Empirical constraints are master keys for testing theoretical evolutionary model predictions. In massive stars, the region in the Hertzsprung-Russell diagram (HRD) in which the Blue Supergiants (BSGs) are located sets several important constraints to the models, and in particular to the theoretical end of the main sequence (MS). So far, we are

We present results from a recent study of the spin rate properties of a sample of more than 400 Galactic O-type stars surveyed by the IACOB and OWN projects. We combine vsini, Teff, and logg estimates with information about the spectroscopic binarity status for 285 of the stars in the sample, and provide a renewed overview about how the empirical

The Gaia-ESO Survey (GES) is a large public spectroscopic survey that has collected spectra of about 100,000 stars. The survey provides not only the reduced spectra, but also the radial velocities, stellar parameters and surface abundances resulting from the analysis of the spectra. We present the work of the groups that analysed the spectra of the