Physical characterisation of southern massive star-forming regions using Parkes NH${}_3$ 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 characterising 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, NH${}_3$ column density and opacity, and revisit our SED 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., display 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.

20 pages, 9 Figures, 1 appendix (to appear in full online only, a sample appendix in the paper); 7 tables. Accepted by MNRAS

References in corpus (5)

• Multi-wavelength observations of Southern Hot Molecular Cores traced by methanol masers - I. Ammonia and 24 GHz Continuum Data
• Millimetre Continuum Observations of Southern Massive Star Formation Regions II. SCUBA observations of cold cores and the dust grain emissivity index $\beta$
• Mid-Infrared Source Multiplicity within Hot Molecular Cores traced by Methanol Masers
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• Balloon-Borne Submillimeter Polarimetry of the Vela C Molecular Cloud: Systematic Dependence of Polarization Fraction on Column Density and Local Polarization-Angle Dispersion
• The H2O southern Galactic Plane Survey(HOPS): NH3 (1,1) and (2,2) catalogues
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• The M16 molecular complex under the influence of NGC6611. Herschel's perspective of the heating effect on the Eagle Nebula
• Large scale IRAM 30m CO-observations in the giant molecular cloud complex W43
• A Water Maser and Ammonia Survey of GLIMPSE Extended Green Objects (EGOs)
• Properties of Starless and Prestellar Cores in Taurus Revealed by Herschel SPIRE/PACS Imaging
• The fragmentation and stability of hierarchical structure in Serpens South
• H2O Southern Galactic Plane Survey (HOPS): Paper III - Properties of Dense Molecular Gas across the Inner Milky Way
• Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey
• Galactic interstellar sulfur isotopes: A radial ${}^{32}$S$/$${}^{34}$S gradient?
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• A Systematic Observational Study on Galactic Interstellar Ratio 18O/17O. II. C18O and C17O J=2-1 Data Analysis
• The TMRT K Band Observations towards 26 Infrared Dark Clouds: NH${}_3$, CCS, and HC${}_3$N