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The Molecular Ridge Close to 30 Doradus in the Large Magellanic Cloud

Published online by Cambridge University Press:  05 March 2013

Jürgen Ott*
Affiliation:
National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903, USA California Institute of Technology, 1200 E. California Blvd., Caltech Astronomy 104-25, Pasadena, CA 91125-2400, USA
Tony Wong
Affiliation:
Department of Astronomy, University of Illinois, 1002 W. Green St., Urbana, IL 61801, USA
Jorge L. Pineda
Affiliation:
Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
Annie Hughes
Affiliation:
Centre for Supercomputing and Astrophysics, Swinburne University of Technology, Hawthorn, VIC 3122, Australia CSIRO Australia Telescope National Facility, Cnr Vimiera & Pembroke Roads, Marsfield, NSW 2122, Australia
Erik Muller
Affiliation:
Centre for Supercomputing and Astrophysics, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
Zhi-Yun Li
Affiliation:
Department of Astronomy, University of Virginia, PO Box 400325, Charlottesville, VA 22903-4325, USA
Min Wang
Affiliation:
Purple Mountain Observatories, CAS, 2 West Beijing Road, Nanjing 210008, China
Lister Staveley-Smith
Affiliation:
School of Physics M013, University of Western Australia, Crawley, WA 6009, Australia
Yasuo Fukui
Affiliation:
Department of Astrophysics, Nagoya University, Furocho, Chikusaku, Nagoya 464-8602, Japan
Axel Weiß
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Christian Henkel
Affiliation:
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Ulrich Klein
Affiliation:
Argelander Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
*
LCorresponding author. Email: [email protected]
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Abstract

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With the ATNF Mopra telescope we are performing a survey in the 12CO(1–0) line to map the molecular gas in the Large Magellanic Cloud. For some regions we also obtained interferometric maps of the high density gas tracers HCO+ and HCN with the Australia Telescope Compact Array. Here we discuss the properties of the elongated molecular complex that stretches about 2 kpc southward from 30 Doradus. Our data suggest that the complex, which we refer to as the ‘molecular ridge’, is not a coherent feature but consists of many smaller clumps that share the same formation history. Likely triggers of molecular-cloud formation are shocks and shearing forces that are present in the surrounding south-eastern Hi overdensity region, a region influenced by strong ram pressure and tidal forces. The molecular ridge is at the western edge of the the overdensity region where a bifurcated velocity structure transitions into a single disk velocity component. We find that the 12CO(1–0) and Hi emission peaks in the molecular ridge are typically near each other but never coincide. A likely explanation is the conversion of warmer, low-opacity Hi to colder, high-opacity Hi from which H2 subsequently forms. On smaller scales we find that very dense molecular gas, as traced by interferometric HCO+ and HCN maps, is associated with star formation along shocked filaments and with rims of expanding shell-like structures, both created by feedback from massive stars.

Type
Research Article
Copyright
Copyright © Astronomical Society of Australia 2008

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