Investigation of multiple period changes of some variable stars

ROTSE (Robotic Optical Transient Search Experiment) telescopes, which are designed to find the sources of gamma-ray bursts in the optical region, are robotic telescopes, two of which are located in the southern hemisphere (Australia and Namibia) and two in the northern hemisphere (America and Turkey). The main purpose of these telescopes is to work in concert with the Compton Gamma-ray telescope to detect the optical sources of gamma-ray bursts detected by the satellite. When there is no warning from the satellite, the telescope makes scanning observations without a filter. The data we will use in this thesis are some of the results of these survey observations. As a result of scanning observations, the light curves of thousands of stars that have not been studied before have been obtained. In our study, we tried to classify variable stars that are not yet fully classified with the help of period analysis using the light curves of some of these stars. Since the number of stars is very large, we have based our study on semi-regular variable stars with multiple change periods. Semi-regular stars are of the pulsating variable star type and are especially important for evolution because they are associated with mira-type variables. Sound waves, which occur as a result of physical events in the internal structure of the star, deform the star and cause a change in its light curve. Since this change is directly related to the internal structure of the star, they give information about the evolution of the star.