Eclipsing Binary Systems XZ Per and BO Vul with Complex Variations in Orbital Periods

Abstract

The variations in the orbital periods of the eclipsing binary systems XZ Per and BO Vul have been studied. It has been shown that the variations in the orbital period of the eclipsing binary XZ Per are equally well represented as a superposition of the secular decrease and cyclic variations or as a sum of two cyclic variations. In the first case, the monotonic component can be a consequence of the loss of angular momentum by the system due to magnetic braking, while cyclic variations can be explained by the presence of a third body in the system or by the magnetic activity of the secondary component with a convective shell. In the second case, it is possible to assume the presence of two additional bodies in the system, or to attribute one of the period oscillations to the light-time effect, and the other to the magnetic activity of the secondary component. The variations in the orbital period of the eclipsing binary system BO Vul can be represented as a superposition of the secular decrease and cyclic variations. The observed cyclic variations in the period can occur due to the presence of a third body in the system or due to the magnetic activity of the secondary component with a convective shell.