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Formaldehyde absorption toward W51Formaldehyde (H2CO) absorption toward the H II region complex W51A (G49.5 - 0.4) in the 6 cm and 2 cm wavelength rotational transitions has been measured with angular resolution of about 0.15 pc. The continuum H II region shows a large, previously undetected shell structure 5.5 pc along the major axis. The absorption, converted to optical depth, shows a higher degree of clumping throughout the map than previous maps at lower resolution; in particular, two narrow regions of enhanced opacity are observed. The absorption in the velocity range 64-67 km/s LSR extends over most of the region, with an observed velocity gradient of 5.2 km/s pc. The opacity structure largely parallels the velocity structure, with a ridge of enhanced opacity to the north of the highest velocity feature. The S/N of the maps allows accurate modeling of the spectral profiles. Nine distinct clumps in the foreground clouds have been identified and parametrized, and column densities for the 1(11) and 2(12) rotational levels of orthoformaldehyde have been derived.
Document ID
19900029167
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kogut, A.
(California Univ. Berkeley, CA, United States)
Smoot, G. F.
(California, University Berkeley, United States)
Bennett, C. L.
(California Univ. Berkeley, CA, United States)
Petuchowski, S. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 14, 2013
Publication Date
November 15, 1989
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 346
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
90A16222
Funding Number(s)
CONTRACT_GRANT: DE-AC03-76SF-00098
CONTRACT_GRANT: NAS5-27592
Distribution Limits
Public
Copyright
Other

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