Equilibrium sequences of synchronized and irrotational binary systems composed of different mass stars in Newtonian gravity

Keisuke Taniguchi and Eric Gourgoulhon
Phys. Rev. D 65, 044027 – Published 28 January 2002
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Abstract

We study the equilibrium sequences of close binary systems in circular orbits and composed of different mass stars with a polytropic equation of state in Newtonian gravity. The solution is a multidomain spectral method which we have recently developed. The computations are performed for both cases of synchronized and irrotational binary systems with adiabatic indices γ=3, 2.5, 2.25, 2, and 1.8, and for three mass ratios: M1/M2=0.5, 0.2, and 0.1. It is found that the equilibrium sequences always terminate at a mass shedding limit (the appearance of a cusp on the surface of the less massive star). For synchronized binaries, this contrasts with the equal mass case, where the sequences terminate instead by a contact configuration. Regarding the turning point of the total angular momentum (or total energy) along a sequence, we find that it is difficult to get it for small mass ratios. Indeed, we do not find any turning points for M1/M2<~0.5 in the irrotational case. However, in the synchronized case, it becomes easier again to find one for mass ratios much smaller than M1/M20.2.

  • Received 6 August 2001

DOI:https://doi.org/10.1103/PhysRevD.65.044027

©2002 American Physical Society

Authors & Affiliations

Keisuke Taniguchi* and Eric Gourgoulhon

  • Département d’Astrophysique Relativiste et de Cosmologie, UMR 8629 du C.N.R.S., Observatoire de Paris, F-92195 Meudon Cedex, France

  • *Present address: Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Golm, Germany. Email address: keisuke@aei-potsdam.mpg.de
  • Email address: Eric.Gourgoulhon@obspm.fr

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Vol. 65, Iss. 4 — 15 February 2002

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