Formaldehyde Absorption toward W51

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We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be ... continued below

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Kogut, A.; Smoot, G.F.; Bennett, C.L. & Petuchowski, S.J. April 1, 1988.

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We have measured formaldehyde (H{sub 2}CO) absorption toward the HII region complex W51A (G49.5-0.4) in the 6 cm and 2 cm wavelength rotational transitions with angular resolution of approximately 4 inch. The continuum HII region shows a large, previously undetected shell structure 5.5 pc along the major axis. We observe no H{sub 2}CO emission in regions of low continuum intensity. The absorption, converted to optical depth, shows a higher degree of clumping than previous maps at lower resolution. The good S/N of the maps allows accurate estimation of the complicated line profiles, showing some of the absorbing clouds to be quite patchy. We list the properties of the opacity spectra for a number of positions both in the clumps and in the more diffuse regions of the absorbing clouds, and derive column densities for the 1{sub 11} and 2{sub 12} rotational levels of ortho-formaldehyde.

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  • Journal Name: Astrophysical Journal; Journal Volume: 346; Related Information: Journal Publication Date: 1989

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  • Report No.: LBL--25141
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 893189
  • Archival Resource Key: ark:/67531/metadc883178

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  • April 1, 1988

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  • Sept. 21, 2016, 2:29 a.m.

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  • Sept. 21, 2017, 3:51 p.m.

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Kogut, A.; Smoot, G.F.; Bennett, C.L. & Petuchowski, S.J. Formaldehyde Absorption toward W51, article, April 1, 1988; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc883178/: accessed December 14, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.