2012A&A...541A.150P

Lithium abundances in open clusters are a very effective probe of mixing processes, and their study can help us to understand the large depletion of lithium that occurs in the Sun. Owing to its age and metallicity, the open cluster M 67 is especially interesting on this respect. Many studies of lithium abundances in M 67 have been performed, but a homogeneous global analysis of lithium in stars from subsolar masses and extending to the most massive members, has yet to be accomplished for a large sample based on high-quality spectra. We test our non-standard models, which were calibrated using the Sun with observational data. We collect literature data to analyze, for the first time in a homogeneous way, the non-local thermal equilibrium lithium abundances of all observed single stars in M 67 more massive than ∼0.9M_☉. Our grid of evolutionary models is computed assuming a non-standard mixing at metallicity [Fe/H]=0.01, using the Toulouse-Geneva evolution code. Our analysis starts from the entrance into the zero-age main-sequence. Lithium in M 67 is a tight function of mass for stars more massive than the Sun, apart from a few outliers. A plateau in lithium abundances is observed for turn-off stars. Both less massive (M≤1.10M_☉) and more massive (M≥1.28M_☉) stars are more depleted than those in the plateau. There is a significant scatter in lithium abundances for any given mass