The impact of wind mass loss on nucleosynthesis and yields of very massive stars at low metallicity

¹ Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG N. Ireland, UK
² Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UK
³ Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK
⁴ Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan
⁵ School of Physics, Engineering and Technology, University of York, York YO10 5DD, UK

^⋆ Corresponding author: e.higgins@qub.ac.ukat

Received: 16 December 2024
Accepted: 15 April 2025

Abstract

The chemical feedback from stellar winds in low metallicity (Z) environments is key to understanding the evolution of globular clusters and the early Universe. With a disproportionate amount of mass lost from the most massive stars (M > 100 M_⊙) and an excess of such stars expected at the lowest metallicities, their contribution to the enrichment of the early pristine clusters could be significant. In this work, we examine the effect of mass loss at low metallicity on the nucleosynthesis and wind yields of (very) massive stars. We calculated stellar models with initial masses ranging from 30 to 500 M_⊙ during core hydrogen and helium burning phases at four metallicities ranging from 20% Z_⊙ down to 1% Z_⊙. We provide the ejected masses and net yields for each grid of models. While mass-loss rates decrease with Z, we find that not only are wind yields significant, but the nucleosynthesis is also altered due to the change in central temperatures, and therefore it also plays a role. We find that 80–300 M_⊙ models can produce large quantities of Na-rich and O-poor material, which is relevant for the observed Na-O anti-correlation in globular clusters.