Accurate OH maser positions from the SPLASH pilot region

Abstract

We report on high spatial resolution observations, using the Australia Telescope Compact Array (ATCA), of ground-state OH masers. These observations were carried out toward 196 pointing centres previously identified in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH) pilot region, between Galactic longitudes of $334^{\circ }$ and $344^{\circ }$ and Galactic latitudes of $-2^{\circ }$ and $+2^{\circ }$. Supplementing our data with data from the MAGMO (Mapping the Galactic Magnetic field through OH masers) survey, we find maser emission towards 175 of the 196 target fields. We conclude that about half of the 21 non-detections were due to intrinsic variability. Due to the superior sensitivity of the follow-up ATCA observations, and the ability to resolve nearby sources into separate sites, we have identified 215 OH maser sites towards the 175 fields with detections. Among these 215 OH maser sites, 111 are new detections. After comparing the positions of these 215 maser sites to the literature, we identify 122 (57 per cent) sites associated with evolved stars (one of which is a planetary nebula), 64 (30 per cent) with star formation, two sites with supernova remnants and 27 (13 per cent) of unknown origin. The infrared colors of evolved star sites with symmetric maser profiles tend to be redder than those of evolved star sites with asymmetric maser profiles, which may indicate that symmetric sources are generally at an earlier evolutionary stage.

arXiv comment29 pages, 17 figures, accepted by ApJS, 162 on-line figures

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Cited by in corpus (11)

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• MALT-45: A 7mm survey of the southern Galaxy - II. ATCA follow-up observations of 44GHz class I methanol masers
• Accurate OH maser positions II. the Galactic Center region
• Accurate OH Maser Positions From The SPLASH Survey III: The Final 96 Square Degrees
• ATLASGAL -- Relationship between dense star forming clumps and interstellar masers
• The Evolutionary Status of Protostellar Clumps Hosting Class II Methanol Masers
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• Environmental conditions shaping star formation: The Carina Nebula
• Current stage of the ATCA follow-up for SPLASH
• Properties of Contracting Massive Protostellar Cores