A Gaia Survey for Young Stars Associated with the Lupus Clouds*

Abstract

I have used high-precision photometry and astrometry from the second data release of the Gaia mission to perform a survey for young stars associated with the Lupus clouds, which have distances of ∼160 pc and reside within the Scorpius-Centaurus (Sco-Cen) OB association. The Gaia data have made it possible to distinguish Lupus members from most of the stars in other groups in Sco-Cen that overlap with the Lupus clouds, which have contaminated previous surveys. The new catalog of candidate Lupus members should be complete for spectral types earlier than M7 at A K  < 0.2 within fields encompassing clouds 1–4. I have used that catalog to characterize various aspects of the Lupus stellar population. For instance, the sequence of low-mass stars in Lupus is ∼0.4 mag brighter than the sequence for Upper Sco, which implies an age of ∼6 Myr based an adopted age of 10–12 Myr for Upper Sco and the change in luminosity with age predicted by evolutionary models. I also find that the initial mass function in Lupus is similar to that in other nearby star-forming regions based on a comparison of their distributions of spectral types.