Results of the number of stars against their spectral type (two leftmost panels) and luminosity class (two rightmost panels), represented in histograms. Each bin stacks the number of stars with different morphologies found for the Hβ and Hα profiles following the classification in Sect. 3.2.1 and grouped as in the legend. Stars labeled within the “Absorption” label include profiles CF, DsP, PCy, and RF. The sources with LC I without subtype in the literature are grouped into a separate bin. The sources classified as SB2+ are removed from the bins.