EQUILIBRIUM STRUCTURES OF DIFFERENTIALLY ROTATING PRIMARY COMPONENTS OF BINARY STARS

In this paper a method is proposed for computing the equilibrium struc tures and various other observable physical parameters of the primary components of stars in binary systems assuming that the primary is mor e massive than the secondary and is rotating differentially about its axis. Kippenhahn and Thomas averaging approach (1970) is used in a man ner earlier used by Mohan, Saxena and Agarwal (1990) to incorporate th e rotational and tidal effects in the equations of stellar structure. Explicit expressions for the distortional terms appearing in the stell ar structure equations have been obtained by assuming a general law of differential rotation of the type omega(2)=b(0)+b(1)s(2)+b(2)s(4), wh ere omega is the angular velocity of rotation of a fluid element in th e star at a distance a from the axis of rotation, and b(0), b(1), b(2) are suitably chosen numerical constants. The expressions incorporate the effects of differential rotation and tidal distortions upto second order terms. The use of the proposed method has been illustrated by a pplying it to obtain the structures and observable parameters of certa in differentially rotating primary components of the binary stars assu ming the primary components to have polytropic structures.