Reanalysis of the orbital period variations of two DLMR overcontact binaries: FG Hya and GR Vir

Abstract

We investigate orbital period changes of two deep, low mass ratio (DLMR) overcontact W UMa-type binaries, FG Hya and GR Vir. It is found that the orbital period of FG Hya shows a cyclic change with a period of . The cyclic oscillation may be due to a third body in an eccentric orbit, while the orbital period of GR Vir shows a periodic variation with a period of and an amplitude of A = 0.0352 d. The periodic variation of GR Vir can be interpreted as a result of either the light-time effect of an unseen third body or the magnetic activity cycle.