Grids of stellar models with rotation

VIII. Models from 1.7 to 500 M_⊙ at metallicity Z = 10⁻⁵

¹ Observatoire de Genève, Chemin Pegasi 51, 1290 Versoix, Switzerland
² SISSA, Via Bonomea 365, 34136 Trieste, Italy
³ Department of Physics, Faculty of Science, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
⁴ Astrophysics Group, Keele University, Keele, Staffordshire ST5 5BG, UK
⁵ Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8583, Japan
⁶ STAR Institute, Université de Liège, Liège, Belgium

Received: 29 March 2024
Accepted: 19 June 2024

Abstract

Context. Grids of stellar evolution models with rotation using the Geneva stellar evolution code (GENEC) have been published for a wide range of metallicities.

Aims. We introduce the last remaining grid of GENEC models, with a metallicity of Z = 10⁻⁵. We study the impact of this extremely metal-poor initial composition on various aspects of stellar evolution, and compare it to the results from previous grids at other metallicities. We provide electronic tables that can be used to interpolate between stellar evolution tracks and for population synthesis.

Methods. Using the same physics as in the previous papers of this series, we computed a grid of stellar evolution models with GENEC spanning masses between 1.7 and 500 M_⊙, with and without rotation, at a metallicity of Z = 10⁻⁵.

Results. Due to the extremely low metallicity of the models, mass-loss processes are negligible for all except the most massive stars. For most properties (such as evolutionary tracks in the Hertzsprung-Russell diagram, lifetimes, and final fates), the present models fit neatly between those previously computed at surrounding metallicities. However, specific to this metallicity is the very large production of primary nitrogen in moderately rotating stars, which is linked to the interplay between the hydrogen- and helium-burning regions.

Conclusions. The stars in the present grid are interesting candidates as sources of nitrogen-enrichment in the early Universe. Indeed, they may have formed very early on from material previously enriched by the massive short-lived Population III stars, and as such constitute a very important piece in the puzzle that is the history of the Universe.