Ultracompact H II regions with extended emission: the case of G43.89-0.78 and its molecular environment
Artikel i vetenskaplig tidskrift, 2020

The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory (OVRO), Atacama Large Millimetric Array (ALMA), and the infrared Spitzer observatories are powerful facilities to study massive star formation regions and related objects such as ultra-compact (UC) H II regions, molecular clumps, and cores. We used these telescopes to study the UC H II region G43.89-0.78. The morphological study at arcminute scales using NVSS and Spitzer data shows that this region is similar to those observed in the bubble-like structures revealed by Spitzer observations. With this result, and including a physical characterization based on 3.6 cm data, we suggest G43.89-0.78 be classified as an UC H II region with Extended Emission because it meets the operational definition given in this paper comparing radio continuum data at 3.6 and 20 cm. For the ultra-compact component, we use VLA data to obtain physical parameters at 3.6 cm confirming this region as an UC H II region. Using ALMA observations, we detect the presence of a dense (2.6 x 10(7) cm(-3)) and small (similar to 2.0 arcsec; 0.08 pc) molecular clump with a mass of 220 M-circle dot and average kinetic temperature of 21 K, located near to the UC H II region. In this clump, catalogued as G43.890-0.784, water masers also exist, possibly tracing a bipolar outflow. We discover in this vicinity two additional clumps which we label as G43.899-0.786 (T-d = 50 K; M = 11 M-circle dot) and G43.888-0.787 (T-d = 50 K; M = 15 M-circle dot).

H II regions

ISM: molecules

Stars: massive

Infrared: ISM

Radio lines: ISM


Eduardo de la Fuente

Universidad de Guadalajara

Daniel Tafoya

Chalmers, Rymd-, geo- och miljövetenskap, Onsala rymdobservatorium

Miguel A. Trinidad

Universidad de Guanajuato

Alicia Porras

Instituto Nacional de Astrofísica, Óptica y Electrońica

Alberto Nigoche-Netro

Universidad de Guadalajara

Simon N. Kemp

Universidad de Guadalajara

Stanley E. Kurtz

Universidad Nacional Autonoma de Mexico

Jose Franco

Universidad Nacional Autonoma de Mexico

Carlos A. Rodriguez-Rico

Universidad de Guanajuato

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 497 4 4436-4447


Astronomi, astrofysik och kosmologi


Fusion, plasma och rymdfysik



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