Insights on the First Stars from CEMP-no Stars

Choplin, Arthur; Meynet, Georges; Maeder, André; Hirschi, Raphael; Ekström, Sylvia; Chiappini, Cristina

Abstract

CEMP-no stars (Carbon-Enhanced metal-poor stars with no or few s- or r-elements) are long-lived low mass stars presenting a very low iron content and overabundances of carbon relatively to the sun. Their chemically peculiar abundance pattern could be inherited from a previous rotating massive star, also called the source star. Thanks to the rotational mixing at work in the source star, the chemical species transit from a hydrogen burning region to a helium burning region, leading to a varied and rich nucleosynthesis. Depending on the initial rotation of the source star, the internal mixing is more or less important, leading to a different nucleosynthesis. We suggest first that the observed 12C/13C ratio might constrain the mass cut of the source star. Then, we apply that constraint on a set of 20M⊙
source stars models with various initial rotation rates. We show that the ejecta of these 20M⊙ models match rather well the observed scatters of C/H, N/H, O/H, and Na/H of the CEMP-no sample. The impact of changing the reaction rate of 27Al(p, γ)28Si is also investigated.

Citation

Choplin, A., Meynet, G., Maeder, A., Hirschi, R., Ekström, S., & Chiappini, C. Insights on the First Stars from CEMP-no Stars. Presented at Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016), Niigata, Japan

• Presentation Conference Type: Conference Paper (published)
• Conference Name: Proceedings of the 14th International Symposium on Nuclei in the Cosmos (NIC2016)
• Publication Date: Feb 28, 2017
• Deposit Date: Jun 16, 2023
• Journal: JPS Conference Proceedings
• Print ISSN: 2435-3892
• Publisher: Thieme Gruppe
• Peer Reviewed: Peer Reviewed
• DOI: https://doi.org/10.7566/jpscp.14.020202
• Public URL: https://keele-repository.worktribe.com/output/469065