Physical characterization of southern massive star-forming regions using Parkes NH3 observations

Abstract

We have undertaken a Parkes ammonia spectral line study, in the lowest two inversion transitions, of southern massive star formation regions, including young massive candidate protostars, with the aim of characterizing the earliest stages of massive star formation. 138 sources from the submillimetre continuum emission studies of Hill et al. were found to have robust (1,1) detections, including two sources with two velocity components, and 102 in the (2,2) transition.We determine the ammonia line properties of the sources: linewidth, flux density, kinetic temperature, NH3 column density and opacity, and revisit our spectral energy distribution modelling procedure to derive the mass for 52 of the sources. By combining the continuum emission information with ammonia observations we substantially constrain the physical properties of the high-mass clumps. There is clear complementarity between ammonia and continuum observations for derivations of physical parameters.The MM-only class, identified in the continuum studies of Hill et al., displays smaller sizes, mass and velocity dispersion and/or turbulence than star-forming clumps, suggesting a quiescent prestellar stage and/or the formation of less massive stars. © 2010 The Authors. Journal compilation © 2010 RAS.