تقرير
Element abundances of galactic RGB stars in the APO-K2 catalogue. Dissimilarity in the scaling with [$\alpha$/Fe]
| العنوان: | Element abundances of galactic RGB stars in the APO-K2 catalogue. Dissimilarity in the scaling with [$\alpha$/Fe] |
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| المؤلفون: | Valle, G., Dell'Omodarme, M., Moroni, P. G. Prada, Degl'Innocenti, S. |
| سنة النشر: | 2024 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies, Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | We conducted an investigation on the chemical abundances of 4,316 stars in the red giant branch (RGB) phase from the recently released APO-K2 catalogue. Our aim was to characterize the abundance trends of the single elements with [$\alpha$/Fe], mainly focusing on C, N, and O, which are the most relevant for the estimation of stellar ages. The chemical analysis of the RGB sample involved cross-matching data from the APO-K2 catalogue with individual element abundances from APOGEE DR17. The analysis detected a statistically significant difference in the [(C+N+O)/Fe] - [$\alpha$/Fe] trend with respect to the simple $\alpha$-enhancement scenario. This difference remained robust across different choices for the reference solar mixture and potential zero-point calibrations of C and N abundances. The primary discrepancy was a steeper increase in [O/Fe] with [$\alpha$/Fe], reaching a 0.1 dex difference at [$\alpha$/Fe] = 0.3. Notably, the impact on the evolutionary timescale of such oxygen over-abundance with respect to the commonly adopted uniform $\alpha$-enhancement is rather limited. We verified that stellar models computed using an ad hoc O-rich mixture sped up the evolution by only 1% at [$\alpha$/Fe] = 0.3, due to the counterbalancing effects of O enrichment on both the evolutionary timescale and the Z-to-[Fe/H] relationship. Comment: Accepted for publication in A&A |
| نوع الوثيقة: | Working Paper |
| URL الوصول: | http://arxiv.org/abs/2407.05960 |
| رقم الأكسشن: | edsarx.2407.05960 |
| قاعدة البيانات: | arXiv |
| الوصف غير متاح. |