Statistical analysis of the light curve of R Scuti

It is demonstrated that the light variations of the variable star R Scuti are a stationary stochastic process. Light oscillations with average durations of 71 and 143 days have been found; these oscillations are shown to be narrowband random noise, i.e., cycles. Peaks on the power spectrum corresponding to these cycles exceed the 99% confidence interval; these cycles are found to be independent. It is suggested that there is a cycle 348 days long in the light curve of R Scuti, and it is emphasized that the light-curve observations of stars must be performed simultaneously by means of correlations functions and the power spectrum. The description of the variability of RV Tauri type stars is also considered.