Cometary compact H II regions are stellar-wind bow shocks

Journal Article · Sun Apr 01 04:00:00 EDT 1990 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/168645· OSTI ID:6769993

Van Buren, D; Mac Low, M; Wood, D O.S.; Churchwell, E ^[1]

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1. Johns Hopkins Univ., Baltimore, MD (USA) Canadian Institute for Theoretical Astrophysics, Toronto (Canada) NASA, Ames Research Center, Moffett Field, CA (USA) Joint Institute for Laboratory Astrophysics, Boulder, CO (USA) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA) Washburn Observatory, Madison, WI (USA)

Comet-shaped H II regions, like G34.3 + 0.2, are easily explained as bow shocks created by wind-blowing massive stars moving supersonically through molecular clouds. The required velocities of the stars through dense clumps are less than about 10 km/s, comparable to the velocity dispersion of stars in OB associations. An analytic model of bow shocks matches the gross characteristics seen in the radio continuum and the velocity structure inferred from hydrogen recombination and molecular line observations. The champagne flow model cannot account for these structures. VLBI observations of masers associated with the shells of cometary compact H II regions should reveal tailward proper motions predominantly parallel to the shell, rather than perpendicular. It is predicted that over a decade baseline, high signal-to-noise VLA observations of this class of objects will show headward pattern motion in the direction of the symmetry axis, but not expansion. Finally, shock-generated and coronal infrared lines are also predicted. 57 refs.

• OSTI ID: 6769993
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 353; 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
AMPLIFIERS
COMETS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUID FLOW
H2 REGIONS
INTERSTELLAR SPACE
MASERS
MATHEMATICAL MODELS
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
MOTION
NEBULAE
ORIGIN
PROPER MOTION
RADIATIONS
RADIOWAVE RADIATION
SHOCK WAVES
SPACE
STELLAR ACTIVITY
STELLAR WINDS
SUPERSONIC FLOW
WAVE PROPAGATION