Preliminary results from the quantitative spectroscopic analysis of ≈500 O9–B6 type stars presented in this work for which the FW3414(Hβ) has been measured. The color code in both panels indicates the LC taken from Simbad. Left panel: sHRD for these stars and additional results from Holgado et al. (2018), indicated with gray dots. The evolutionary tracks are taken from the MESA Isochrones & Stellar Tracks online tool for solar metallicity and no initial rotation. The approximate separation between O- and B-type stars is indicated with the dotted diagonal black line. The dashed horizontal black line at log(ℒ/ℒ_⊙) = 3.5 dex used in the selection of the working sample is indicated (also shown in the right panel). Right panel: log(ℒ/ℒ_⊙) against FW3414(Hβ) for the same ≈500 stars. The vertical dashed red line shows the value we adopted to select the working sample. Open circles indicate stars with v sin i > 120 km s⁻¹, and gray crosses are SB2+ systems. Stars without luminosity classes in Simbad are plotted in pink.