Infrared and radio measurements of the density structure of compact H II regions

Journal Article · Fri Jun 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168860· OSTI ID:6933000

Megeath, S T; Herter, T; Gull, G E; Houck, J R ^[1]

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1. Cornell Univ., Ithaca, NY (USA)

The density structure of compact H II regions is studied by comparing the ratio of the S III forbidden 33.47-micron and 18.71-micron emission lines and 5-GHz continuum maps. Electron densities are computed for DR 22, G29.9 - 0.0, G75.84 + 0.4, M8, M42, S158, W3, and W33. For DR 22, M42, and W3, the electron densities determined from the IR data are consistent with those derived from radio observations. The densities for S158 and M8 are quite low, implying that the S III emission is dominated by the diffuse ionized gas observed in the radio continuum. For G29.9 - 0.0, G75.84 + 0.4, and W33, the S III data give higher densities than predicted from radio observations. This implies that either these nebulae are filled with dense clumps of ionized gas which are not resolved in the radio maps, or that the S III zone is confined to the small, dense cores found in the radio maps of all three nebulae. 41 refs.

• OSTI ID: 6933000
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 356; ISSN ASJOA; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
COSMIC RADIO SOURCES
DENSITY
ELECTROMAGNETIC RADIATION
ELECTRON DENSITY
ELEMENT ABUNDANCE
EMISSION SPECTRA
FLUIDS
GASES
H2 REGIONS
INFRARED SPECTRA
IONIZED GASES
MORPHOLOGY
PHYSICAL PROPERTIES
RADIATIONS
RADIOWAVE RADIATION
SPECTRA