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Astron. Astrophys. 364, 543-551 (2000)

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Long-term activity of the eclipsing binary AB Andromedae

G. Djuraevi 1, H. Rovithis-Livaniou 2 and P. Rovithis 3

1 Astronomical Observatory, Volgina 7, 11050 Belgrade, Yugoslavia (gdjurasevic@aob.bg.ac.yu)
2 Athens University, Department of Physics, Section of Astrophysics-Astronomy & Mechanics, Zografos, 157 84 Athens, Greece (elivan@atlas.uoa.gr)
3 Astron. Institute, National Observatory of Athens, P.O. Box 20048, 118 10 Athens, Greece

Received 5 February 1998 / Accepted 19 September 2000

Abstract

In the present study, the activity of the eclipsing binary AB And is examined by analysing the photometric data covering the period from 1968 till 1995.

The light curves corresponding to this period show significant differences and asymmetries, which are especially conspicuous in the height of the light-curve maxima and in the part following the secondary maximum as well as in the depth of the primary light-curve minimum. To explain the light asymmetries and variations, we used a model that involves spotted regions on the components. The analysis shows that AB And is in overcontact configuration ([FORMULA]). 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 during the examined period can be almost completely explained by the development and motion of the spotted areas on the components. According to the obtained results the spotted areas are probably formed at high latitudes and cover a significant part of the stellar surface; the change of their locations and sizes with time is examined.

Key words: stars: binaries: close – stars: binaries: eclipsing – stars: individual: AB And – stars: starspots

Send offprint requests to: G. Djuraevi

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001
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