On the depletion of lithium in the Sun

We describe evolutionary sequences of solar models starting in a fully convective phase at the Hayashi line. An overshoot layer of ≃ 0.30 pressure scale heights is sufficient for the depletion of lithium by a factor 100. The destruction of Li occurs almost entirely during the pre-mam-sequence evolution, within a period of 1.5·10⁷ years when the star develops a radiative core and departs from the Hayashi line. For the present Sun, the same overshoot layer leads to a convection zone of ≃ 200000 km total depth, in good agreement with the helioseismic evidence and with the needs of the solar dynamo.