Depolarizing isotropic collisions of the CN solar molecule with electrons

Abstract

Existence of linear polarization, formed by anisotropic scattering in the photosphere, has been demonstrated observationally as well as theoretically and is called second solar spectrum (SSS). The SSS is distinguished by its structure, which is rich in terms of information. In order to analyze the SSS, it is necessary to evaluate the (de)polarizing effect of isotropic collisions between CN solar molecules and electrons or neutral hydrogen atoms. This work is dedicated to calculations of the polarization transfer rates associated with CN–electron isotropic collisions. We show that usual rates serve as a proxy for polarization transfer rates. Then, we take advantage of available usual excitation collisional rates obtained via sophisticated quantum methods in order to derive the polarization transfer rates for the X 2Σ+– B 2Σ+ (violet) and X 2Σ+–A 2Π (red) systems of CN. Our approach is based on the infinite order sudden (IOS) approximation and can be applied for other solar molecules. We discuss the effectiveness of collisions with electrons on the SSS of the CN lines. Our results contribute to reducing the degree of complication in modeling the formation of the SSS of CN.