Molecular line mapping of the giant molecular cloud associated with RCW 106 - II. Column density and dynamical state of the clumps

Abstract

We present a fully sampled C^{18}O (1-0) map towards the southern giant molecular cloud (GMC) associated with the HII region RCW 106, and use it in combination with previous ^{13}CO (1-0) mapping to estimate the gas column density as a function of position and velocity. We find localized regions of significant ^{13}CO optical depth in the northern part of the cloud, with several of the high-opacity clouds in this region likely associated with a limb-brightened shell around the HII region G333.6-0.2. Optical depth corrections broaden the distribution of column densities in the cloud, yielding a log-normal distribution as predicted by simulations of turbulence. Decomposing the ^{13}CO and C^{18}O data cubes into clumps, we find relatively weak correlations between size and linewidth, and a more sensitive dependence of luminosity on size than would be predicted by a constant average column density. The clump mass spectrum has a slope near -1.7, consistent with previous studies. The most massive clumps appear to have gravitational binding energies well in excess of virial equilibrium; we discuss possible explanations, which include magnetic support and neglect of time-varying surface terms in the virial theorem. Unlike molecular clouds as a whole, the clumps within the RCW 106 GMC, while elongated, appear to show random orientations with respect to the Galactic plane.

arXiv comment17 pages, to appear in MNRAS

References in corpus (21)

• Density, Velocity, and Magnetic Field Structure in Turbulent Molecular Cloud Models
• Dissipation in Compressible MHD Turbulence
• The Universality of the Stellar IMF
• Infrared Dark Clouds: precursors to star clusters
• Velocity Modification of HI Power Spectrum
• Density probability distribution in one-dimensional polytropic gas dynamics
• Bias-free Measurement of Giant Molecular Cloud Properties
• The Equilibrium State of Molecular Regions in the Outer Galaxy
• The COMPLETE Survey of Star-Forming Regions: Phase I Data
• 2MASS wide field extinction maps - I. The Pipe nebula
• Physical vs. Observational Properties of Clouds in Turbulent Molecular Cloud Models
• The Probability Distribution Function of Column Density in Molecular Clouds
• Southern Galactic Plane Survey Measurements of the Spatial Power Spectrum of Interstellar H I in the Inner Galaxy
• Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes, Alignment and Rotation
• The Virial Balance of Clumps and Cores in Molecular Clouds
• Interstellar Turbulence: II. Energy Spectra of Molecular Regions in the Outer Galaxy
• The Shapes of Dense Cores and Bok Globules
• The Giant Molecular Cloud associated with RCW 106 -- A 1.2 mm continuum mapping study
• The Elongations and Supersonic Motions of Molecular Clouds
• High Mass Star Formation. III. The Functional Form of the Submillimeter Clump Mass Function
• Prolate Cores in Filamentary Molecular Clouds

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• The Three-mm Ultimate Mopra Milky Way Survey. II. Cloud and Star Formation Near the Filamentary Ministarburst RCW 106
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