SURVIVAL OF Li AND Li IN METAL-POOR STARS

The relationship between the depletions of Li and Li is studied for two models of lithium burning, below the convective zone. The parameters of the depletion models are submitted to the constraint that the slope of the Li theoretical depletion curve agrees with the slope of the observed depletion curve, for cool subdwarfs. Other less restrictive models are also considered. In all cases, a Li depletion less than 0.5 dex implies a Li depletion less than 0.1 dex. With the constraint on the slope of the Li curve, the depletion of Li for the same depletion of Li is below 0.05 dex. The still unsolved problem for the true Li abundance in subdwarfs is the possible influence of temperature inhomogeneities, raised by Kurucz, subsequently shown to be small in the solar case, but not yet computed with the inclusion of departure from LTE for metal-poor stars.