Studies of the evolutionary relationship between detached and contact binaries

We estimate the extent to which there is an evolutionary relationship betwe en detached main sequence binaries and similar to KW, KW, and KP contact bi naries in the first mass-exchange phase. The current and initial distributi ons of close binaries of these types are calculated per unit volume of spac e in the vicinity of the Sun and used to demonstrate evolutionary transitio ns from law-mass, short-period, detached systems to contact binaries. (C) 2 001 MAIK "Nauka/Interperiodica".