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