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Through a series of observations with the Australia Telescope Compact Array we have monitored the variability of ground-state hydroxyl maser emission from G12.889+0.489 in all four Stokes polarisation products. These observations were…

Astrophysics of Galaxies · Physics 2015-06-05 J. A. Green , J. L. Caswell , M. A. Voronkov , N. M. McClure-Griffiths

We report the first detection of circular polarization in 4.7 GHz excited OH masers in star-forming regions made using full Stokes measurements with the Green Bank 100m telescope. The Zeeman shift between the two circular components…

Astrophysics of Galaxies · Physics 2025-08-08 Derck P Smits , Paul Fallon

W75N is a star-forming region containing various ultracompact HII regions and OH, water, and methanol maser emission. Our VLBA map shows that the OH masers are located in a thin disk rotating around an O-star which is the exciting star of…

The active star-forming region W33B is a source of OH and H2O maser emission located in distinct zones around the central object. The aim was to obtain the complete Stokes pattern of polarised OH maser emission, to trace its variability and…

Astrophysics of Galaxies · Physics 2015-02-25 P. Colom , E. E. Lekht , M. I. Pashchenko , G. M. Rudnitskij

We have observed six high-mass star-forming regions in the 2 Pi 3/2, J = 7/2 lines of OH using the GBT in order to investigate whether the magnetic field, and hence the density, measured in absorption differs from that implied by maser…

Astrophysics · Physics 2009-11-10 Vincent L. Fish , Mark J. Reid , Karl M. Menten

The role of magnetic fields in the formation of high-mass stars is still under debate, and recent measurements of their orientation and strength by using polarized maser emissions are contributing new insights. Masers polarization, in…

Solar and Stellar Astrophysics · Physics 2015-06-04 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , B. Hutawarakorn Kramer

The Australia Telescope Compact Array (ATCA) has been used to make the first full polarization observations of 6.7 GHz methanol masers. Linear polarization was detected towards all four sources observed, at levels between a few and 10%,…

Astrophysics · Physics 2007-05-23 S. P. Ellingsen

Although the role of magnetic fields in launching molecular outflows in massive YSOs has been convincingly demonstrated by theoretical arguments, observationally, the alignment of the magnetic field lines with the molecular outflows is…

Astrophysics of Galaxies · Physics 2022-02-02 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , B. Hutawarakorn Kramer , A. Bartkiewicz

We present a survey of OH maser emission towards a sample of high mass protostellar objects made using the Nancay and GBT telescopes.OH maser emission was detected towards 63 objects with 36 new detections. There are 56 star-forming regions…

Astrophysics · Physics 2009-11-13 K. A. Edris , G. A. Fuller , R. J . Cohen

We present observations of massive star-forming regions selected from the IRAS Point Source Catalog. The observations were made with the Very Large Array and the Large Millimeter Telescope to search for Class I methanol masers. We made…

The polarized emission of astrophysical masers, especially OH and methanol lines, is an effective tool to study the magnetic field in high-mass star-forming regions. The magnetic field strength measurement via the Zeeman effect of OH maser…

Astrophysics of Galaxies · Physics 2025-08-21 A. Kobak , G. Surcis , A. Bartkiewicz , W. H. T. Vlemmings , M. Szymczak

We present MERLIN observations of OH, water and methanol masers towards the young high mass stellar object IRAS 20126+4104. Emission from the 1665-MHz OH, 22-GHz H_2O and 6.7-GHz CH_3OH masers is detected and all originates very close to…

Astrophysics of Galaxies · Physics 2011-07-05 K. A. Edris , G. A. Fuller , R. J. Cohen , S. Etoka

This study uses archival high frequency continuum data to expand the search for Hypercompact HII regions and determine the conditions at which they appear, as this stage high mass star formation is short-lived and rare. We use 23 GHz…

We present VLBA observations of the ground-state hydroxyl masers in W3(OH) at 0.02 km s-1 spectral resolution. Over 250 masers are detected, including 56 Zeeman pairs. Lineshapes are predominantly Gaussian or combinations of several…

Astrophysics · Physics 2008-11-26 Vincent L. Fish , Walter F. Brisken , Loránt O. Sjouwerman

We have carried out a series of observations of the 1665- and 1667-MHz transitions of the 2Pi_3/2, J=3/2 OH ground state towards six selected HII regions in the Large Magellanic Cloud (IRAS 05011-6815 and MRC 0510-689, 0513-694B, 0539-691,…

Astrophysics · Physics 2015-06-24 K. J. Brooks , J. B. Whiteoak

Full-polarization MERLIN and VLBA observations of the 1720 MHz maser emission from the OH molecule in the supernova remnant W28 are presented. Zeeman splitting (|B| \approx 0.75 mG) has been directly resolved between right- and…

Astrophysics · Physics 2009-11-10 Ian M. Hoffman , W. M. Goss , C. L. Brogan , M. J. Claussen

The Australia Telescope Compact Array (ATCA) has been used to determine positions for many southern methanol maser sites, with accuracy better than 1 arcsec. The results are presented here as a catalogue of more than 350 distinct sites,…

Astrophysics of Galaxies · Physics 2015-05-13 J. L. Caswell

Magnetic fields have only recently been included in theoretical simulations of high-mass star formation. The simulations show that magnetic fields play an important role in the formation and dynamics of molecular outflows. Masers, in…

Solar and Stellar Astrophysics · Physics 2015-06-16 G. Surcis , W. H. T. Vlemmings , H. J. van Langevelde , B. Hutawarakorn Kramer , L. H. Quiroga-Nunez

Four ground-state OH transitions were detected in emission, absorption and maser emission in the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). We re-observed these OH masers with the Australia Telescope Compact Array to obtain…

Astrophysics of Galaxies · Physics 2018-08-22 Hai-Hua Qiao , Andrew J. Walsh , Zhi-Qiang Shen

The 1612 and 1667 MHz OH maser lines have been measured in all four Stokes parameters in 47 proto-planetary nebula (PPN) candidates. Out of 42 objects detected, 40 and 34 are 1612 and 1667 MHz emitters, respectively. The spectral extent of…

Astrophysics · Physics 2009-11-10 M. Szymczak , E. Gerard