Scaled up low-mass star formation in massive star-forming cores in the
  G333 giant molecular cloud
  Three bright molecular line sources in G333 have recently been shown to
exhibit signatures of infall. We describe a molecular line radiative transfer
modelling process which is required to extract the infall signature from Mopra
and Nanten2 data. The observed line profiles differ greatly between individual
sources but are reproduced well by variations upon a common unified model where
the outflow viewing angle is the most significant difference between the
sources. The models and data together suggest that the observed properties of
the high-mass star-forming regions such as infall, turbulence, and mass are
consistent with scaled-up versions of the low-mass case with turbulent
velocities that are supersonic and an order of magnitude larger than those
found in low-mass star-forming regions. Using detailed radiative transfer
modeling, we show that the G333 cores are essentially undergoing a scaled-up
version of low mass star formation. This is an extension of earlier work in
that the degree of infall and the chemical abundances are constrained by the RT
modeling in a way that is not practical with a standard analysis of
observational data. We also find high velocity infall and high infall mass
rates, possibly suggesting accelerated collapse due to external pressure.
Molecular depletion due to freeze-out onto dust grains in central regions of
the cores is suggested by low molecular abundances of several species. Strong
evidence for a local enhancement of 13C-bearing species towards the outflow
cloud cores is discussed, consistent with the presence of shocks caused by the
supersonic motions within them.
