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

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.

Vlemmings, Wouter,1974Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)wouterv (author)
Kemball, A.Joint Institute for VLBI in Europe (JIVE) (author)
van Langevelde, H. J.University of Illinois (author)
Universiteit Leiden (UL)Chalmers tekniska högskola (creator_code:org_t)

In:Proceedings of the International Astronomical Union8:5287, s. 54-581743-92131743-9221

By the author/editor: Amiri, N.; Vlemmings, Woute ...; Kemball, A.; van Langevelde, ...

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NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Astronomy Astrop ...

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