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Circular Polarization of Circumstellar Water Masers: Magnetic Fields of AGB stars

W. H. T. Vlemmings·P. J. Diamond·H. J. van Langevelde
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Abstract

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%.

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W. H. T. Vlemmings, P. J. Diamond, H. J. van Langevelde. 2003-09-05. Circular Polarization of Circumstellar Water Masers: Magnetic Fields of AGB stars. https://arxiv.org/abs/astro-ph/0309185

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