Accurate OH Maser Positions from the SPLASH Survey. III. The Final 96 deg2

Hai Hua Qiao, Shari L. Breen, José F. Gómez, J. R. Dawson, Andrew J. Walsh, James A. Green, Simon P. Ellingsen, Hiroshi Imai, Zhi-Qiang Shen

Research output: Contribution to journalArticle

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Abstract

We present high spatial resolution observations of ground-state OH masers achieved with the Australia Telescope Compact Array (ATCA). These observations targeted 253 pointing centers containing OH maser candidates at all four ground-state OH transitions identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) across 96 deg2 of the southern Galactic plane (332° < l < 334° and -2° < b < +2°, 344° < l < 355° and -2° < b < +2°, 358° < l < 4° and +2° < b < +6°, 5° < l < 10° and -2° < b < +2°). We detect maser emission toward 236 fields and suggest that 7 out of 17 nondetections are due to the slightly lower sensitivity of the ATCA observations, combined with some temporal variability. The superior resolution provided by the ATCA data has allowed us to identify 362 OH maser sites in the 236 target fields. Almost half (160 of 362) of these masers have been detected for the first time. Comparison between these 362 maser sites and information presented in the literature allowed us to categorize 238 sites as evolved star sites (66%), 63 as star formation (17%), 8 as supernova remnants, and 53 as unknown maser sites (15%). We present an analysis of the OH masers across the full SPLASH survey range (176 deg2) and find that the detection rate of 1.7 GHz radio continuum sources (18%) is lower than that previously found at 8.2 and 9.2 GHz (38%). We also find that the velocity separations of evolved star sites with symmetric 1612 MHz maser profiles are generally smaller than those with asymmetric profiles.

Original languageEnglish
Article number5
Pages (from-to)1-22
Number of pages22
JournalAstrophysical Journal, Supplement Series
Volume247
Issue number1
DOIs
Publication statusPublished - Mar 2020

Bibliographical note

Copyright 2020 The American Astronomical Society. First published in the Astrophysical Journal Supplement Series, 247(1), 5, 2020. The original publication is available at https://doi.org/10.3847/1538-4365/ab655d, published by IOP Publishing. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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