Formaldehyde absorption toward W51

Abstract

view Abstract Citations (8) References (14) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Formaldehyde Absorption toward W51 Kogut, A. ; Smoot, G. F. ; Bennett, C. L. ; Petuchowski, S. J. Abstract Formaldehyde (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. Publication: The Astrophysical Journal Pub Date: November 1989 DOI: 10.1086/168057 Bibcode: 1989ApJ...346..763K Keywords: Formaldehyde; H Ii Regions; Interstellar Matter; Radiation Absorption; Supernova Remnants; Absorption Spectra; Astronomical Maps; Data Reduction; Opacity; Radio Sources (Astronomy); Astrophysics; INTERSTELLAR: MOLECULES; NEBULAE: H II REGIONS; NEBULAE: INDIVIDUAL ALPHANUMERIC: W51 full text sources ADS | data products SIMBAD (4)