Polarimetry of Symbiotic Stars

Abstract

Five symbiotic stars have been observed for linear polarization (UBVRI) in September 1981. Three systems, CH Cyg, CI Cyg and AG Peg show intrinsic polarization while in the case of Z And and AX Per the observed polarization seems to be mostly of interstellar origin. The position angle of polarization of CI Cyg and AG Peg rotates strongly vs. wavelength, as observed also for CH Cyg in 1977–80. The polarization of CH Cyg has decreased since May 1980, especially in the I, R and U bands, so that the maximum polarization is now in the blue (PB ∿ 0.3%). Probably we are monitoring the formation, growth and disappearance of dust particles in the atmosphere of this star. Two related systems, PU Vul (Nova Vul 1979) and R Aq1 (Mira) have polarization behaviour rather similar to that of symbiotic stars which suggests that the M type giant present in these systems is responsible for most of the intrinsic polarization.KeywordsDust ParticlePosition AngleWhite DwarfCrimean Astrophysical ObservatoryMaximum PolarizationThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.