Khalil Farouqi

University of Chicago and Argonne

Explosive nucleosynthesis in the high-entropy wind of core-collapse supernovae

In an attempt to constrain the astrophysical conditions for the nucleosynthesis of the classical r-process elements beyond Fe, we have performed large-scale dynamical network calculations within the model of an adiabatically expanding high-entropy wind (HEW) of type II supernovae (SN II). A superposition of several entropy-components (S) with model-inherent weighting results in an excellent reproduction of the overall Solar System (SS) isotopic r-process residuals, as well as the more recent observations of elemental abundances of metal-poor, r-process-rich halo-stars in the early Galaxy. For the heavy r-process elements beyond Sn, our HEW model predicts a robust abundance pattern up to the Th, U r-chronometer region. For the lighter neutron-capture region, and S-dependent superposition of (i) a normal a-component directly producing stable nuclei, including s-only isotopes, and (ii) a component from a neutron-rich a-freezout followed by the rapid recapture of b-delayed neutrons emitted from the far-unstable seed nuclei is indicated.

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