Wednesday, 25 August at 2.00pm @ the JAC

  ABSTRACT: I will discuss a 2MASS study of 215 candidate massive protostars which include a sample of both pre-UCHII and UCHII phases. We have conducted a systematic study of clustering associated with these massive protostars which reveal 60 embedded clusters. However, the detection of these clusters do not show any significant addition to the low mass end of the Embedded Cluster Mass Distribution Function. The results indicate that massive star birth begins atleast about 0.5-1 million years after low mass star birth begins in these small groups/clusters. Color-color diagrams of near-infrared counterparts of millimeter peaks (associated with massive protostars) show color excess much more than that enclosed by the HAeBe curve. The excess emission is likely due to H2 line emission arising from other than outflow contribution. The proto-clusters associated with massive protostars appear to be simple and neat laboratories to study the formation of small-clusters. I will also discuss the detailed study of two peculiar ring shaped clusters discovered from the larger sample. Infrared and molecular line observations of these ring clusters show evidences for a flattenned structure associated with central cavities.