The Evolutionary Links of the Close Binaries

In this thesis,We have made a recapitulation about the studies in the history and the current state of the close binary evolution.The methods judging the evolutinary stage of the close binary are discussed from the observational and theoretical angles.Based on the observational data,the peoperties and the evolutionary stage of the different kinds of close binaries are obtained.And on the basis of the previous work,the difficulties in studying the evolutionary links are presented. photoelectric observations in B and V bands for short period eclipsing binary AP Aur are presented.The light-curve asymmetry with Max.Ⅱ brighter than Max.Ⅰ (called inverse O'Connell effect) is seen in both bands. The light curves have been analysed by using the 1992 version of Wilson-code,the orbital and physical parameters are obtained.The photometric solution indicates that AP Aur is a deep contact A-type W UMa binaries. According to the properties of the system AP Aur,the mechanisms causing the O'Connell effect are discussed. The analysis indicates that the asymmetry of the light curve of AP Aur can not be caused by the mass transfer. The mechanisms causing the O'Connell effect in this system may be the sun-like activities or circulation effect.Then the spotted parameters and the orbital parameters are obtained by using Wilson-code. Finally,the present evolutionary stage and the evolutionary trends in the future of this system are discussed.Conclutions are following: 1.AP Aur is an evolved binary with a secondary evolved away from the main sequence star. 2.AP Aur is a deep-contact binary with the extreme mass ratio,therefore it is instable.It probably coaleses to be a single star,or evolves into a cataclysmic variable by lossing the common envelope.