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The molecular cloud Sagittarius B2

Scoville, N. Z. and Solomon, P. M. and Penzias, A. A. (1975) The molecular cloud Sagittarius B2. Astrophysical Journal, 201 . pp. 352-365. ISSN 0004-637X.

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The structure of the Sgr B2 molecular cloud has been studied by detailed and extensive mappings of the CO, ^(13)CO, CS, and H_2CO (2-cm) transitions. The cloud consists of a dense core at the OH maser position plus a very large envelope 45 pc across. Sagittarius B2 is one of the most massive objects in the Galaxy, containing about 3 x 10^6 M_⊙ - an estimate arrived at independently from calculated ^(13)CO column densities, from application of the virial theorem, and from far-infrared measurements. The molecular gas has an average temperature T_k of ~ 20 K; that this is similar to the temperature of grains emitting far-infrared radiation is taken as evidence of near thermal equilibrium between dust grains and H_2. The dynamics of the gas in the cloud is found to be dominated by large-scale systematic motions with velocity not a monotonic function of radius.

Item Type:Article
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Scoville, N. Z.0000-0002-0438-3323
Additional Information:© 1975. The American Astronomical Society. Received 1975 February 19; revised 1975 April 17. We are grateful to Peter Wannier for his aid in obtaining some of the spectra used in Figure 2 and to John Kwan, Peter Goldreich, Mark Morris, and Dan Gezari for suggestions upon an earlier draft and to Claudine Gignoux for help in data reduction. This research is sponsored in part by a National Science Foundation grant GP-30400-X5 and by the Office of Naval Research under contract N0014-67-A-0094-0019 at the Owens Valley Radio Observatory.
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Office of Naval Research (ONR)N00014-67-A-0094-0019
Subject Keywords:molecules, interstellar — nebulae
Record Number:CaltechAUTHORS:20190403-153008190
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94427
Deposited By: George Porter
Deposited On:05 Apr 2019 22:04
Last Modified:03 Oct 2019 21:03

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