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Title: Searching for Compact Radio Sources Associated with UCH ii Regions

Abstract

Ultra-compact (UC)H ii regions represent a very early stage of massive star formation. The structure and evolution of these regions are not yet fully understood. Interferometric observations showed in recent years that compact sources of uncertain nature are associated with some UCH ii regions. To examine this, we carried out VLA 1.3 cm observations in the A configuration of selected UCH ii regions in order to report additional cases of compact sources embedded in UCH ii regions. With these observations, we find 13 compact sources that are associated with 9 UCH ii regions. Although we cannot establish an unambiguous nature for the newly detected sources, we assess some of their observational properties. According to the results, we can distinguish between two types of compact sources. One type corresponds to sources that are probably deeply embedded in the dense ionized gas of the UCH ii region. These sources are photoevaporated by the exciting star of the region and will last for 10{sup 4}–10{sup 5} years. They may play a crucial role in the evolution of the UCH ii region as the photoevaporated material could replenish the expanding plasma and might provide a solution to the so-called lifetime problem of these regions.more » The second type of compact sources is not associated with the densest ionized gas of the region. A few of these sources appear resolved and may be photoevaporating objects such as those of the first type, but with significantly lower mass depletion rates. The remaining sources of this second type appear unresolved, and their properties are varied. We speculate on the similarity between the sources of the second type and those of the Orion population of radio sources.« less

Authors:
; ;  [1]; ; ;  [2];  [3]
  1. Departamento de Astronomía, Universidad de Guanajuato, Apdo. Postal 144, 36000 Guanajuato, México (Mexico)
  2. Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Morelia 58089, México (Mexico)
  3. Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
Publication Date:
OSTI Identifier:
22663832
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 836; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPACTS; CONFIGURATION; COSMIC RADIO SOURCES; EVOLUTION; LIFETIME; MASS; PLASMA; STARS

Citation Formats

Masqué, Josep M., Trinidad, Miguel A., Rodríguez-Rico, Carlos A., Rodríguez, Luis F., Kurtz, Stan, Loinard, Laurent, and Dzib, Sergio A.. Searching for Compact Radio Sources Associated with UCH ii Regions. United States: N. p., 2017. Web. doi:10.3847/1538-4357/836/1/96.
Masqué, Josep M., Trinidad, Miguel A., Rodríguez-Rico, Carlos A., Rodríguez, Luis F., Kurtz, Stan, Loinard, Laurent, & Dzib, Sergio A.. Searching for Compact Radio Sources Associated with UCH ii Regions. United States. doi:10.3847/1538-4357/836/1/96.
Masqué, Josep M., Trinidad, Miguel A., Rodríguez-Rico, Carlos A., Rodríguez, Luis F., Kurtz, Stan, Loinard, Laurent, and Dzib, Sergio A.. Fri . "Searching for Compact Radio Sources Associated with UCH ii Regions". United States. doi:10.3847/1538-4357/836/1/96.
@article{osti_22663832,
title = {Searching for Compact Radio Sources Associated with UCH ii Regions},
author = {Masqué, Josep M. and Trinidad, Miguel A. and Rodríguez-Rico, Carlos A. and Rodríguez, Luis F. and Kurtz, Stan and Loinard, Laurent and Dzib, Sergio A.},
abstractNote = {Ultra-compact (UC)H ii regions represent a very early stage of massive star formation. The structure and evolution of these regions are not yet fully understood. Interferometric observations showed in recent years that compact sources of uncertain nature are associated with some UCH ii regions. To examine this, we carried out VLA 1.3 cm observations in the A configuration of selected UCH ii regions in order to report additional cases of compact sources embedded in UCH ii regions. With these observations, we find 13 compact sources that are associated with 9 UCH ii regions. Although we cannot establish an unambiguous nature for the newly detected sources, we assess some of their observational properties. According to the results, we can distinguish between two types of compact sources. One type corresponds to sources that are probably deeply embedded in the dense ionized gas of the UCH ii region. These sources are photoevaporated by the exciting star of the region and will last for 10{sup 4}–10{sup 5} years. They may play a crucial role in the evolution of the UCH ii region as the photoevaporated material could replenish the expanding plasma and might provide a solution to the so-called lifetime problem of these regions. The second type of compact sources is not associated with the densest ionized gas of the region. A few of these sources appear resolved and may be photoevaporating objects such as those of the first type, but with significantly lower mass depletion rates. The remaining sources of this second type appear unresolved, and their properties are varied. We speculate on the similarity between the sources of the second type and those of the Orion population of radio sources.},
doi = {10.3847/1538-4357/836/1/96},
journal = {Astrophysical Journal},
number = 1,
volume = 836,
place = {United States},
year = {Fri Feb 10 00:00:00 EST 2017},
month = {Fri Feb 10 00:00:00 EST 2017}
}