Mass-loaded models can explain how a cometary morphology, ultracompact H II region can arise around a stationary star. The star is located in a density gradient in the mass-loading sources. Continuous mass-loss from the clumps embedded in the ionized gas allows the region to remain compact. The wind and radiation field from the central star set up a fully supersonic flow that is bounded by a recombination front. We develop the models further by calculating the velocity and density structure in detail for a variety of viewing angles, mass-loading laws and density scaleheights. The results are compared with observational work, and the agreements and differences are highlighted. We extend this model to show how a massive star located in a dense molecular ridge can give rise to a bipolar or ring morphology, depending on the viewing angle.
CITATION STYLE
Redman, M. P., Williams, R. J. R., & Dyson, J. E. (1998). Cometary and bipolar ultracompact HII regions. Monthly Notices of the Royal Astronomical Society, 298(1), 33–41. https://doi.org/10.1046/j.1365-8711.1998.01542.x
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