Publication: Lithium abundance and activity in a sample of RS Canum-Venaticorum and BY Draconis stars
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1993-07
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Abstract
Observations of the Li i doublet at 6707.8 angstrom for a sample of active binary systems RS CVn and By Dra have been carried out at the Calar Alto Observatory with the 2.2 m telescope. In addition, some single stars with different chromospheric activity levels have also been observed mainly for comparison purposes. Gaussian fits have been performed in order to separate the Fe I line at 6707.4 angstrom which is usually blended with the Li I doublet. Once the fit was achieved, the equivalent width was measured for each separated line. The contributions due to the continuum from both components have been taken into account to correct the equivalent width measurements. A curve-of-growth method has been used to derive lithium abundances. We have obtained a Li excess in the binary systems, in particular the K type stars. A correlation of the Li abundance with the activity levels is confirmed, as it was found by other authors, but RS CVn and BY Dra systems are 0.5 dex more active than single stars for the same Li abundance.
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© 1994 ESO. The authors acknowledge valuable discussion with and suggestion from Roberto Pallavicini. The Calar Alto Observatory is operated jointly the Max-Planck-Institut für Astronomie (Heidelberg) and the Spanish Comisión Nacional de Astronomía. We thank the Calar Alto staff for their help during the observations. This work has been supported in part by the Universidad Complutense de Madrid.