Variations in the Orbital Periods of Eclipsing Binaries δLib and SXLyn

Variations in the orbital period of eclipsing binaries delta Lib and SXLyn were analyzed. It was shown that these variations can be represented with equal accuracy in two ways: either in the form of a superposition of secular decrease and cyclic variations or only in the form of cyclic fluctuations. Cyclic variations in the period of delta Lib in both cases can be due to the presence of a third body in the system. In the case of a quadratic representation, they can be also a consequence of the magnetic activity of the secondary component. For SXLyn, a superposition of two cyclic variations is found for both linear and quadratic representation. The lower-period variations in both cases can be due to the presence of a third body in the system. The longer-period variation can be a consequence of the magnetic activity of the secondary component. The secular decrease in the periods of both systems could be due to a loss of angular momentum due to magnetic braking.