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Star Formation in W49A: Gravitational Collapse of the Molecular Cloud Core Toward a Ring of Massive Stars

Welch, William J. and Dreher, J. W. and Jackson, J. M. and Terebey, S. and Vogel, S. N. (1987) Star Formation in W49A: Gravitational Collapse of the Molecular Cloud Core Toward a Ring of Massive Stars. Science, 238 (4833). pp. 1550-1555. ISSN 0036-8075. https://resolver.caltech.edu/CaltechAUTHORS:20150206-134353004

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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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.238.4833.1550 DOIArticle
http://www.sciencemag.org/content/238/4833/1550PublisherArticle
http://www.jstor.org/stable/1700974JSTORArticle
ORCID:
AuthorORCID
Jackson, J. M.0000-0002-3466-6164
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.
Funders:
Funding AgencyGrant Number
NSFAST 84-16177
Issue or Number:4833
Record Number:CaltechAUTHORS:20150206-134353004
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150206-134353004
Official Citation:WELCH, W. J., DREHER, J. W., JACKSON, J. M., TEREBEY, S., & VOGEL, S. N. (1987). Star Formation in W49A: Gravitational Collapse of the Molecular Cloud Core Toward a Ring of Massive Stars. Science, 238(4833), 1550-1555. doi: 10.1126/science.238.4833.1550
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54492
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:07 Feb 2015 01:07
Last Modified:24 Jan 2020 18:49

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