ON THE PROFILES AND THE POLARIZATION OF RAMAN-SCATTERED EMISSION-LINES IN SYMBIOTIC STARS - II - NUMERICAL SIMULATIONS

A Monte Carlo method is used to calculate the profiles and the polariz ation of the Raman-scattered O vr lines (lambda lambda 6827, 7088) in symbiotic stars, which are believed to consist of a binary system of a cool giant and a hot star with an emission nebula around it. A point- like isotropic UV radiation source is assumed, and a simple spherical wind model is adopted for the kinematics of the scattering material fr om the cool giant. We first investigate the case in which the incident line photons are described by a Gaussian profile having a width of 10 (4) K. We subsequently investigate the effects of the extended ionized region and non-spherical wind models, including a disc-type wind and a bipolar wind. The cases in which the emission source is described by non-Gaussian profiles are briefly studied. Finally, as an additional component for the kinematics of symbiotic stars, the orbital motion of the hot component around the cool giant is included and the effect on the spectropolarimetry is investigated. In this case the polarization direction changes around the red part of the Raman-scattered emission lines, when the observer's line of sight is perpendicular to the orbi tal plane; no such effect is seen when the line of sight lies in the o rbital plane. Furthermore, complex peak structures are seen in the deg ree of polarization and the polarized flux, which have often been obse rved in several symbiotic systems including RR Tel. Brief observationa l consequences and predictions are discussed in relation to the presen t and future spectropolarimetry of symbiotic stars. It is concluded th at spectropolarimetry may provide a powerful diagnostic for the physic al conditions of symbiotic stars.