PERIOD CHANGES OF FOUR CEPHEID VARIABLES

Abstract

We have analysed the AAVSO (2023) photometric (UBVRI) observations of several dozens of Cepheids and W Vir variables. These observations allowed us to find the period changes of four Cepheid variables: ζ Gem, VX Cyg, V Lac, TT Aql. Mean phase light curves were obtained for 3-5 time intervals of observations using trigonometrical polynomial approximations of data in the V-band. VX Cyg shows the period decrease in 400 days interval that is also accompanied by the decrease of asymmetry. It was impossible to find regularities of period changes of other variables within error estimates due to the relatively small amount of observed cycles.