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Yoichi Takeda, Satoshi Honda, Takashi Ohnishi, Michiko Ohkubo, Ryuko Hirata, Kozo Sadakane, Lithium, Carbon, and Oxygen Abundances of Hyades F–G Type Stars, Publications of the Astronomical Society of Japan, Volume 65, Issue 3, 25 June 2013, 53, https://doi.org/10.1093/pasj/65.3.53
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Abstract
In an attempt to carry out a systematic study on the behavior of the photospheric abundances of Li, C, and O (along with Fe) for Hyades main-sequence stars in the |$ T_{\rm eff}$| range of |$ \sim$| 5000–7000 K, we conducted an extensive spectrum-synthesis analysis applied to four spectral regions (comprising lines of Fe-group elements, Li I 6708 line, C I 7111–7119 lines, and O I 6156–8 lines), based on the high-dispersion spectra of 68 selected F–G type stars belonging to this cluster. The abundances of C and O turned out to be fairly uniform in a marginally supersolar level, such as like the case of Fe: |$ \langle$| [C|$ /$| H]|$ \rangle$||$ =$||$ +$| 0.15 (|$ \sigma$||$ =$| 0.08), |$ \langle$| [O|$ /$| H]|$ \rangle$||$ =$||$ +$| 0.22 (|$ \sigma$||$ =$| 0.14), and |$ \langle$| [Fe|$ /$| H]|$ \rangle$||$ =$||$ +$| 0.11 (|$ \sigma$||$ =$| 0.08), suggesting that the primordial abundances are almost retained for these elements. Strictly, however, they show a slightly increasing trend with a decrease in |$ T_{\rm eff}$| (typically on the order of |$ \sim$| 10|$ ^{-4}$| dex K|$ ^{-1}$| ); while this might be due to an improper choice of atmospheric parameters, we found it difficult to give a quantitatively reasonable explanation. Regarding Li, we confirmed the well-known |$ T_{\rm eff}$|-dependent trend in the Li abundance reported so far (a conspicuous Li-trough at 6300 K |$ ≲$||$ T_{\rm eff}$||$ ≲$| 6700 K and a progressive decrease toward a lower |$ T_{\rm eff}$| at |$ T_{\rm eff}$||$ ≲$| 6000 K), which means that the surface Li of Hyades stars is essentially controlled only by |$ T_{\rm eff}$| ; other parameters, such as the rotational velocity, are almost irrelevant.
