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Radio observations of ultracompact HII regions

Published online by Cambridge University Press:  08 November 2005

Luis F. Rodríguez
Affiliation:
Centro de Radioastronomía y Astrofísica, UNAM, Apdo. Postal 3-72, Morelia, Michoacán 58089 México email: l.rodriguez@astrosmo.unam.mx
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Abstract

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I review recent developments in the field of radio observations of ultracompact H II (UCHII) regions that have appeared in the literature since the last major review (Churchwell 2002). The morphology of UCHII regions continues to be a topic of research and recent studies of individual regions of star formation suggest modifications with respect to the results obtained from galactic plane surveys. I also briefly touch upon the question of the density structure of UCHII regions. Finally, I will also discuss the evidence of time variability in UCHII regions, and present examples of objects that are expanding, varying in flux density, or moving in the sky.