Spectroscopic sample of Galactic O9-B9 SGs

We show the benefits of the proposed strategy for identifying BSGs descending, in the context of single star evolution, from stellar objects born as O-type stars. The resulting sample reaches a high level of completeness with respect to the ALS III catalog, gathering ~80% of all-sky targets brighter than Bmag<9 located within 2kpc. However, we identify the need for new observations in specific regions of the Southern hemisphere.

We have explored a very fast and robust method to select BSGs, providing a valuable tool for large spectroscopic surveys as WEAVE-SCIP or 4MIDABLE-LR, and highlighting the risk of using spectral classifications from the literature. Upcoming studies will make use of this large and homogeneous spectroscopic sample to study specific properties of these stars in detail. We initially provide first results about their rotational properties (in terms of projected rotational velocities, vsini)