ORIGIN AND EVOLUTION OF SEMI-DETACHED BINARIES - BETA-LYRAE AND SV-CENTAURI

Based upon data published by Harmanec & Scholz (1993) and Hubeny and P lavec (1991), a possible set of initial mass values is determined for the semidetached binary system beta Lyrae. A conservative solution cor responds to a case AB of mass transfer and leads to several discrepanc ies with the observed characteristics. We find that beta Lyrae is appr oaching the end of the mass transfer, having evolved in a nonconservat ive way from an initial system of 9 M. + 7.65 M.. From these values th e evolution of both components is followed up to the present state and to the end of the mass transfer. This model is then used to discuss t he relationship between the pre-mass reversal system SV Centauri and b eta Lyrae.