SIMBAD references

A period study of an evolved Algol system XZ And has been attempted by using additional new data. The (O-C) diagram formed by the times of minimum light and thus orbital period of the system was found explainable in terms of the beat effect of two (or possibly three) cyclic variations differing in periods (P₁=137.5yr, P₂=36.8yr, and P₃=11.2yr) and amplitudes. We examined three possible explanatory mechanisms (apsidal motion of the slightly elliptical orbit, light time effect due to additional objects in the system, and the period modulation due to magnetic activity cycle of cool secondary component star). The observational evidences reject the possibility of apsidal motion effect on the period variation. One of the cyclic effects (probably with the shortest period P₃=11.2yr) may be related with the cyclic magnetic activity of the secondary component. The third body hypothesis requires one or two under-luminous stars (with total mass of about 3M_☉) around the system.