Ultracompact H II Regions with Extended Emission: The Complete View
Abstract
In this paper we present the results of a morphological study performed on a sample of 28 ultracompact \hiirs~located near extended free-free emission, using radio continuum observations at 3.6~cm with the C and D VLA~configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA~configurations, we compiled a final catalogue of 21 ultracompact \hiirs ~directly connected with the surrounding extended emission. The observed morphology of most of the ultracompact \hiirs~in radio continuum emission is irregular (single or multi-peaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. Radio continuum images superimposed on colour composite \textit{Spitzer} images reinforce the assignations of direct connection by the spatial coincidence between the ultracompact components and regions of saturated 24~\micron~emission. We also find that the presence of extended emission may be crucial to understand the observed infrared-excess because an underestimation of ionizing Lyman photons was considered in previous works.
Keywords
Cite
@article{arxiv.1912.08958,
title = {Ultracompact H II Regions with Extended Emission: The Complete View},
author = {Eduardo de la Fuente and Alicia Porras and Miguel A. Trinidad and Stanley E. Kurtz and Simon N. Kemp and Daniel Tafoya and José Franco and Carlos Rodríguez-Rico},
journal= {arXiv preprint arXiv:1912.08958},
year = {2019}
}
Comments
21 pages, 4 figures, to be Published on Monthly Notices of the Royal Astronomical Society (Accepted: December, 18, 2019)