The newly hatched rich massive cluster in the ridge of the rosette molecular cloud

We explore loose congregations of medium- to high-mass protoclusters identified to the southeast of NGC 2244. On using data from the spatially complete Two Micron All Sky Survey, the true extent of the burst of cluster formation along the ridge of the Rosette Molecular Cloud is revealed. Here we investigate the properties and fine structures of the most prominent cluster embedded in the densest rim of the cloud. This protocluster is resolved into two compact subclusters aligned along the major axis of the entire complex, in line with NGC 2244. The subclusters are found to have a physical scale of around 1 pc, typical of known embedded clusters. The K-band luminosity function also suggests a young age. However, near-infrared excess emission is found in approximately one-sixth of the reddened objects. This is still commensurate with an age estimate of < 1 Myr, provided that the massive stars have rapidly stripped the circumstellar material from their neighbors. The well-known massive young binary associated with AFGL 961, however, is situated to the south of the major components of the cluster, where the stellar density is comparatively low. This is inconsistent with mass segregation and signifies a different formation process for these high-mass protostellar objects.