Nucleosynthesis Modes in the High-Entropy-Wind of Type II Supernovae: Comparison of Calculations with Halo-Star Observations

TL;DR

This study explores the high-entropy wind of Type II supernovae as a site for the r-process, using extensive calculations and observations to identify conditions that reproduce elemental abundance patterns in halo stars.

Contribution

It provides detailed modeling of the HEW conditions and compares them with stellar observations, revealing insights into the production of r-process elements and their relation to lighter elements.

Findings

Successful reproduction of the r-process residual pattern beyond Sn.

Indication of a transition from separate sources to co-production of lighter and heavier elements.

Observational data support partial correlations between certain elements, confirming model predictions.

Abstract

While the high-entropy wind (HEW) of Type II supernovae remains one of the more promising sites for the rapid neutron-capture (r-) process, hydrodynamic simulations have yet to reproduce the astrophysical conditions under which the latter occurs. We have performed large-scale network calculations within an extended parameter range of the HEW, seeking to identify or to constrain the necessary conditions for a full reproduction of all r-process residuals N_{r,\odot}=N_{\odot}-N_{s,\odot} by comparing the results with recent astronomical observations. A superposition of weighted entropy trajectories results in an excellent reproduction of the overall N_{r,\odot}-pattern beyond Sn. For the lighter elements, from the Fe-group via Sr-Y-Zr to Ag, our HEW calculations indicate a transition from the need for clearly different sources (conditions/sites) to a possible co-production with r-process elements, provided that a range of entropies are contributing. This explains recent halo-star observations of a clear non-correlation of Zn and Ge and a weak correlation of Sr - Zr with heavier r-process elements. Moreover, new observational data on Ru and Pd seem to confirm also a partial correlation with Sr as well as the main r-process elements (e.g. Eu).