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Relative Importance of Convective Uncertainties in Massive Stars

Kaiser, Etienne A; Hirschi, Raphael; Arnett, W David; Georgy, Cyril; Scott, Laura J A; Cristini, Andrea

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Authors

Etienne A Kaiser

W David Arnett

Cyril Georgy

Laura J A Scott

Andrea Cristini



Abstract

In this work, we investigate the impact of uncertainties due to convective boundary mixing (CBM), commonly called ‘overshoot’, namely the boundary location and the amount of mixing at the convective boundary, on stellar structure and evolution. For this we calculated two grids of stellar evolution models with the MESA code, each with the Ledoux and the Schwarzschild boundary criterion, and vary the amount of CBM. We calculate each grid with the initial masses 15, 20 and $25\, \rm M_ødot$. We present the stellar structure of the models during the hydrogen and helium burning phases. In the latter, we examine the impact on the nucleosynthesis. We find a broadening of the main-sequence with more CBM, which is more in agreement with observations. Furthermore during the core hydrogen burning phase there is a convergence of the convective boundary location due to CBM. The uncertainties of the intermediate convective zone remove this convergence. The behaviour of this convective zone strongly affects the surface evolution of the model, i.e. how fast it evolves red-wards. The amount of CBM impacts the size of the convective cores and the nucleosynthesis, e.g. the 12C to 16O ratio and the weak s-process. Lastly, we determine the uncertainty that the range of parameter values investigated introduce and we find differences of up to $70%$ for the core masses and the total mass of the star.

Citation

Kaiser, E. A., Hirschi, R., Arnett, W. D., Georgy, C., Scott, L. J. A., & Cristini, A. (2020). Relative Importance of Convective Uncertainties in Massive Stars. Monthly Notices of the Royal Astronomical Society, 496(2), 1967-1989. https://doi.org/10.1093/mnras/staa1595

Journal Article Type Article
Acceptance Date May 30, 2020
Online Publication Date Jun 8, 2020
Publication Date 2020-08
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 496
Issue 2
Pages 1967-1989
DOI https://doi.org/10.1093/mnras/staa1595
Keywords convection, stars: evolution, stars: interiors, stars: massive, nucleosynthesis
Publisher URL https://doi.org/10.1093/mnras/staa1595

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