Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/66618

Title

The influence of far-ultraviolet radiation on the properties of molecular clouds in the 30 Dor region of the Large Magellanic Cloud

Author(s)

Pineda, Jorge L.;  Ott, Jurgen;  Klein, Ulrich;  Wong, Tony;  Muller, Erik;  Hughes, Annie

Abstract

We present a complete 12CO J = 1 → 0 map of the prominent molecular ridge in the Large Magellanic Cloud (LMC) obtained with the 22 m ATNF Mopra Telescope. The region stretches southward by ∼2◦ (or 1.7 kpc) from 30 Doradus, the most vigorous star-forming region in the Local Group. The location of this molecular ridge is unique insofar as it allows us to study the properties of molecular gas as a function of the ambient radiation field in a low-metallicity environment.We find that the physical properties of CO-emitting clumps within the molecular ridge do not vary with the strength of the far-ultraviolet radiation field. Since the peak CO brightness of the clumps shows no correlation with the radiation field strength, the observed constant value for CO-to-H2 conversion factor along the ridge seems to require an increase in the kinetic temperature of the molecular gas that is offset by a decrease in the angular filling factor of the CO emission. We find that the difference between the CO-to-H2 conversion factor in themolecular ridge and the outer MilkyWay is smaller than has been reported by previous studies of theCOemission: applying the same cloud identification and analysis methods to our CO observations of the LMC molecular ridge and CO data from the outer Galaxy survey by Dame et al., we find that the average CO-to-H2 conversion factor in the molecular ridge is XCO ≈ (3.9±2.5)×1020 cm−2 (K km s−1)−1, approximately twice the value that we determine for the outer Galaxy clouds. The mass spectrum and the scaling relations between the properties of the CO clumps in the molecular ridge are similar, but not identical, to those that have been established for Galactic molecular clouds.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Astrophysics and Supercomputing

Source

Astrophysical Journal, Vol. 703, no. 1 (Sep 2009), pp. 736-751

Publication year

2009

FOR Code(s)

0201 Astronomical and Space Sciences;  020110 Stellar Astronomy and Planetary Systems

Keyword(s)

ISM galaxies;  ISM molecules;  ISM structure;  Magellanic clouds;  Star formation

Publisher

Institute of Physics Publishing

ISSN

0004-637X

Publisher URL

http://dx.doi.org/10.1088/0004-637x/703/1/736

Copyright

Copyright © 2009. The American Astronomical Society. All rights reserved. The American Astronomical Society does not allow institutions to archive either the accepted manuscript or the published version of the article. However, you can find an earlier version of the full text here: http://arxiv.org/abs/0907.5186.

Peer reviewed