact conditions for the supernova high-entropy wind (HEW) as one of the favored sites for the rapid neutroncapture (r-) process still cannot be reproduced selfconsistently in present hydrodynamic simulations. Therefore, we have performed large-scale network calculations within a parameterized HEW model to constrain the necessary conditions for a full r-process, and to compare our results with recent astronomical observations. A superposition of entropy trajectories with model-inherent weightings results in an excellent reproduction of the overall Solar-System isotopic abundances (Nr,!) of the main r-process elements beyond Sn. For the lighter r-elements, our HEW model supports earlier qualitative ideas about a multiplicity of nucleosynthesis processes in the Fe-group region. In the HEW scenario, these suggestions are quantified, and the origin of the missing abundances to Nr,! is determined to be a rapid primary charged-particle (!-) process, thus excluding a classical weak neutron-capture component. This explains the recent halo-star observations of a non-correlation of Cu - Ge and Sr - Zr with metallicity [Fe/H] and r-process enrichment [Eu/H]. Moreover, for the first time a partial correlation with the main r-process is identified for Ru and Pd.


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