Analysis of a 30-year series of photoelectric observations of RY Tauri. I. Search for possible periodicities

Searches for periodic variations in the brightness of RY Tauri over various time intervals are conducted on the basis of photoelectric observations made by the author at the Crimean Station of the Shternberg State Astronomical Institute (GAISh) from 1965 through 2000 and of data published by others. The total duration of the series of observations is 12500 days. The existence of a long cycle lasting about 2000 days is confirmed. Short periods owing to rotational modulation of the brightness are not always present. During a time when the brightness of the star was increasing in 1966, a period of 7.5 days showed up. The detection of fluctuations which might be identified with rotational modulation evidently depends on the star’s level of brightness. In 1993 and 1996, respectively, periods of 20.0 and 29.4 days were discovered which are most likely caused by inhomogeneities in the circumstellar disk.