A&A Supplement series, Vol. 123, June I 1997, 273-277
Received July 10; accepted September 17, 1996
J.-M. Hameury
and H. Ritter
Send offprint request: J.-M. Hameury
URA 1280 du CNRS, Observatoire de Strasbourg,
11 rue de l'Université, F-67000 Strasbourg, France
Max-Plank-Institut für Astrophysik,
Karl-Schwarzschild-Str. 1, 85740 Garching, Germany
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 
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 
are given for unperturbed effective temperatures in
the range 2500 - 5600 K and 
in the range 1.0 - 5.0.
keywords: accretion, accretion discs -- stars: binaries: close -- X-rays: stars -- methods: numerical