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arXiv · 1912.08958

Ultracompact H II Regions with Extended Emission: The Complete View

Eduardo de la Fuente·Alicia Porras·Miguel A. Trinidad·Stanley E. Kurtz·Simon N. Kemp·Daniel Tafoya·José Franco·Carlos Rodríguez-Rico
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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.

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Eduardo de la Fuente, Alicia Porras, Miguel A. Trinidad, Stanley E. Kurtz, Simon N. Kemp, Daniel Tafoya, José Franco, Carlos Rodríguez-Rico. 2019-12-19. Ultracompact H II Regions with Extended Emission: The Complete View. https://doi.org/10.1093/mnras%2Fstz3482

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