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VLBA SiO maser observations of the OH/IR star OH 44.8-2.3: magnetic field and morphology

Published online by Cambridge University Press:  24 July 2012

N. Amiri ,
W. H. T. Vlemmings ,
A. J. Kemball  and
H. J. van Langevelde
N. Amiri
Affiliation:
Sterrewacht Leiden, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
W. H. T. Vlemmings
Affiliation:
Chalmers University of Technology, Onsala Space Observatory, SE-439 92, Onsala, Sweden
A. J. Kemball
Affiliation:
Joint Institute for VLBI in Europe (JIVE), Postbus 2, 7990 AA Dwingeloo, The Netherlands
H. J. van Langevelde
Affiliation:
Department of Astronomy and Institute for Advanced Computing Applications and Technologies/NCSA, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801, USA
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Abstract

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We report on Very Long Baseline Array SiO maser observations of the OH/IR star OH 44.8 - 2.3. The observations show that the maser features form a ring located at a distance of 5.4 AU around the central star. The masers show high fractional linear polarization up to 100%. The polarization vectors are consistent with a dipole field morphology. Additionally, we report a tentative detection of circular polarization of 7% for the brightest maser feature. This indicates a magnetic field of 1.5 ± 0.3 G. The SiO masers and the 1612 MHz OH masers suggest a mildly preferred outflow direction in the circumstellar environment of this star. The observed polarization is consistent with magnetic field structures along the preferred outflow direction. This could indicate the possible role of the magnetic fields in shaping the circumstellar environment of this object.

Keywords

StarsMagnetic FieldsMaserPolarization
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 8 , Symposium S287: Cosmic Masers - from OH to H0 , January 2012 , pp. 54 - 58
Copyright
Copyright © International Astronomical Union 2012

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