Evolution of close binary systems with initial components of 2 and 1.5 M sun.

The evolution of the originally more massive stars of three close binary systems has been computed through the phase of mass exchange between the components. The systems have M1 + M2 = 3.5 M0., initial mass ratio 0.75 and three different initial separations of 7 R0. 10 Re and 15 Re. Conservation of total mass and total orbital angular momentum is assumed. The beginning of mass transfer occurs after the exhaustion of central hydrogen in the primaries. At the end of mass loss, these stars result in white dwarfs of 0.280 Me, 0.296 Me and 0.317 Me. A comparison with observations is given. On a calcule' l' volution des composantes originairement les plus massives de trois systemes binaires . La masse totale est 3,5 M0, le rapport initial des masses 0,75 et les initiales 7 Re, 10 Re, 15 Re. Les toiles primaires atteignent leurs lobes de Roche l'e'puisement de l' au centre. Leur volution a e't6 suivie pendant la phase de transfert de aux composantes secondaires en assumant la conservation de la masse et du moment angulaire total. A la fin du transfert de , les ex-primaires voluent en toiles naines blanches respectivement de 0,280 Me, 0,296 Me et 0,317 Me. On doune `me comparaison avec les observations. Key words: binary stars - evolution - mass exchange