Estimating R-Process Yields from Abundances of the Metal-Poor Stars

TL;DR

This study analyzes metal-poor star abundances to identify the astrophysical sites of the r-process, estimating yields from supernovae and explaining observed abundance patterns through mixing models.

Contribution

It determines the progenitor mass range for weak r-process supernovae and estimates the yields of the main r-process based on stellar abundance data.

Findings

Weak r-process occurs in supernovae with progenitor masses of 11-26 solar masses.

Main r-process yields are derived from abundance comparisons and supernova models.

The observed abundance ratios can be explained by mixing weak and main r-process contributions.

Abstract

The chemical abundances of metal-poor stars provide important clues to explore stellar formation history and set significant constraints on models of the r-process. In this work, we find that the abundance patterns of the light and iron group elements of the main r-process stars are very close to those of the weak r-process stars. Based on a detailed abundance comparison, we find that the weak r-process occurs in supernovae with a progenitor mass range of $\sim11-26M_{\odot}$. Using the SN yields given by Heger & Woosley and the abundances of the weak r-process stars, the weak r-process yields are derived. The SNe with a progenitor mass range of $15M_{\odot}<M<26M_{\odot}$ are the main sites of the weak r-process and their contributions are larger than 80%. Using the abundance ratios of the weak r-process and the main r-process in the solar system, the average yields of the main r-process are estimated. The observed correlations of the [neutron-capture/Eu] versus [Eu/Fe] can be explained by mixing of the two r-process abundances in various fractions.