A Survey for Hydroxyl in the THOR Pilot Region around W43

Abstract

We report on observations of the hydroxyl radical (OH) within The H{\sc I}, OH Recombination line survey (THOR) pilot region. The region is bounded approximately between Galactic coordinates l=29.2 to 31.5${}^{\circ }$ and b=-1.0 to +1.0${}^{\circ }$ and includes the high-mass star forming region W43. We identify 103 maser sites, including 72 with 1612\,MHz masers, 42 showing masers in either of the main line transitions at 1665 and 1667\,MHz and four showing 1720\,MHz masers. Most maser sites with either main-line or 1720\,MHz emission are associated with star formation, whereas most of the 1612\,MHz masers are associated with evolved stars. We find that nearly all of the main-line maser sites are co-spatial with an infrared source, detected by GLIMPSE. We also find diffuse OH emission, as well as OH in absorption towards selected unresolved or partially resolved sites. Extended OH absorption is found towards the well known star forming complex W43 Main.

arXiv commentaccepted for publication in MNRAS

References in corpus (50)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• Theory of Star Formation
• The Milky Way in Molecular Clouds: A New Complete CO Survey
• Control of star formation by supersonic turbulence
• GLIMPSE: I. A SIRTF Legacy Project to Map the Inner Galaxy
• Toward Understanding Massive Star Formation
• The McGill Magnetar Catalog
• ATLASGAL - The APEX Telescope Large Area Survey of the Galaxy at 870 microns
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Hi-GAL: the Herschel infrared Galactic Plane Survey
• Infrared Dark Clouds: precursors to star clusters
• The VLA Galactic Plane Survey
• The SCUBA Legacy Catalogue: Continuum Objects Detected by SCUBA
• The Southern Galactic Plane Survey: HI Observations and Analysis
• The initial conditions of stellar protocluster formation. I. A catalogue of Spitzer dark clouds
• ATLASGAL - Compact source catalogue: 330 < l < 21 degrees
• The Bolocam Galactic Plane Survey -- II. Catalog of the Image Data
• A general catalogue of 6.7 GHz methanol masers. I: data
• From Massive Protostars to a Giant HII Region: Submillimeter Imaging of the Galactic Mini-starburst W43
• The Co-ordinated Radio and Infrared Survey for High-Mass Star Formation - II. Source Catalogue
• The 6-GHz Multibeam Maser Survey I. Techniques
• The RMS Survey: 6 cm continuum VLA observations towards candidate massive YSOs in the northern hemisphere
• 12.2-GHz methanol masers associated with 1.2-mm dust clumps: Quantifying high-mass star formation evolutionary schemes
• Millimetre continuum observations of southern massive star formation regions. I. SIMBA observations of cold cores
• The Bolocam Galactic Plane Survey IX: Data Release 2 and Outer Galaxy Extension
• W43: the closest molecular complex of the Galactic Bar?
• Bipolar outflows in OH/IR stars
• The Southern Galactic Plane Survey: Polarized Radio Continuum Observations and Analysis
• Duchamp: a 3D source finder for spectral-line data
• Low-velocity shocks traced by extended SiO emission along the W43 ridges: witnessing the formation of young massive clusters
• ATLASGAL --- Complete compact source catalogue: 280\degr\ $<\ell <$ 60\degr
• The Mopra Southern Galactic Plane CO Survey
• A SCUBA imaging survey of ultracompact HII regions: The environments of massive star formation
• The ATCA/VLA OH 1612 MHz survey. III. Northern Galactic Plane
• A supernova remnant coincident with the slow X-ray pulsar AX J1845-0258
• Accurate water maser positions from HOPS
• H2O Maser Observations of Candidate Post-AGB Stars and Discovery of Three High-velocity Water Sources
• THOR - The HI, OH, Recombination Line Survey of the Milky Way - The pilot study: HI observations of the giant molecular cloud W43
• SiO Maser Survey of IRAS Sources in the Inner Galactic Disk
• SPLASH: The Southern Parkes Large-Area Survey in Hydroxyl - First Science from the Pilot Region
• Young massive stars in the ISOGAL survey II. The catalogue of bright YSO candidates
• The onset of high-mass star formation in the direct vicinity of the galactic mini-starburst W43
• Parkes full polarization spectra of OH masers - I. Galactic longitudes 350 through the Galactic Centre to 41
• A Hi-GAL study of the high-mass star-forming region G29.96-0.02
• Discovery of Pulsed OH Maser Emission Stimulated by a Pulsar
• An updated catalog of OH-maser-emitting planetary nebulae
• Search for radiative pumping lines of OH masers: I. The 34.6um absorption line towards 1612 MHz OH maser sources
• The spatiokinematical structure of H_2O and OH masers in the "water fountain" source IRAS 18460-0151
• Maser Source Finding Methods in HOPS
• Pilot Observations for MALT-45: A Galactic Plane Survey at 7mm

Cited by in corpus (14)

• High-Mass Star and Massive Cluster Formation in the Milky Way
• The HI/OH/Recombination line survey of the inner Milky Way (THOR): data release 2 and HI overview
• Probing the "Sea" of Galactic Cosmic Rays with Fermi-LAT
• The HI/OH/Recombination line survey of the inner Milky Way (THOR)
• Continuum sources from the THOR survey between 1 and 2 GHz
• The scaling relations and star formation laws of ministarburst complexes
• OH maser emission in the THOR survey of the northern Milky Way
• Inferring the composition of super-Jupiter mass companions of pulsars with radio line spectroscopy
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45 m telescope (FUGIN). VI. Dense gas and mini-starbursts in the W43 giant molecular cloud complex
• OH absorption in the first quadrant of the Milky Way as seen by THOR
• Polarization properties of OH emission in planetary nebulae
• ATLASGAL -- Relationship between dense star forming clumps and interstellar masers
• The hydroxyl satellite-line `flip' as a tracer of expanding HII regions
• OH in the diffuse interstellar medium: physical modelling and prospects with upcoming SKA precursor/pathfinder surveys