How many nucleosynthesis processes exist at low metallicity?

TL;DR

This paper investigates whether two nucleosynthesis processes can explain the heavy element abundances in low-metallicity stars, using a site-independent method to separate their contributions and constrain astrophysical conditions.

Contribution

It introduces a novel approach to disentangle the contributions of two nucleosynthesis processes to stellar abundances at low metallicity.

Findings

Two processes can largely explain observed abundance patterns.

The method quantifies each process's contribution to elements like Sr, Zr, Ba, Eu.

Constraints on supernova neutrino-driven wind conditions are derived.

Abstract

Abundances of low-metallicity stars offer a unique opportunity to understand the contribution and conditions of the different processes that synthesize heavy elements. Many old, metal-poor stars show a robust abundance pattern for elements heavier than Ba, and a less robust pattern between Sr and Ag. Here we probe if two nucleosynthesis processes are sufficient to explain the stellar abundances at low metallicity, and we carry out a site independent approach to separate the contribution from these two processes or components to the total observationally derived abundances. Our approach provides a method to determine the contribution of each process to the production of elements such as Sr, Zr, Ba, and Eu. We explore the observed star-to-star abundance scatter as a function of metallicity that each process leads to. Moreover, we use the deduced abundance pattern of one of the nucleosynthesis components to constrain the astrophysical conditions of neutrino-driven winds from core-collapse supernovae.