Panel a)  [Fe/H]  distribution when slicing in absolute magnitude (M_VT) 5976 stars (grey circles) that belong to the irfm sample and are within the metallicity calibration range. Contour levels are computed on abscissa intervals of 0.1 mag to equally represent regions with fewer stars. Panel b) and c)  [Fe/H]  distribution of the same stars, but plotted as a function of distance and parallax error. In all panels, stars with M_VT < 2 are overplotted as black squares (271 in total).