2005/07/11 by W. H. T. Vlemmings, H. J. van Langevelde, Vlemmings, W. H. T. +3
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0507258
to appear in the porceedings of the "Stellar End Products" workshop, 13-15 April 2005, Granada, Spain (for publication in MmSAI vol.77). 5 pages, 3 figures
arxiv created 2005/07/11 · arxiv updated 2009/12/01
We present the analysis of the circular polarization, due to Zeeman splitting, of the water masers around a sample of late-type stars to determine the magnetic fields in their circumstellar envelopes. The magnetic field strengths in the water maser regions around the Mira variable stars U Ori and U Her are shown to be several Gauss while those of the supergiants S Per, NML Cyg and VY CMa are several hundred mG. We also show that large scale magnetic fields permeate the CSE of an evolved star; the polarization of the water masers around VX Sgr reveals a dipole field structure. We shortly discuss the coupling of the magnetic field with the stellar outflow, as such fields could possibly be the cause of distinctly aspherical mass-loss and the resulting aspherical planetary nebulae.