BLOeM. Physical properties of OB stars

We apply a pipeline designed to analyse large spectroscopic samples of OB stars to the co-added, initial nine epochs of the BLOeM survey, utilizing grids of synthetic model spectra computed with the stellar atmosphere code fastwind. 69 OB stars are excluded from the analysis owing to disc emission or significant contamination by secondaries in SB2 binaries.

We determine physical properties of 778 OB stars, including Teff, logg, logL_{sun}_, and v_e_*sini. There appears to be a bimodality in v_e_*sini of single O stars, while v_e_*sini distributions of OB stars are strikingly different for single (median 78km/s) and binary (median 200km/s) systems. Inferred temperatures are broadly in agreement with literature results for stars in common, plus results from a grid-based automization tool for a subset of O and early B stars, although uncertainties are larger for surface gravities.