Spectroscopic Diagnostics of Symbiotic Stars. II. Statistical Analyses of Highly Resolved Emission-Line Profiles

We obtained highly resolved spectroscopic data of 34 symbiotic stars at Hα, He II λ 4686, and [O III ] λ 5007. We analyzed the line profiles statistically to obtain clear common characteristics of the emission nebulae in symbiotic stars. We first carried out coarse analyses, which suggested differences in the line profiles between the quiescent and outburst phases. Second, we de-convolved the line profiles with multiple Gaussian components, and statistically dealt with each component in order to extract certain characteristics as a group. In the case of almost edge-on binary orbits, the relation between the characteristic velocities of the main, the broad wing, and the absorption components of Hα versus the orbital phase can be explained by the existence and interaction of stellar winds from cool and hot stars. The difference in the width of the main component of He II λ 4686 between the quiescent and the outburst phases and the changes in their radial velocities with the orbital phase support the idea that He⁺⁺ gas would distribute around a hot star. Double-peaked profiles of [O III ] λ 5007 lines and their relation to the orbital phase can be explained by bi-conical flows.