Changes in the orbital period of the near-contact binary BF Vir

The published moments of light minima of the near-contact binary BF Vir have been compiled and the changes of its orbital period have been analyzed. The results show that the orbital period of this star contains a periodic change of 30 years while it undergoes a secular decrease. A study of the various physical mechanisms of orbital period changes shows that the existence of a third body with mass 0.2811 M. and orbital radius 10.2 AU may be used to interpret the periodic component of the orbital period variations. If this component is caused by the magnetic activity cycle of the secondary component star, then the total luminosity of the binary system should exhibit a cyclic variation with an amplitude of 0.097 L. and the same period as that of the orbital period changes. The secular decrease of the period may be due to the mass and angular momentum losses of the system. BF Vir is a short-period and near-contact binary system. It may evolve into an A-subtype contact binary via secular mass and angular momentum losses.