Four Highly Luminous Massive Star Forming Regions in the Norma Spiral Arm II. Deep NIR imaging

Abstract

We present sensitive NIR (J, H and K) imaging observations toward four luminous massive star forming regions in the Norma Spiral Arm: G324.201+0.119, G328.307+0.432, G329.337+0.147 and G330.949-0.174. We identify three clusters of young stellar objects (YSO) based on surface density diagnostics. We also find that sources detected only in the H and K-bands and with colors corresponding to spectral types earlier than B2, are likely YSOs. We analyze the spatial distribution of stars of different masses and find signatures in two clusters of primordial mass segregation which can't be explained as due to incompleteness effects. We show that dynamic interactions of cluster members with the dense gas from the parent core can explain the observed mass segregation, indicating that the gas plays an important role in the dynamics of young clusters.

Submitted to ApJ in September 2009

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• Dynamical Friction in a Gas: The Supersonic Case
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• The young stellar cluster [DBS2003] 157 associated with the H II region GAL 331.31-00.34
• The role of gas dynamical friction in the evolution of embedded stellar clusters
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