Lithium abundances and rotational behavior for bright giant stars

¹ Groupe de Recherche en Astronomie et Astrophysique du Languedoc, UMR 5024/ISTEEM (CNRS), Université de Montpellier II, Place Bataillon, 34095 Montpellier, France e-mail: lebre@graal.univ-montp2.fr
² Observatoire de la Côte d'Azur, Département Cassiopée, UMR 6202 (CNRS), BP 4229, 06304 Nice, France
³ Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN, Brazil

Received: 20 May 2005
Accepted: 16 November 2005

Abstract

Aims.We study the links possibly existing between the lithium content of bright giant stars and their rotational velocity.

Methods.We performed a spectral analysis of 145 bright giant stars (luminosity class II) spanning the spectral range from F3 to K5. All these stars have homogeneous rotational velocity measurements available in the literature.

Results.For all the stars of the sample, we provide consistent lithium abundances (A_Li), effective temperatures (T_eff), projected rotational velocity (), mean metallicity ([Fe/H]), stellar mass, and an indication of the stellar multiplicity. The gradual decrease in lithium abundance with T_eff is confirmed for bright giant stars, and it points to a dilution factor that is at least as significant as in giant stars. From the F to K spectral types, the A_Li spans at least three orders of magnitude, reflecting the effects of stellar mass and evolution on dilution.

Conclusions.We find that the behavior of A_Li as a function of   in bright giant stars presents the same trend as is observed in giants and subgiants: stars with high A_Li are moderate or fast rotators, while stars with low A_Li show a wide range of   values.