Long-Term Observations of Active Binaries

Abstract

The photoelectric photometry of selected 14 chromospherically active binaries has been made between 1978 and 1989. SV Cam, UV Psc, V471 Tau and ER Vul are short, and RS CVn, RT CrB, WW Dra, Z Her, MM Her, RT Lac, AR Lac, II Peg, LX Per, and SZ Psc are long period RS CVn type binaries. To reveal the photometric peculiarities of RT Lac and V471 Tau, they have been observed extensively. Almost all of the systems (except RT CrB) showed wave-like distortion in their light curves. The light curve and orbital period variations are discussed. A period for the variations of the brightness at mid-primary of RT Lac was estimated to be six years. The mean total brightness of V471 Tau seems to be changed with a period of about 18 years and an amplitude of about 0m.15. The orbital periods tend to decrease continuously. The light variations at mid-eclipses with an amplitude of wave-like distortion occur in short time intervals and seem to be the common property of all RS CVn type binaries. Starspot hypothesis appears to be inadequate for explaining all the phenomena observed in chromospherically active close binaries.