Illumination in binaries^*

¹ URA 1280 du CNRS, Observatoire de Strasbourg, 11 rue de l'Université, F-67000 Strasbourg, France
² Max-Plank-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85740 Garching, Germany

Send offprint request to: J.-M. Hameury

Received: 10 July 1996
Accepted: 17 September 1996

Abstract

We give a simple, but accurate method that can be used to account for illumination in compact binary systems which have a low-mass companion, even if spherically symmetric illumination of the secondary star (not necessarily on the main sequence) is not assumed. This is done by introducing a multiplicative factor Φ in the Stefan-Boltzmann surface boundary condition, which accounts for the blocking of the intrinsic secondary flux by X-ray heating of the photospheric layers. Numerical fits and tables for Φ are given for unperturbed effective temperatures in the range K and in the range .