Tungsten in barium stars
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arXiv
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| Auteurs principaux: | , , , , , |
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| Format: | Preprint |
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2024
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| _version_ | 1866916094886805504 |
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| author | Roriz, M. P. Lugaro, M. Junqueira, S. Sneden, C. Drake, N. Pereira, C. B. |
| author_facet | Roriz, M. P. Lugaro, M. Junqueira, S. Sneden, C. Drake, N. Pereira, C. B. |
| contents | Classical barium stars are red giants that received from their evolved binary companions material exposed to the \textit{slow} neutron-capture nucleosynthesis, i.e., the $s$-process. Such a mechanism is expected to have taken place in the interiors of Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) stars. As post-interacting binaries, barium stars figure as powerful tracers of the $s$-process nucleosynthesis, evolution of binary systems, and mechanisms of mass transfer. The present study is the fourth in a series of high-resolution spectroscopic analyses on a sample of 180 barium stars, for which we report tungsten (W, $Z=74$) abundances. The abundances were derived from synthetic spectrum computations of the W\,{\sc i} absorption features at 4\,843.8~Å and 5\,224.7~Å. We were able to extract abundances for 94 stars; the measured [W/Fe] ratios range from $\sim0.0$ to $2.0$ dex, increasing with decreasing of metallicity. We noticed that in the plane [W/Fe] versus [$s$/Fe] barium stars follow the same trend observed in post-AGB stars. The observational data were also compared with predictions of the {\sc fruity} and Monash AGB nucleosynthesis models. These expect values between $-0.20$ and $+0.10$ dex for the [W/hs] ratios, whereas a larger spread is observed in the program stars, with [W/hs] ranging from $-0.40$ to $+0.60$ dex. The stars with high [W/hs] ratios may represent evidence for the operation of the intermediate neuron-capture process at metallicities close to solar. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_09206 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Tungsten in barium stars Roriz, M. P. Lugaro, M. Junqueira, S. Sneden, C. Drake, N. Pereira, C. B. Solar and Stellar Astrophysics Classical barium stars are red giants that received from their evolved binary companions material exposed to the \textit{slow} neutron-capture nucleosynthesis, i.e., the $s$-process. Such a mechanism is expected to have taken place in the interiors of Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) stars. As post-interacting binaries, barium stars figure as powerful tracers of the $s$-process nucleosynthesis, evolution of binary systems, and mechanisms of mass transfer. The present study is the fourth in a series of high-resolution spectroscopic analyses on a sample of 180 barium stars, for which we report tungsten (W, $Z=74$) abundances. The abundances were derived from synthetic spectrum computations of the W\,{\sc i} absorption features at 4\,843.8~Å and 5\,224.7~Å. We were able to extract abundances for 94 stars; the measured [W/Fe] ratios range from $\sim0.0$ to $2.0$ dex, increasing with decreasing of metallicity. We noticed that in the plane [W/Fe] versus [$s$/Fe] barium stars follow the same trend observed in post-AGB stars. The observational data were also compared with predictions of the {\sc fruity} and Monash AGB nucleosynthesis models. These expect values between $-0.20$ and $+0.10$ dex for the [W/hs] ratios, whereas a larger spread is observed in the program stars, with [W/hs] ranging from $-0.40$ to $+0.60$ dex. The stars with high [W/hs] ratios may represent evidence for the operation of the intermediate neuron-capture process at metallicities close to solar. |
| title | Tungsten in barium stars |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2401.09206 |