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 Ks) images toward an embedded cluster that lies in a C18O clump in cloud C of the Vela Molecular Ridge. This cluster has at least ~350 members and a radius of ~0.5 pc. The stellar surface number density is approximately 3000 stars pc-2 in the central 0.1 × 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.

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