Revised magnesium abundances in galactic halo and disk stars

A differential analysis of the magnesium abundances in 61 F-K dwarfs and subgiants with metallicities ?2.6T _eff from V-K and V-R; logg from HIPPARCOS parallaxes, and Fe/H] and ξ_t from Fe II lines. The computations allow for non-LTE effects in the formation of the Mg I lines. For most of the stars, the standard errors in the Mg abundances do not exceed 0.07 dex. The metallicity dependence of Mg/Fe] is analyzed. Magnesium shows a constant overabundance relative to Fe of 0.46±0.06 dex for metallicities ?2.6 $\overline {Mg/Fe]} = + 0.22 dex$ ) compared to the Mg/Fe] values for other stars with similar Fe/H].