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

ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES(2020)

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摘要
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 deg(2) of the southern Galactic plane (332 degrees < l < 334 degrees and -2 degrees < b <+2 degrees, 344 degrees < l < 355 degrees and -2 degrees < b< +2 degrees, 358 degrees < l < 4 degrees and +2 degrees < b<+6 degrees, 5 degrees < l < 10 degrees and -2 degrees < b <+2 degrees). 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 deg(2)) 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.
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