High-resolution H I observations of H II regions. III - Photodissociation regions and the magnetic field near Orion B

Abstract

view Abstract Citations (17) References (85) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Resolution H i Observations of H II Regions. III. Photodissociation Regions and the Magnetic Field near Orion B van der Werf, Paul P. ; Goss, W. M. ; Heiles, Carl ; Crutcher, R. M. ; Troland, T. H. Abstract Results are presented of H I 1420 MHz observations of the H II region Orion B, carried out with the VLA of NRAO in the D-configuration. Three kinematically distinct H I layers are detected in absorption, and it is argued that one of these components originates in a photodissociation region (PDR) directly outside the ionization front in front of the H II region. In addition to the H I absorption, H I emission is detected, believed to originate in a PDR behind the H II region. The results are interpreted in terms of a clumby PDR model where the colder gas is located in dense clumps embedded in a warmer, low-density interclump medium. An analysis of the Zeeman effect indicated that the magnetic field strength and the total pressure in the dense PDR are higher than in the more tenuous cloud envelope. However, in the cloud envelope, the pressure is dominated by the magnetic field, while turbulent pressure dominates in the PDR. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172824 Bibcode: 1993ApJ...411..247V Keywords: H Ii Regions; Hydrogen; Interstellar Magnetic Fields; Interstellar Matter; Molecular Clouds; Orion Constellation; Photodissociation; Angular Resolution; Circular Polarization; High Resolution; Line Of Sight; Zeeman Effect; Astrophysics; ISM: H II REGIONS; ISM: INDIVIDUAL NAME: ORION B; ISM: MAGNETIC FIELDS; ISM: STRUCTURE; RADIO LINES: ISM full text sources ADS | data products SIMBAD (2)