2003/09/05 by W. H. T. Vlemmings, Vlemmings, W. H. T., P. J. Diamond +4
Physics and Astronomy · #Astro and Planetary Science #Scientific Research and Discoveries #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0309185
5 pages, 2 figures; to appear in the PASP conference proceeding of the VLBA 10th Anniversary Meeting
arxiv created 2003/09/05 · arxiv updated 2009/12/01
We present circular polarization measurements of circumstellar water masers around 2 Mira variables and 4 supergaint stars. Both an LTE and non-LTE method are used to analyze the circular polarization and total intensity spectra and to obtain the magnetic field strength. The non-LTE method is found to be able to reproduce the observations best. Using this, we find fields from a few hundred milliGauss up to a few Gauss, indicating a solar-type r^(-2) dependence of the magnetic field on the distance, which leads to stellar surface magnetic fields of up to several hundred Gauss. No linear polarization is detected to less than 1.5%.