Long-term activity of the eclipsing binary AB Andromedae

Ln the present study, the activity of the eclipsing binary AB And is examin ed by analysing the photometric data covering the period from 1968 till 199 5. The light curves corresponding to this period show significant differences and asymmetries, which are especially conspicuous in the height of the ligh t-curve maxima and in the part following the secondary maximum as well as i n the depth of the primary light-curve minimum. To explain the light asymme tries and variations, we used a model that involves spotted regions on the components. The analysis shows that AB And is in overcontact configuration (f(over) similar to 15%). The Roche model with single spotted areas on both components yields a good fit of the observations for the whole set of the analysed light curves without any changes of the basic system's parameters. This indicates that the complex nature of the light-curve variations durin g the examined period can be almost completely explained by the development and motion of the spotted areas on the components. According to the obtain ed results the spotted areas are probably formed at high latitudes and cove r a significant part of the stellar surface; the change of their locations and sizes with time is examined.