The metal-poor end of the Spite plateau: gravity sensitivity of the Hα wings fitting.

We recently presented (Sbordone et al., 2009a) the largest sample to date of lithium abundances in extremely metal-poor (EMP) Halo dwarf and Turn-Off (TO) stars. One of the most crucial aspects in estimating Li abundances is the T_eff determination, since the Li I 670.8 nm doublet is highly temperature sensitive. In this short contribution we concentrate on the T_eff determination based on Hα wings fitting, and on its sensitivity to the chosen stellar gravity.