Lithium evolution and mixing mechanisms in open clusters
Paola Sestito (Dipartimento di Astronomia, Universita' di Firenze)
Sofia Randich (INAF/Osservatorio Astrofisico di Arcetri)
Lithium is a very good tracer of mixing processes occurring in stellar interiors, due to its relatively low burning temperature.
Open clusters (OCs) represent a natural testing ground for
investigating Li depletion as a function of age/mass/chemical composition. Studies of Li in OCs reveal several discrepancies between empirical evidence and theoretical predictions. Furthermore, the current observational scenario is likely to be affected by uncertainties due to different methods of analysis, and a complete picture of Li evolution in the age-mass-metallicity plane is not yet available. We report here a new homogeneous analysis of all the Li data for G and early-K stars in OCs of different ages and metallicities available in the literature: in this way, we have provided a completely unbiased database, putting all the clusters on the same scale of Li abundances and effective temperatures. Based on this revised set of abundances, we discuss the time scales of Li depletion in different age intervals and the dependence on metallicity.