Molecular line mapping of the giant molecular cloud associated with RCW 106 II: column density and dynamical state of the clumps

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Title: Molecular line mapping of the giant molecular cloud associated with RCW 106 II: column density and dynamical state of the clumps
Author(s): Wong, Tony P. Y.; Ladd, E. F.; Brisbin, D.; Burton, Michael G.; Bains, I.; Cunningham, Maria R.; Lo, N.; Jones, Paul A.; Thomas, K. L.; Longmore, Steven N.; Vigan, A.; Mookerjea, B.; Kramer, Carsten; Fukui, Yasuo; Kawamura, Akiko
Abstract: We present a fully sampled C18O (1-0) map towards the southern giant molecular cloud (GMC) associated with the H ii region RCW 106, and use it in combination with previous 13CO (1-0) mapping to estimate the gas column density as a function of position and velocity. We find localized regions of significant 13CO 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 H ii region G333.6-0.2. Optical depth corrections broaden the distribution of column densities in the cloud, yielding a lognormal distribution as predicted by simulations of turbulence. Decomposing the 13CO and C18O 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.
Publication type: Journal article
Research centre: Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing
Source: Monthly Notices of the Royal Astronomical Society, Vol. 386, no. 2 (May 2008), pp. 1069-1084
Publication year: 2008
FOR Code(s): 0201 Astronomical and Space Sciences; 020104 Galactic Astronomy
Keyword(s): Clouds; ISM; Molecules; Stars formation; Structure
Publisher: Wiley-Blackwell Publishing
ISSN: 0035-8711
Publisher URL: http://dx.doi.org/10.1111/j.1365-2966.2008.13107.x
Peer reviewed