Bow shock models of ultracompact H II regions

Journal Article · Fri Mar 01 04:00:00 EST 1991 · Astrophysical Journal; (USA)

DOI:https://doi.org/10.1086/169769· OSTI ID:5867033

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

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1. NASA, Ames Research Center, Moffett Field, CA (USA) Joint Institute for Laboratory Astrophysics, Boulder, CO (USA) JPL, Pasadena, CA (USA) Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA) Washburn Observatory, Madison, WI (USA)

This paper presents models of ultracompact H II regions as the bow shocks formed by massive stars, with strong stellar winds, moving supersonically through molecular clouds. The morphologies, sizes and brightnesses of observed objects match the models well. Plausible models are provided for the ultracompact H II regions G12.21 - 0.1, G29.96 - 0.02, G34.26 + 0.15, and G43.89 - 0.78. To do this, the equilibrium shape of the wind-blown shell is calculated, assuming momentum conservation. Then the shell is illuminated with ionizing radiation from the central star, radiative transfer for free-free emission through the shell is performed, and the resulting object is visualized at various angles for comparison with radio continuum maps. The model unifies most of the observed morphologies of ultracompact H II regions, excluding only those objects with spherical shells. Ram pressure confinement greatly lengthens the life of ultracompact H II regions, explaining the large number that exist in the Galaxy despite their low apparent kinematic ages. 32 refs.

• OSTI ID: 5867033
• Journal Information: Astrophysical Journal; (USA), Journal Name: Astrophysical Journal; (USA) Vol. 369; 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
AGE ESTIMATION
BRIGHTNESS
COMPUTERIZED SIMULATION
COSMIC GASES
COSMIC RADIO SOURCES
FLUID FLOW
FLUIDS
GALAXIES
GASES
H2 REGIONS
INTERSTELLAR SPACE
MAPS
MATHEMATICAL MODELS
MILKY WAY
MOLECULES
MORPHOLOGY
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
RADIATION TRANSPORT
SATELLITES
SHOCK WAVES
SIMULATION
SIZE
SPACE
STELLAR ACTIVITY
STELLAR WINDS
SUPERSONIC FLOW
WAVE PROPAGATION