Binarity at LOw Metallicity (BLOeM): pipeline-determined physical properties of OB stars

We aim to determine the physical properties of OB stars from the multi-epoch Binarity at LOw Metallicity (BLOeM) spectroscopic surv e y of the Small Magellanic Cloud using the Very Large Telescope/Fibre Large Array Multi-Element Spectrograph. We apply a pipeline designed to analyse large spectroscopic samples of OB stars to the co-added, initial nine epochs of the BLOeM surv e y, 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 T eff , log g, log L/ L , and e sin i. There appears to be a bimodality in e sin i of single O stars, while e sin i distributions of OB stars are strikingly different for single (median 78 km s −1 ) and binary (median 200 km s −1 ) 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. Rotational velocities are broadly in line with an independent tool applied to the same subset. We reco v er the anticipated lower mass cut-off at 8 M from the surv e y design using a Bayesian inference method coupled with SMC metallicity evolutionary models, with median masses of 12.6 M (19.8 M ) for B-type (O-type) stars. Spectroscopic masses exceed evolutionary masses, albeit with large uncertainties in surface gravities. We also provide an updated catalogue of O stars in the SMC since half of the 159 BLOeM O stars are newly classified as O-type stars.