تقرير
WIYN Open Cluster Study, LXXVI. Li Evolution Among Stars of Low/Intermediate Mass: The Metal-Deficient Open Cluster, NGC 2506
| العنوان: | WIYN Open Cluster Study, LXXVI. Li Evolution Among Stars of Low/Intermediate Mass: The Metal-Deficient Open Cluster, NGC 2506 |
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| المؤلفون: | Anthony-Twarog, B. J., Lee-Brown, D. B., Deliyannis, C. P., Twarog, B. A. |
| سنة النشر: | 2018 |
| المجموعة: | Astrophysics |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics |
| الوصف: | HYDRA spectra of 287 stars in the field of NGC 2506 from the turnoff through the giant branch are analyzed. With previous data, 22 are identified as probable binaries; 90 more are classified as potential non-members. Spectroscopic analyses of ~60 red giants and slowly rotating turnoff stars using line equivalent widths and a neural network approach lead to [Fe/H] = -0.27 +/- 0.07 (s.d.) and [Fe/H] = -0.27 +/- 0.06 (s.d.), respectively. Li abundances are derived for 145 probable single-star members, 44 being upper limits. Among turnoff stars outside the Li-dip, A(Li) = 3.04 +/- 0.16 (s.d.), with no trend with color, luminosity, or rotation speed. Evolving from the turnoff across the subgiant branch, there is a well-delineated decline to A(Li) ~1.25 at the giant branch base, coupled with the rotational spindown from between ~20 and 70 km/s to less than 20 km/s for stars entering the subgiant branch and beyond. A(Li) remains effectively constant from the giant branch base to the red giant clump level. A new member above the clump redefines the path of the first-ascent red giant branch; its Li is 0.6 dex below the first-ascent red giants. With one exception, all post-He-flash stars have upper limits to A(Li), at or below the level of the brightest first-ascent red giant. The patterns are in excellent qualitative agreement with the model predictions for low/intermediate-mass stars which undergo rotation-induced mixing at the turnoff and subgiant branch, first dredge-up, and thermohaline mixing beyond the red giant bump. Comment: 30 pages, 9 figures, 4 tables. Accepted for Astronomical Journal |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-3881/aaad66 |
| URL الوصول: | http://arxiv.org/abs/1802.03447 |
| رقم الأكسشن: | edsarx.1802.03447 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-3881/aaad66 |
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