2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/9413We 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.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 figuresAstrophysicstext