The radiation field of very luminous stars can influence the hydrodynamics of the gas in close binary systems. So, several models, other than the classical Roche model, have been proposed so far to describe the structure of a close binary in this particular case. Therefore, it is very important to include radiation pressure in order to improve the classical model, especially for binaries that contain at least one hot and luminous (early-type) component, where the influence of radiation is strongest. The aim of this work is thus to present a new model for such binaries, supported by a computer program. We also explore the implications of this new perspective to the system: the infeasibility of common envelope formation in the usual way, along with the shift of Lagrange points, and the shrinkage of the equipotential surfaces. Special attention has been given to the computation of surface gravity as an observational probe to the new model's credibility. The gravity field on the surface of the components, as well as in the vicinity of the system, is strongly affected by radiation pressure and therefore, gas kinematics have to be reviewed under the new model.
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