CCD UBV photometry of the young open cluster NGC 3766

NGC 3766 is a young open cluster, located in the Carina complex, which contains an unusually large number of Be stars. This fact makes it specially interesting for providing observational constraints for the Be phenomenon. We have obtained UBV photometry for this cluster using a mosaic of CCD images centered around the cluster field, resulting in the deepest color-magnitude diagram of NGC 3766 obtained so far. The analysis of the photometric diagrams yielded a reddening of E(B-V)=0.20±0.10, a distance modulus of (m-M)0=11.73±0.33 and an age of about 24 Myr. The luminosity function was derived by using the photometry of a nearby star field to remove field contamination from the cluster sample. The slope of the mass function was found to be Γ=-1.41±0.08 in the range 2.5<M/M⊙<12.5, very close to the Salpeter value (ΓSalpeter=-1-35). There are some hints of mass segregation in this cluster. © 1997 American Astronomical Society.