SpT–T_eff (middle panels) and SpT–log g (bottom panels) calibrations. The global sample is divided by luminosity class groups in columns. Top panels: the number of stars per spectral type bin. The “observational scales” proposed by MSH05 are indicated by dashed lines. Calibrations obtained in this work are solid lines. As in previous figures, open symbols indicate stars for which we have detected clear or likely signatures of spectroscopic binarity. Stars with luminosity class Ia are not considered for the calibrations presented inTable 5, and as solid lines in these figures.