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Temperatures of galactic molecular clouds showing CO self-absorption

Phillips, T. G. and Knapp, G. R. and Wannier, P. G. and Huggins, P. J. and Werner, M. W. and Neugebauer, G. and Ennis, D. (1981) Temperatures of galactic molecular clouds showing CO self-absorption. Astrophysical Journal, 245 . pp. 512-528. ISSN 1538-4357. doi:10.1086/158826.

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The CO J=2- l line has been observed and, in most cases, mapped in 10 star-forming molecular clouds (W3, NGC 1333, NGC 2071, Mon R2, CRL 961, p Oph, W49N, W51A, DR 21, and Cep A). The CO J = 3-2 line has been observed in W3 and DR 21. The CO lines from all of these sources are strongly self-absorbed. By comparing our results with published CO (1-0) line profiles, we find that large corrections to the temperatures of the cloud cores, as measured by the CO (1-0) lines, are required. The corrections for self-absorption bring the CO brightness temperatures into closer agreement with the grain temperatures inferred from far-infrared photometry. The absorbing gas appears to have a variety of geometrical relationships with the absorbed 'background' gas for this group of sources; in one or two cases there may be no physical connection between the absorbed and absorbing regions. For some CO sources, the combined CO data indicate the presence of velocity gradients; however, whether these are due to expansion or collapse cannot be decided on the basis of the presently available data.

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Knapp, G. R.0000-0002-9259-1164
Additional Information:© 1981 American Astronomical Society. Received 1980 August 20; accepted 1980 October 22. We thank the staff of the Owens Valley Radio Observatory and of the Palomar Observatory for their help in support of this work. Research in millimeter-wave astronomy at the California Institute of Technology is supported by the National Science Foundation via grant AST-79-16815. Part of this work was supported by NASA grant NGL 05-002-207.
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NASANGL 05-002-207
Subject Keywords:interstellar: molecules nebulae: general
Record Number:CaltechAUTHORS:20170308-113011537
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Official Citation:Temperatures of galactic molecular clouds showing CO self-absorption Phillips, T. G., Knapp, G. R., Wannier, P. G., Huggins, P. J., Werner, M. W., Neugebauer, G., , Astrophysical Journal, Part 1, vol. 245, Apr. 15, 1981, p. 512-528.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:74898
Deposited By: Ruth Sustaita
Deposited On:08 Mar 2017 20:46
Last Modified:15 Nov 2021 16:29

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