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Comparative analysis of molecular clouds in M31, M33, and the Milky Way

Sheth, Kartik and Vogel, Stuart N. and Wilson, Christine D. and Dame, T. M. (2008) Comparative analysis of molecular clouds in M31, M33, and the Milky Way. Astrophysical Journal, 675 (1). pp. 330-339. ISSN 0004-637X. doi:10.1086/524647.

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We present BIMA observations of a 2' field in the northeastern spiral arm of M31. In this region we find six giant molecular clouds (GMCs) that have a mean diameter of 57 ± 13 pc, a mean velocity width of 6.5 ± 1.2 km s^(−1), and a mean molecular mass of (3.0 ± 1.6) × 10^5 M☉. The peak brightness temperature of these clouds ranges from 1.6 to 4.2 K. We compare these clouds to clouds in M33 observed by Wilson & Scoville using the OVRO millimeter array and some cloud complexes in the Milky Way observed by Dame and coworkers using the CfA 1.2 m telescope. In order to properly compare the single-dish data to the spatially filtered interferometric data, we project several well-known Milky Way complexes to the distance of Andromeda and simulate their observation with the BIMA interferometer. We compare the simulated Milky Way clouds with the M31 and M33 data using the same cloud identification and analysis technique and find no significant differences in the cloud properties in all three galaxies. Thus, we conclude that previous claims of differences in the molecular cloud properties between these galaxies may have been due to differences in the choice of cloud identification techniques. With the upcoming CARMA telescope, individual molecular clouds may be studied in a variety of nearby galaxies. With ALMA, comprehensive GMC studies will be feasible at least as far as the Virgo cluster. With these data, comparative studies of molecular clouds across galactic disks of all types and between different galaxy disks will be possible. Our results emphasize that interferometric observations combined with the use of a consistent cloud identification and analysis technique will be essential for such forthcoming studies that will compare GMCs in the Local Group galaxies to galaxies in the Virgo cluster.

Item Type:Article
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Sheth, Kartik0000-0002-5496-4118
Wilson, Christine D.0000-0001-5817-0991
Additional Information:© 2008 The American Astronomical Society. Received 2006 June 28, accepted for publication 2007 September 28. We thank Leo Blitz, Greg Engargiola, Tamara Helfer, Andrew Harris, Lee Mundy, Marc Pound, Erik Rosolowsky, Peter Teuben, Stephen White, and Friedrich Wyrowski for helpful discussions. We acknowledge the use of NASA’s SkyView facility (http://, located at NASA Goddard Space Flight Center. We also acknowledge support for the BIMA array from the National Science Foundation under grant AST 99-81289 to the University of Maryland. We are grateful for the insightful and helpful comments by the referee, Elly Berkhuijsen, which greatly improved the manuscript.
Funding AgencyGrant Number
NSFAST 99-81289
Subject Keywords:galaxies: individual: M31; galaxies: individual: M33; galaxies: individual: Milky Way; galaxies: ISM; Local Group; radio lines: ISM
Issue or Number:1
Record Number:CaltechAUTHORS:20090515-091806362
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Official Citation:Comparative Analysis of Molecular Clouds in M31, M33, and the Milky Way Kartik Sheth, Stuart N. Vogel, Christine D. Wilson, and T. M. Dame 2008 ApJ 675 330-339 doi: 10.1086/524647
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:14233
Deposited By: Joy Painter
Deposited On:26 Aug 2009 18:35
Last Modified:08 Nov 2021 22:44

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