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CNO and Li abundances in Barium-enriched stars

Published online by Cambridge University Press:  01 August 2006

Natalia A. Drake  and
Claudio B. Pereira
Natalia A. Drake
Affiliation:
Observatório Nacional/MCT, Rua José Cristino, 77, Rio de Janeiro 20921-400, Brazil email: [email protected], [email protected] Sobolev Astronomical Institute, St. Petersburg State University, Universitetski pr. 28, St. Petersburg 198504, Russia.
Claudio B. Pereira
Affiliation:
Observatório Nacional/MCT, Rua José Cristino, 77, Rio de Janeiro 20921-400, Brazil email: [email protected], [email protected]
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Abstract

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CNO and Li abundances and 12C/13C isotopic ratios have been derived for two metal-poor Ba giants, HD 104340 and HD 206983, and two CH subgiants, HD 50264 and HD 87080. High resolution spectra obtained with the 1.52 m telescope and the FEROS echelle spectrograph at ESO, La Silla, Chile, were used in this study. CNO and Li abundances so as 12C/13C isotopic ratios were determined by applying the synthetic spectrum method to the lines of C2, CH, CN, [O I’ and Li I. Our analysis showed that the giant stars studied here have quite different natures: HD 206983 is a metal-poor barium star while HD 104340, although showing enhancement of s-process elements, should not be considered as a classical barium star: its barium syndrome can be explained by internal nucleosynthesis. The low metallicity giant HD 104340 can experience deeper convective mixing and, consequently, a larger dredge-up of CNO-cycle products compared to normal red giants. Light element abundance pattern of HD 104340 resembles anomalies resulting from the appearance on the stellar surface of material enriched in triple-α and CNO cycling.

Keywords

Stars: chemically peculiarstars: abundancesstars: evolutionstars: individual (HD 50264, HD 87080, HD 104340, HD 206983)
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S239: Convection in Astrophysics , August 2006 , pp. 304 - 306
Copyright
Copyright © International Astronomical Union 2007

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