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Physical properties of giant molecular clouds in the Large Magellanic Cloud

Hughes, A. and Wong, T. and Ott, J. and Muller, E. and Pineda, J. L. and Mizuno, Y and Bernard, J.-P. and Paradis, D. and Maddison, S. and Reach, W. T. and Staveley-Smith, L. and Kawamura, A. and Meixner, M. and Kim, S. and Onishi, T. and Mizuno, N. and Fukui, Y. (2010) Physical properties of giant molecular clouds in the Large Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 406 (3). pp. 2065-2086. ISSN 0035-8711.

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The Magellanic Mopra Assessment (MAGMA) is a high angular resolution ^(12)CO (J = 1 → 0) mapping survey of giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud using the Mopra Telescope. Here we report on the basic physical properties of 125 GMCs in the LMC that have been surveyed to date. The observed clouds exhibit scaling relations that are similar to those determined for Galactic GMCs, although LMC clouds have narrower linewidths and lower CO luminosities than Galactic clouds of a similar size. The average mass surface density of the LMC clouds is 50 M_⊙ pc^(−2), approximately half that of GMCs in the inner Milky Way. We compare the properties of GMCs with and without signs of massive star formation, finding that non-star-forming GMCs have lower peak CO brightness than star-forming GMCs. We compare the properties of GMCs with estimates for local interstellar conditions: specifically, we investigate the H i column density, radiation field, stellar mass surface density and the external pressure. Very few cloud properties demonstrate a clear dependence on the environment; the exceptions are significant positive correlations between (i) the H i column density and the GMC velocity dispersion, (ii) the stellar mass surface density and the average peak CO brightness and (iii) the stellar mass surface density and the CO surface brightness. The molecular mass surface density of GMCs without signs of massive star formation shows no dependence on the local radiation field, which is inconsistent with the photoionization-regulated star formation theory proposed by McKee. We find some evidence that the mass surface density of the MAGMA clouds increases with the interstellar pressure, as proposed by Elmegreen, but the detailed predictions of this model are not fulfilled once estimates for the local radiation field, metallicity and GMC envelope mass are taken into account.

Item Type:Article
Related URLs:
URLURL TypeDescription
Ott, J.0000-0001-8224-1956
Pineda, J. L.0000-0001-8898-2800
Reach, W. T.0000-0001-8362-4094
Additional Information:© 2010 The Authors. Journal compilation © 2010 RAS. Accepted 2010 April 9. Received 2010 April 8; in original form 2010 January 25. Article first published online: 7 June 2010. We thank Christian Henkel, Jonathan Seale and MinWang for their assistance with MAGMA observations. We also thank the staff at the ATNF for observing support and Robert Gruendl for providing the stellar mass surface density image. We acknowledge extensive use of NASA’s Astrophysics Data System Bibliographic Services. TW is supported by NSF grant 08-07323 and the University of Illinois. JO is supported by the National Radio Astronomy Observatory (NRAO) which is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. JLP is supported by an appointment to the NASA Postdoctoral Program at the Jet Propulsion Laboratory, California Institute of Technology, administered by Oak Ridge Associated Universities through a contract with NASA. AH, J-PB and DP are grateful to the Australian Research Council for financial assistance during this project via the Linkage International scheme (Australia–France Co-operation Fund in Astronomy). SK is supported in part by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) 2009-0062866. AH thanks Erik Rosolowsky, Adam Leroy, Alberto Bolatto, Kaye Marion and Michael Murphy for helpful discussions. We thank the referee for constructive criticism that improved the analysis in this paper.
Funding AgencyGrant Number
NSFAST 08-07323
University of IllinoisUNSPECIFIED
National Radio Astronomy ObservatoryUNSPECIFIED
NASA Postdoctoral ProgramUNSPECIFIED
Australian Research CouncilUNSPECIFIED
National Research Foundation of KoreaUNSPECIFIED
Ministry of Education, Science and Technology (Korea)2009-0062866
Subject Keywords:ISM: clouds; ISM: molecules; galaxies: ISM; Magellanic Clouds
Issue or Number:3
Record Number:CaltechAUTHORS:20100903-105346164
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Official Citation:Hughes, A., Wong, T., Ott, J., Muller, E., Pineda, J. L., Mizuno, Y., Bernard, J.-P., Paradis, D., Maddison, S., Reach, W. T., Staveley-Smith, L., Kawamura, A., Meixner, M., Kim, S., Onishi, T., Mizuno, N. and Fukui, Y. (2010), Physical properties of giant molecular clouds in the Large Magellanic Cloud. Monthly Notices of the Royal Astronomical Society, 406: 2065–2086. doi: 10.1111/j.1365-2966.2010.16829.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19782
Deposited By: Jason Perez
Deposited On:08 Sep 2010 14:58
Last Modified:09 Mar 2020 13:19

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