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| Natura: | Preprint |
| Pubblicazione: |
2025
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| Accesso online: | https://arxiv.org/abs/2510.20546 |
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| _version_ | 1866912665957302272 |
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| author | Takeda, Yoichi |
| author_facet | Takeda, Yoichi |
| contents | With an aim of clarifying the extent and parameter-dependence of compositional anomaly of barium in A-type stars, Ba abundances were spectroscopically determined based on BaII 6141/6496 lines for 89 (23 A-type and 66 F--G-type) main-sequence stars belonging to the members of Hyades cluster by taking into account the non-LTE effect and the hyper-fine-structure effect. While the non-LTE effect tends to strengthen lines in G stars, it acts in the direction of line weakening in the regime of A stars due to increasing imortance of overionization. The Ba abundances of G stars turned out almost constant (<A>= 2.33), indicating that the primordial composition of Ba in Hyades is mildly supersolar by ~+0.2dex. In contrast, A-type stars show Ba overabundances of considerably large dispersion (0~<[Ba/H]~<2). Since this Ba excess tends to increase with an increase/decrease in Teff/vsini, these two parameters may be essential for producing or controling the anomaly. Regarding Hyades F-type stars, their Ba abundances are not uniform but show a broad depression (by <~0.3dex) around Teff~6500K, interestingly coinciding with the location of Li-dip. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2510_20546 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Barium abundances of A--F--G type stars in the Hyades cluster Takeda, Yoichi Solar and Stellar Astrophysics With an aim of clarifying the extent and parameter-dependence of compositional anomaly of barium in A-type stars, Ba abundances were spectroscopically determined based on BaII 6141/6496 lines for 89 (23 A-type and 66 F--G-type) main-sequence stars belonging to the members of Hyades cluster by taking into account the non-LTE effect and the hyper-fine-structure effect. While the non-LTE effect tends to strengthen lines in G stars, it acts in the direction of line weakening in the regime of A stars due to increasing imortance of overionization. The Ba abundances of G stars turned out almost constant (<A>= 2.33), indicating that the primordial composition of Ba in Hyades is mildly supersolar by ~+0.2dex. In contrast, A-type stars show Ba overabundances of considerably large dispersion (0~<[Ba/H]~<2). Since this Ba excess tends to increase with an increase/decrease in Teff/vsini, these two parameters may be essential for producing or controling the anomaly. Regarding Hyades F-type stars, their Ba abundances are not uniform but show a broad depression (by <~0.3dex) around Teff~6500K, interestingly coinciding with the location of Li-dip. |
| title | Barium abundances of A--F--G type stars in the Hyades cluster |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2510.20546 |