Nucleosynthesis Modes in the High‐Entropy‐Wind Scenario of Type II Supernovae

Abstract

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 weightings results in an excellent reproduction of the overall Solar System (SS) isotopic r‐process residuals (Nr,⊙), 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, an S‐dependent superposition of (i) a normal α‐component directly producing stable nuclei, including s‐only isotopes, and (ii) a component from a neutron‐rich α‐freezeout followed by the rapid recapture of β‐delayed neutrons (βdnrpar; emitted from the far‐unstable seed nuclei is indicated. In agreement with several recent halo‐star observations in the 60<A<110 region, our HEW model confirms a Z‐dependent non‐correlation, respectively partial correlation with the heavier “main” r‐process elements.