Equilibrium sequences of irrotational binary polytropic stars : The case of double polytropic stars

Abstract

Solutions to equilibrium sequences of irrotational binary polytropic stars in Newtonian gravity are expanded in a power of $ε=a_0/R$, where R and $a_0$ are the orbital separation of the binary system and the radius of each star for $R=\infty$. For each order of $ε$, we should solve ordinary differential equations for arbitrary polytropic indices n. We show solutions for polytropic indices n= 0.5, 1, 1.5 and 2 up to $ε^6$ orders. Our semi-analytic solutions can be used to check the validity of numerical solutions.

59 pages including 15 tables and 13 figures, revtex, accepted to Phys. Rev. D