Lithium abundance in field K and M dwarfs

Abstract

It is widely accepted that lithium abundance in late-type stars correlates with other stellar characteristics, such as age, chromospheric activity and rotation. for example, the post-main-sequence active components of RS CVn binaries have been compared with inactive field stars of the same spectral type and found to have excess lithium. In stars with deep convective zones lithium is expected to be destroyed in a relatively short time. This is most dramatically true in the main-sequence stars of the latest type. In this paper we have examined the lithium abundances in a sample of late-K and M-type dwarfs. High signal-to-noise ratio, high spectral resolution spectra have been obtained of the Li i resonance doublet (λ,6707.8 Å,). Evidence for an appreciable lithium abundance has been found in stars as late as early to mid-M. Furthermore, there is evidence for a correlation between this Li abundance and chromospheric activity in the case of K dwarfs while M dwarfs do not appear to follow such a relation.