Deep near-infrared imaging toward the Vela Molecular Ridge C. I. A remarkable embedded cluster in RCW 36

We present deep near-infrared (J, H, and K(s)) images toward an embedded cluster that lies in a C(18)O clump in cloud C of the Vela Molecular Ridge. This cluster has at least similar to350 members and a radius of similar to0.5 pc. The stellar surface number density is approximately 3000 stars pc(-2) in the central 0.1 x 0.1 pc region of the cluster. This is much higher than most of the young clusters within 1 kpc of the Sun. From a comparison of the luminosity function and near-infrared excess fraction with those of other embedded clusters, we estimate that the age of this cluster is approximately 2-3 Myr. This cluster exhibits an excess of brighter stars in its central region, from which we conclude that the more massive stars are located near the cluster center.