Discovery of shell structure in the ultracompact H II region W3(OH)

Journal Article · Fri May 01 04:00:00 EDT 1981 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/158861· OSTI ID:6338111

Dreher, J W; Welch, W J

Maps of the compact H II region W3(OH) made with the VLA at 2 cm and 1.3 cm with high angular resolution, roughly-equal0.''2, reveal a shell structure in the ionized gas. The inner and outer radii are 2.0 x 10/sup 16/ cm, respectively, for a distance of 3 kpc. The shell, which is clumpy, has an electron density which ranges from 1.6 x 10/sup 5/ cm/sup -3/ to 3.3 x 10/sup 5/ cm/sup -3/ and an electron temperature of about 9400 K. Accurate postitions are reported for the nearby water vapor masers, and continuum upper limits (3sigma) of 4.2 mJy and 10.5 mJy at 2 cm and 1.3 cm, respectively, were found for the positions of the masers. The far-infrared luminosity of the object and the ultraviolet flux, obtained from the optically thin radio emission and corrected for dust absorption, are consistent with a central O7 main-sequence star. A comparison of the available infrared spectral data of the object with model calculations of Rowan-Robinson suggests that the H II region is surrounded by an extensive cloud of radius 1.7 x 10/sup 18/ cm, a radial ultraviolet optical depth of 100, and a mass of about 100 M/sub sun/. The shell appears to be the ionized inner edge of a dust enriched cocoon which formed around the star in its protostellar stage. A rough upper limit for the age of the H II region is 270 years.

• Research Organization: National Radio Astronomy Observatory
• OSTI ID: 6338111
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 245:3; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AMPLIFIERS
ATMOSPHERES
COSMIC DUST
COSMIC RADIO SOURCES
DUSTS
ELECTRONIC EQUIPMENT
ENERGY SPECTRA
EQUIPMENT
H2 REGIONS
LUMINOSITY
MAIN SEQUENCE STARS
MAPS
MASERS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
NEBULAE
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SPECTRA
STARS
STELLAR ATMOSPHERES