12C/13C ratios and Li abundances in C stars: evidence for deep mixing?
Open Access
- 21 August 1997
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 289 (4) , L11-L15
- https://doi.org/10.1093/mnras/289.4.L11
Abstract
High-resolution spectra are used to derive Li abundances and 12C/13C ratios for 44 Galactic C stars. It is found that Li-rich stars [log € (Li) > 1] usually have low 12C/13C ratios ( < 15). The great majority of the Li-rich and low 12C/13C stars are of J type, although this correlation can also be found in normal (N-type) C stars. If these stars were indeed low-mass C stars, these results would require the existence of a deep- mixing mechanism able to operate in low-mass (M≲ 2 M⊙) C stars as an alternative for Li production by the hot bottom burning mechanism proposed in asymptotic giant branch stars with larger mass. We show observational evidence suggesting that high mass loss appears to act against such a mechanism.Keywords
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