Panel a) αFe for stars in the irfm sample having V_LSR = V + V_⊙ > 20   km   s^-1 (filled diamonds) or < −40   km   s^-1 (open circles). Only  [Fe/H]  >  −0.73 dex were selected to avoid a metal-poor tail in stars with negative velocities (the cut in  [Fe/H]  was selected to be the same as the lower-most value encountered in stars having V_LSR > 20   km   s^-1, but its exact choice is anyway irrelevant for the discussion). A few stars with clear halo kinematics were also excluded. Lower/upper continuous line connects the mean αFe in different  [Fe/H]  intervals for filled diamonds/open circles. Error bars (slightly offset in abscissa for clearer comparison) are the standard deviation of the mean in each  [Fe/H]  bin. Panel b) V_LSR as function of metallicity for all stars in sample irfm with kinematic information. Filled diamonds and open circles as in the previous panel. Panels c) and d) normalized metallicity and age distributions for the two previous group of stars having V_LSR > 20   km   s^-1 (continuous line) or < − 40   km   s^-1 (dashed line). The value V_⊙ = 12.24km   s^-1 was adopted (Schönrich et al. 2010).