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The Southern H Ⅱ Region Discovery Survey. I: the Bright Catalog
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Abstract
The census of Galactic H Ⅱ regions is vastly incomplete in the southern sky. We use the Australia Telescope Compact Array to observe 4-10 radio continuum and hydrogen radio recombination line (RRL) emission from candidate H Ⅱ regions in the Galactic zone 250° Ⅱ region candidates and observe 282 fields in the direction of at least one previously known or candidate H Ⅱ region. We detect radio continuum emission and RRL emission in 275 (97.5%) and 258 (91.5%) of these fields, respectively. We catalog the ∼7 GHz radio continuum peak flux densities and positions of 80 previously known and 298 candidate H Ⅱ regions. After averaging ∼18 RRL transitions, we detect 77 RRL velocity components toward 76 previously known H Ⅱ regions and 267 RRL velocity components toward 256 H Ⅱ region candidates. The discovery of RRL emission from these nebulae increases the number of known Galactic H Ⅱ regions in the surveyed zone by 82% to 568 nebulae. In the fourth quadrant, we discover 50 RRLs with positive velocities, placing those sources outside the solar circle. Including the pilot survey, the Southern H Ⅱ Region Discovery Survey has now discovered 295 Galactic H Ⅱ regions. In the next data release, we expect to add ∼200 fainter and more distant nebulae.
Item Type: | Article |
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Authors/Creators: | Wenger, TV and Dickey, JM and Jordan, CH and Balser, DS and Armentrout, WP and Anderson, LD and Bania, TM and Dawson, JR and McClure-Griffiths, NM and Shea, J |
Keywords: | galaxy: kinematics and dynamics - galaxy: structure - (ISM:) Hii regions - ISM: kinematics and dynamics - radio lines: ISM - surveys, radio astronomy |
Journal or Publication Title: | Astrophysical Journal, Supplement Series |
Publisher: | Univ Chicago Press |
ISSN: | 0067-0049 |
DOI / ID Number: | 10.3847/1538-4365/aaf8ba |
Copyright Information: | Copyright 2019 The American Astronomical Society |
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