Abstract
We have made CO(J = 2-1) observations toward the H II region RCW 49 and its ionizing source, the rich stellar cluster Westerlund 2, with the NANTEN2 submillimeter telescope. These observations have revealed that two molecular clouds in velocity ranges of -11 to +9 km s-1 and 11 to 21 km s -1, respectively, show remarkably good spatial correlations with the Spitzer IRAC mid-infrared image of RCW 49, as well a velocity structures indicative of localized expansion around the bright central regions and stellar cluster. This strongly suggests that the two clouds are physically associated with RCW 49. We obtain a new kinematic distance estimate to RCW 49 and Wd2 of 5.4+1.1 -1.4 kpc, based on the mean velocity and velocity spread of the associated gas. We argue that the acceleration of the gas by stellar winds from Westerlund 2 is insufficient to explain the entire observed velocity dispersion of the molecular gas, and suggest a scenario in which a collision between the two clouds 4 Myr ago may have triggered the formation of the stellar cluster.
Original language | English |
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Pages (from-to) | L115-L119 |
Number of pages | 5 |
Journal | Astrophysical Journal |
Volume | 696 |
Issue number | 2 |
DOIs | |
Publication status | Published - 2009 |
Externally published | Yes |
Bibliographical note
Copyright 2009 The American Astronomical Society. First published in the Astrophysical journal letters, 696(2), L115, 2009, published by IOP Publishing. The original publication is available at http://doi.org/10.1088/0004-637X/696/2/L115. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.Keywords
- Hii regions
- ISM: clouds
- ISM: individual (RCW 49)
- Open clusters and associations: individual (Westerlund 2)