The association of OH and methanol masers in W3(OH) |
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| Authors: | S Etoka R J Cohen M D Gray |
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| Institution: | The University of Manchester, Jodrell Bank Observatory, Macclesfield, Cheshire SK11 9DL;The University of Manchester, School of Physics and Astronomy, Sackville Street Building, PO Box 88, Manchester M60 1QD |
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| Abstract: | We present single-baseline Multi-Element Radio-Linked Interferometer Network (MERLIN) measurements of excited OH 6.0-GHz masers and methanol 6.7-GHz masers for the source W3(OH). These allow us to compare the positions of individual maser spots of these two species to ～15 mas accuracy for the first time, and to compare these with previously published positions of ground-state OH masers near 1.7 GHz and excited-state OH masers near 4.7 GHz. There is a strong association between OH 6035-MHz and 1665-MHz masers. OH and methanol have very similar distributions, but associations of individual masers are relatively rare: most methanol 6.7-GHz masers are within 100 mas of OH 6.0-GHz masers, but only four methanol masers are within 15 mas of an OH 6.0-GHz maser. There are no correspondences of either species with excited OH 4.7-GHz masers. Zeeman splitting of the 6.0-GHz OH lines indicates an ordered magnetic field ranging from 3.2 to 14.4 mG. The magnetic fields estimated from co-propagating masers such as 6035 and 1665 MHz are generally in good agreement with each other. |
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| Keywords: | magnetic fields masers polarization stars: formation ISM: individual: W3(OH) radio lines: ISM |
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