Magnetic field structure in the outer OH maser envelope of VX Sagittarii
Toruń Centre for Astronomy, Nicolaus Copernicus University, ul. Gagarina 11, 87100 Toruń, Poland
2 Jodrell Bank Observatory, University of Manchester, Macclesfield, Cheshire, SK11 9DL, UK
Corresponding author: M. Szymczak, email@example.com
Accepted: 15 March 2001
The OH 1612 MHz maser transition from the supergiant star VX Sgr has been imaged in all Stokes parameters using MERLIN. Numerous elliptically polarised components are distributed in a roughly symmetric envelope of a size similar to that measured in total maser intensity. The polarisation vectors are generally tangential to the circumstellar envelope, indicating a globally ordered magnetic field at the distance of about 1400 au from the supergiant. It is suggested that a predominance of projected radial magnetic lines and a displacement between the red- and blue-shifted parts of the envelope can be explained with a dipole field tilted at 20-30° to the line of sight.
Key words: masers / polarisation / stars: magnetic fields / stars: circumstellar matter / stars: supergiants / stars: individual: VX Sgr
© ESO, 2001