Lithium depletion in G and K dwarfs

We have investigated the depletion of the surface Li abundance in low-mass main-sequence stars of 0.8-1.2 M⊙. We compare our evolutionary models with the observed Li abundances of G and K dwarfs in young open clusters (mainly the Pleiades and the Hyades clusters) and the Sun. Standard models with no mixing in the radiative zone give a N_Li-T_eff relation that roughly coincides with the relation for the lower envelope of the Pleiades. Standard models, however, give hardly any depletion of Li during the period between the Pleiades and Hyades ages. We have considered non-standard mixing in the radiative zone as a result of overshooting from the lower boundary of the convective envelope and rotationally induced slow turbulence. The overshooting depletes more Li in less-massive stars, while the rotational mixing affects Li depletion in a similar fashion over the entire mass range considered. We have found that reasonable agreement with observations is obtained if these types of mixing are included in the main-sequence evolution but suppressed in the pre-main-sequence phase.