Fe Abundances in metal-poor stars

We present here VLT-UVES Li abundances for 28 halo dwarf stars between [Fe/H]=-2.5 and -3.5, 10 of which have [Fe/H]<-3. Four different Teff scales have been used: Direct Infrared Flux Method (IRFM) has been used on the basis of 2MASS infrared photometry; H{alpha} wings have been fitted against two synthetic grids computed by means of 1D LTE atmosphere models, and a grid of H{alpha} profiles computed by means of 3D hydrodynamical atmosphere models.

As a result, we confirm previous claims that A(Li) does not exhibit a plateau below [Fe/H]=-3. A strong positive correlation with [Fe/H] appears, not influenced by the choice of the Teff estimator. From a linear fit, we obtain a strong slope of about 0.30 dex in A(Li) per dex in [Fe/H], significant to 2-3, and consistent within 1 among all the four Teff estimators.