A MERLIN Study of 6 GHz Excited-state OH & 6.7 GHz Methanol Masers in ON1

Abstract

MERLIN observations of 6.668-GHz methanol and both 6.031- and 6.035-GHz hydroxyl (OH) emission from the massive star-formation region ON1 are presented. These are the first methanol observations made in full polarization using 5 antennas of MERLIN, giving high resolution and sensitivity to extended emission. Maser features are found to lie at the southern edge of the ultra-compact HII region, following the known distribution of ground-state OH masers. The masers cover a region ~1 arcsec in extent, lying perpendicular to the H13CO+ bipolar outflow. Excited-state OH emission demonstrates consistent polarization angles across the strongest linearly polarized features which are parallel to the overall distribution. The linear polarizations vary between 10.0 and 18.5 per cent, with an average polarization angle of -60 deg +/- 28 deg. The strongest 6.668-GHz methanol features provide an upper limit to linear polarization of ~1 per cent. Zeeman splitting of OH shows magnetic fields between -1.1 to -5.8 mG, and a tentative methanol magnetic field strength of -18 mG is measured.

arXiv comment10 Pages, 5 Figures

References in corpus (10)

• The Distance to the Perseus Spiral Arm in the Milky Way
• Models of class II methanol masers based on improved molecular data
• The Magnetic Field in the Star-forming Region Cepheus A from Water Maser Polarization Observations
• Probing the Magnetic Field at Sub-Parsec Radii in the Accretion Disk of NGC 4258
• High resolution observations of 6.7-GHz methanol masers with the LBA
• Methanol Maser Polarization in W3(OH)
• Methanol in W3(H2O) and Surrounding Regions
• The structure of Onsala 1 star forming region
• Enhanced density and magnetic fields in interstellar OH masers
• Intrinsic properties of the magnetically collimated water maser jet of W43A

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• First images of 6.7-GHz methanol masers in DR21(OH) and DR21(OH)N
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• EVN observations of 6.7 GHz methanol maser polarization in massive star-forming regions. V. Completion of the flux-limited sample
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• Physical conditions around high-mass young star-forming objects via simultaneous observations of excited OH and methanol masers