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

N Amiri ; Wouter Vlemmings (Institutionen för rymd- och geovetenskap, Radioastronomi och astrofysik) ; A.J. Kemball ; H.J. van Langveide
Proceedings of the International Astronomical Union; Cosmic Masers - from OH to Ho (1743-9213). Vol. 8 (2012), S287, p. 54 - 58.
[Konferensbidrag, övrigt]

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.

Nyckelord: Stars; Magnetic Fields; Maser; Polarization


N. Amiri, W. H. T. Vlemmings, A. J. Kemball and H. J. van Langevelde (2012). VLBA SiO maser observations of the OH/IR star OH 44.8-2.3: magnetic field and morphology. Proceedings of the International Astronomical Union, 8, pp 54-58



Denna post skapades 2012-10-30. Senast ändrad 2015-02-16.
CPL Pubid: 165253