Star Formation in W49A: Gravitational Collapse of the Molecular Cloud Core Toward a Ring of Massive Stars
Abstract
High-resolution molecular line and continuum radio images from the Hat Creek Radio Observatory and the Very Large Array suggest that the core of the W49A star-forming region is undergoing gravitational collapse. The radio continuum shows a 2-parsec ring of at least ten distinct ultracompact H-II regions, each associated with at least one O star. The ring is a region of large-scale, organized massive star formation. Recombination line velocities and HCO^+ excitation requirements indicate that the ring is rotating around 50,000 solar masses of material. Because the HCO+ (1-0) line shows red-shifted absorption but blue-shifted emission, the molecular cloud core is believed to be collapsing toward the center of the ring. The HCO^+ radial velocities, as well as H-I, H_2CO, and magnetic-field measurements, fit a simple model of inside-out gravitational collapse of a once magnetically supported cloud.
Additional Information
© 1987 American Association for the Advancement of Science. 27 May 1987; accepted 28 October 1987. This work was supported by NSF grant AST 84-16177.Additional details
- Eprint ID
- 54492
- Resolver ID
- CaltechAUTHORS:20150206-134353004
- AST 84-16177
- NSF
- Created
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2015-02-07Created from EPrint's datestamp field
- Updated
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2021-11-10Created from EPrint's last_modified field