The evolution of the theoretical bolometric albedo in close binary systems

Until now the bolometric albedo in close binary systems was computed only for a few, and sometimes unrealistic cases. In this paper we present, for the first time, the evolution of the bolometric albedo as a function of the external flux, of the geometry and of the evolutionary status of an irradiated star. A new numerical method, based on the isoentropy at the bottom of the perturbed and the non-irradiated hemispheres, is introduced. A variant of this numerical method was already used by us to predict gravity darkening exponents and it is appropriate to radiative and convective envelopes. The procedure can also combine consistently the coupling interior-envelope-atmospheres models. The theoretical predictions are compared with the inferred values of the bolometric albedo available in the literature when possible. A theoretical transition zone is predicted for log T-eff approximate to 3.8 which coincides approximately with that for gravity darkening exponents. This value cannot be confirmed by the observations as a result of the high scattering of the empirical points. More extensive and careful analysis of light curves of eclipsing binaries is needed in order to clarify the scenario.