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The Southern H Ⅱ Region Discovery Survey. I: the Bright Catalog


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Wenger, TV, Dickey, JM ORCID: 0000-0002-6300-7459, Jordan, CH, Balser, DS, Armentrout, WP, Anderson, LD, Bania, TM, Dawson, JR, McClure-Griffiths, NM and Shea, J 2019 , 'The Southern H Ⅱ Region Discovery Survey. I: the Bright Catalog' , Astrophysical Journal, Supplement Series, vol. 240, no. 2 , pp. 1-19 , doi: 10.3847/1538-4365/aaf8ba.

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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
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
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Copyright 2019 The American Astronomical Society

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