Super and massive AGB stars - III. nucleosynthesis in metal-poor and very metal-poor stars - Z = 0.001 and 0.0001
We present a new grid of stellar models and nucleosynthetic yields for super-AGB stars with metallicities Z = 0.001 and 0.0001, applicable for use within galactic chemical evolution models. Contrary to more metal-rich stars where hot bottom burning is the main driver of the surface composition, in t...
| Autores: | , , , , , |
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| Formato: | artículo |
| Fecha de publicación: | 2014 |
| País: | España |
| Recursos: | Universitat Politècnica de Catalunya (UPC) |
| Repositorio: | UPCommons. Portal del coneixement obert de la UPC |
| Idioma: | inglés |
| OAI Identifier: | oai:upcommons.upc.edu:2117/27588 |
| Acesso em linha: | https://hdl.handle.net/2117/27588 https://dx.doi.org/10.1093/mnras/stu571 |
| Access Level: | acceso abierto |
| Palavra-chave: | Nuclear reactions Asymptotic giant branch stars Nucleosynthesis Globular clusters: individual: NGC 2808 ISM: abundances nucleosynthesis abundances Stars: AGB and post-AGB Reaccions nuclears Àrees temàtiques de la UPC::Física::Astronomia i astrofísica |
| Resumo: | We present a new grid of stellar models and nucleosynthetic yields for super-AGB stars with metallicities Z = 0.001 and 0.0001, applicable for use within galactic chemical evolution models. Contrary to more metal-rich stars where hot bottom burning is the main driver of the surface composition, in these lower metallicity models the effect of third dredge-up and corrosive second dredge-up also have a strong impact on the yields. These metal-poor and very metal-poor super-AGB stars create large amounts of 4He, 13C, 14N and 27Al as well as the heavy magnesium isotopes 25Mg and 26Mg. There is a transition in yield trends at metallicity Z ˜ 0.001, below which we find positive yields of 12C, 16O, 15N and 28Si, which is not the case for higher metallicities. We explore the large uncertainties derived from wind prescriptions in super-AGB stars, finding ˜2 orders of magnitude difference in yields of 22Ne, 23Na, 24, 25, 26Mg, 27Al and our s-process proxy isotope g. We find inclusion of variable composition low-temperature molecular opacities is only critical for super-AGB stars of metallicities below Z ˜ 0.001. We analyse our results, and those in the literature, to address the question: Are super-AGB stars the polluters responsible for extreme population in the globular cluster NGC 2808? Our results, as well as those from previous studies, seem unable to satisfactorily match the extreme population in this globular cluster |
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