2019MNRAS.483.3146B

We present the results from NH₃ mapping observations towards 34 regions identified by the Red MSX Source (RMS) survey. We have used the Australia Telescope Compact Array to map ammonia (1, 1) and (2, 2) inversion emission spectra at a resolution of 10 arcsec with velocity channel resolution of 0.4 km s^–1 towards the positions of embedded massive star formation. Complementary data have been used from the ATLASGAL and GLIMPSE Legacy Surveys in order to improve the understanding of the regions and to estimate physical parameters for the environments. The fields have typical masses of ∼1000 M_☉, radii of ∼0.15 pc, and distances of ∼3.5 kpc. Luminosities range between ∼10³ and ∼10⁶ L_☉ and kinetic temperatures between 10 and 40 K. We classify each field into one of two subsets in order to construct an evolutionary system for massive star formation in these regions based on the morphology and relative positions of the NH₃ emission, RMS sources, and ATLASGAL thermal dust emission. Differences in morphology between NH₃ emission and ATLASGAL clumps are shown to correspond to evolutionary stages of ongoing massive star formation in these regions. The study has been further refined by including the positions of known methanol and water masers in the regions to gain insight into possible protostellar regions and triggered star formation.