Abstract
We present deep Very Large Array H66α radio recombination line (RRL) observations of the two cometary H II regions in DR 21. With these sensitive data, we test the “hybrid” bow shock/champagne flow model previously proposed for the DR 21 H II regions. The ionized gas down the tail of the southern H II region is redshifted by up to ~30 km s-1 with respect to the ambient molecular gas, as expected in the hybrid scenario. The RRL velocity structure, however, reveals the presence of two velocity components in both the northern and southern H II regions. This suggests that the ionized gas is flowing along cone-like shells, swept-up by stellar winds. The observed velocity structure of the well-resolved southern H II region is most consistent with a picture that combines a stellar wind with stellar motion (as in bow shock models) along a density gradient (as in champagne flow models). The direction of the implied density gradient is consistent with that suggested by maps of dust continuum and molecular line emission in the DR 21 region.
Original language | English |
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Article number | A39 |
Number of pages | 22 |
Journal | Astronomy & Astrophysics |
Volume | 563 |
Early online date | 3 Mar 2014 |
DOIs | |
Publication status | Published - Mar 2014 |
Keywords
- astro-ph.GA
- HII regions
- Stars: formation
- ISM: Individual objects: DR21
- ISM: kinematics and dynamics
- Radio lines: ISM