Effect of Aligned and Non-Synchronous Rotation in the Equilibrium Structure of Binary Systems

Abstract

The problem to study the equilibrium structure of stars distorted by rotational and tidal effect has great importance in astrophysics. Such a problem will help better to understand inner structure of binary system. Therefore, there is need to study the equilibrium structure of gaseous sphere. Analytic study of determining the equilibrium structure of rotationally and tidally distorted stellar models is quite complex. Therefore, investigators attempted to solve such problems in some approximate way. In one such attempt Mohan, Saxena and Aggarwal used Kippenhahn and Thomas averaging technique together with the results of Kopal on Roche equipotential, to determine the effects of rotation and tidal distortion on the equilibrium structure of binary stars. However, the problems of determining the equilibrium structure of aligned and non synchronously rotating stars have not been satisfactory tackled so far. In the present thesis an attempt has been made to study the effect of aligned and non synchronous rotation on the equilibrium structure of rotation and tidal distortion on the binary system. The thesis consists of three chapters and chapter wise summary of the work is presented below. Chapter one is introductory in nature where we discussed the astrophysical significance of studying the equilibrium structure of rotationally and tidally distorted stellar models. Chapter two deals with the concept of modified Roche equipotential of distorted stars which accounts for the aligned, non synchronous rotation of the binary system. The explicit expression for distortional parameters , , , and P T u v w f f are obtained using Kippenhahn and Thomas averaging technique along with the results of Roche equipotential. In this chapter we have also discussed how to find the equilibrium structure of rotationally and tidally distorted stellar models in presence of aligned and non synchronous rotation. The methodology developed in Chapter-II is next used in chapter III to determine the equilibrium structure of non synchronous rotating and tidally distorted polytropic models of stars. Computation is carried out to determine the inner structure as well as various physical parameters of the rotationally and tidally distorted polytropic models with various values of degree of non synchronous parameter f. Conclusion based on the study has finally been discussed.