Stark, D. P. and Goss, W. M. and Churchwell, E. and Fish, V. L. and Hoffman, I. M. (2007) VLBA Observations of G5.89–0.39: OH Masers and Magnetic Field Structure. Astrophysical Journal, 656 (2). pp. 943-951. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100205-112353655
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We present VLBA observations of 1667 MHz OH maser emission from the massive star formation region G5.89-0.39. The observations were phase-referenced, allowing the absolute positions of the masers to be obtained. The 1667 MHz masers have radial velocities that span ~50 km s^(-1) but show little evidence of tracing the bipolar molecular outflow, as has been claimed in previous studies. We identify 23 Zeeman pairs through comparison of masers in left and right circular polarization. Magnetic field strengths range from -2 to +2 mG, and an ordered reversal in magnetic field direction is observed toward the southern region of the UC H II region. We suggest that the velocity and magnetic field structure of the 1667 MHz masers can be explained in the context of a model in which the masers arise in a neutral shell just outside a rapidly expanding ionized shell.
|Additional Information:||© 2007 American Astronomical Society. Print publication: Issue 2 (2007 February 20); received 2006 March 20; accepted for publication 2006 September 28. We thank the referee for helpful comments that improved the quality of the paper. D. P. S. thanks Debra Shepherd and Christer Watson for useful discussions. Facilities: VLBA.|
|Subject Keywords:||H II regions; ISM: individual (G5.89–0.39); ISM: magnetic fields; masers; stars: formation|
|Official Citation:||VLBA Observations of G5.89–0.39: OH Masers and Magnetic Field Structure D. P. Stark, W. M. Goss, E. Churchwell, V. L. Fish, and I. M. Hoffman 2007 ApJ 656 943-951 doi: 10.1086/509863|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||05 Feb 2010 23:49|
|Last Modified:||26 Dec 2012 11:45|
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