Multiseeded Multimode Formation of Embedded Clusters in the Rosette Molecular Complex: Structured Star Formation toward the Southeastern Boundary

The Rosette Molecular Complex contains embedded clusters with diverseproperties and origins. We have previously explored the shell mode of formationin the north (Regions A & B) and the massive concentrations in the ridge(Region C). Here, we explore star formation towards the south of the complex,Region D, based on data from the spatially complete 2 Micron All Sky Survey. Wefind that stars are forming prolifically throughout this region in a highlystructured mode with both clusters and loose aggregates detected. The mostprominent cluster (Region D1) lies in the north-center. This cluster is over 20pc to the south of the Monoceros ridge, the interface of the emerging young OBcluster NGC 2244 with its ambient molecular clouds. In addition, there areseveral branches stemming from AFGL 961 in Region C and extending to thesouth-east boundary of the cloud. We invoke a tree model to interpret thispattern, corresponding to probable tracks of abrupt turbulent excitation andsubsequent decay. Alternatively, we discuss gravoturbulent collapse scenariosbased on numerical simulations. Relative stellar ages and gas flow directionswill differentiate between these mechanisms.Comment: 9 figures, the 4th of a series of paper