[Fe/H] vs. R_GC (upper panel) and R_GC vs. [α/Fe] (lower panel) in the chemical evolution model of Magrini et al. (2009). The three curves are the curve at present time (blue), ~5 Gyr ago (red) and ~10 Gyr ago (black). The green shaded area indicates where and when HAMR stars might be born, the black filled circles are the four open clusters and the yellow squares are the median values of the inner disc field stars in the metallicity range from −0.1 to +0.33 dex, whose [α/Fe] are computed removing the NLTE effects. Finally, the red triangles are the median values of the solar neighbourhood stars in the metallicity range from −0.1 to +0.33 dex.