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Co-propagation of maser emission at 1720 and 4765 MHz |
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| Authors: | M D Gray R J Cohen A M S Richards J A Yates D Field |
| Institution: | Department of Physics, UMIST, PO Box 88, Manchester M60 1QD;NRAL, Jodrell Bank, Macclesfield SK11 9DL;Department of Physical Sciences, University of Hertfordshire, College Lane, Hatfield AL10 9AB;nstitute of Physics and Astronomy, University of Aarhus, DK-8000, Aarhus, Denmark |
| Abstract: | MERLIN observations are presented of OH 4765-MHz and OH 1720-MHz masers in the massive star-forming region W3(OH). Two of the three intense spots of maser emission at 4765 MHz are spatially coincident with two similar spots at 1720 MHz in both left-hand circular (LHC) and right-hand circular (RHC) polarizations, to an accuracy of 15 mas. The spots also overlap in velocity when allowance is made for Zeeman splitting of the 1720-MHz line. We conclude that we have found two examples of masers in different rotational levels of OH which are co-propagating through the same column of gas and experiencing competitive gain effects. The third 4765-MHz maser spot was found to have no overlapping counterpart amongst the 1720-MHz masers. |
| Keywords: | masers radiative transfer circumstellar matter ISM: individual: W3(OH) radio lines: stars |