Secular period changes in ten eclipsing binaries

Abstract

The photoelectric times of minima, available for the eclipsing binaries KO Aql, V566 Oph, AH Vir, AG Vir, 44i Boo B, RT And , SV Cam, Tv Cas, AT Lac and U Peg have been analysed to study their orbital periods. KO Aqi, V566 Oph, AH Vir, AG Vir and 44i Boo B show increase in their periods while RT And, SV CAm, TV Cas, AR Lac and U Peg exhibit decrease of period. Quadratic ephemeris for the primary times of minima for all the systems have been derived. The cause for the apparent secular change is conjectured to be the light-time effect, as no other mechanism seems appropriate to interpret the observed variations without difficulty. The need for future photoelectric observations of the times of minima and astrometric work for these systems is emphasized.