Study of Brightness Variability of the Components of the Visual Binary System 61 Cyg Based on Observations at the Normal Astrograph of the Pulkovo Observatory

The variability of the components A and B of the visual binary system 61 Cyg is analyzed. The observations were made on the normal astrograph of the Pulkovo Observatory from 1956 through 1982 (a total of 296 brightness estimates). A search was undertaken for the periods of the variability of both components of the system with independent application of two periodogram analysis techniques: a sinusoidal approximation and the traditional Scargle method. As a comparison, the complete photometric series including all 296 values of the stellar magnitude and the yearly averages (27 values) were analyzed. This yielded a reliable value of about 15 years for the period of both components and a period of 8.5-9 years for the component 61 Cyg B that coincides with the 9.1-year period of the coronal and chromospheric activity discovered in 1978 by Wilson. 61 Cyg A was also found to have a less significant period of about 6 years, which coincides, to within the limits of accuracy, with a period of 7.5±1.7 years of the coronal and chromospheric activity previously noted by Hempelmann. Yet another less significant period of about 4 years of unknown origin was observed for 61 Cyg B. This may be the second harmonic of the fundamental period. We assume that the low accuracy of the estimated periods may be related to their instability owing to the complicated multicomponent character of the observed variability. A period of about 15 years detected for both components A and B may be related to astroclimatic or instrumental effects.