1. Atmospheric chemical composition of the peculiar carbon giant TU Gem
- Author
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M. K. Kuznetsov, Ya. V. Pavlenko, L. A. Yakovina, and G. A. Polinovskii
- Subjects
Physics ,010504 meteorology & atmospheric sciences ,Metallicity ,Analytical chemistry ,chemistry.chemical_element ,Astronomy and Astrophysics ,Astrophysics ,01 natural sciences ,Atmosphere ,chemistry ,Space and Planetary Science ,0103 physical sciences ,CH star ,Lithium ,Halo ,010303 astronomy & astrophysics ,Chemical composition ,Carbon ,0105 earth and related environmental sciences - Abstract
The evolutionary status of the bright peculiar carbon giant TU Gemis fairly uncertain. The possibility that this is aCH star—aGalactic halo star with characteristic chemical-composition anomalies—is considered. Unfortunately, data on the atmospheric chemical composition of TUGem are relatively few and are ambiguous. The results of an analysis of a moderate-resolution optical and near-infrared spectrum of TU Gem obtained on the 2-m telescope of Terskol Peak Observatory (Northern Caucasus) is presented. The atmospheric parameters of TU Gem T eff = 3100 K, C/O = 1.10, and [N/Fe] = 0.0 for the derived metallicity [Fe/H] = 0.0 are taken from [1]. The abundances of Na, Mg, Ca, Ti, and Cr are estimated to be normal or slightly enhanced, and the lithium abundance is log N(Li) = +0.1. The abundances of s-process elements are substantially enhanced in the atmosphere of TU Gem, namely, [s/Fe] ≈ 2, for both light and heavy s-process elements. The range of uncertainty in [Fe/H] is 0.0−0.3, and the uncertainties in other estimates are Δ[M/Fe]≈ ±0.3 and Δ[s/Fe] = ±0.5. The results show that TU Gem is an anomalous carbon giant, but not a CH star.
- Published
- 2017
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