Lithium abundance as a boundary condition for age and mass determination of solar twin stars

We explore the non-standard mixing history of five solar twins to determine as precisely as possible their mass and age. For this, we computed a grid of evolutionary models with non-standard mixing at given metallicities with the Toulouse-Geneva code for a range of stellar masses. We choose the evolutionary model that best fit the low lithium abundances observed in the solar twins. Our best model for each solar twin provides a mass and age solution constrained by their Li content and Teff determination. Li depletion due to the additional mixing in solar-twins is strongly mass dependent. An accurate lithium abundance measurement connected with non-standard models provides a more precise information about the age and mass better than that determined only by classical methods.