Lithium abundances for early F stars: new observational constraints for the Li dilution

¹ UMR 5024 CNRS/UMII, Université Montpellier II, CC 72, 34095 Montpellier Cedex 5, France
² Observatoire de la Côte d'Azur, Département Cassiopée, UMR 6202, BP 4229, 06304 Nice Cedex 04, France
³ Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India
⁴ Departamento de Física, Universidade Federal do Rio Grande do Norte, Campus Universitário, 59072-970 Natal, RN, Brazil e-mail: renan@dfte.ufrn.br

Received: 26 October 2005
Accepted: 28 February 2006

Abstract

Aims.To investigate any correlation between Li abundances and rotational velocities among F–G evolved stars, we study a large sample of early F stars from the Bright Star Catalogue (BSC), most of them classified in the literature as giant stars.

Methods.Physical parameters and Li abundances are estimated for each star, often for the first time, by comparing observed and synthetic spectra. We analyse the position of the stars in the H–R Diagram based on Hipparcos data using stellar evolutionary tracks and we discuss their Li abundances and projected rotational velocities.

Results.Observed stars are mostly on the turnoff, with masses between 1.5 and . The stars with measured A(Li) abundance show high Li content, most of them with abundance near the cosmic value. The A(Li) versus diagram shows the same trend as reported in previous studies: fast rotators ( km s^-1) are also stars with high Li content, whereas slow rotators present a wide range of values of A(Li), ranging from no detected Li to the cosmic value.