2018MNRAS.480.4693L

We present the absolute properties of the double-lined eclipsing binary KIC 6206751 exhibiting multiperiodic pulsations. The Kepler light curve of this system was simultaneously solved with the radial-velocity data given by Matson et al. (2017). The results indicate that the binary star is a short-period semidetached system with fundamental parameters of M1 = 1.66 ± 0.04 M☉, M2 = 0.215 ± 0.006 M☉, R1 = 1.53 ± 0.02 R☉, R2 = 1.33 ± 0.02 R☉, L1 = 5.0 ± 0.6 L☉, and L2 = 0.96 ± 0.09 L☉. We applied multiple frequency analyses to the eclipse-subtracted light residuals and detected the 42 frequencies below 2.5 d-1. Among these, three independent frequencies of f2, f3, and f4 can be identified as high-order (38 <=n <= 40) low-degree (l=2) gravity-mode oscillations, whereas the other frequencies may be orbital harmonics and combination terms. The ratios between the orbital frequency and the pulsation frequencies are forb:f2-4 ≃ 2:3, which implies that the γ Dor pulsations of the detached primary star may be excited by the tidal interaction of the secondary companion. The short orbital period, and the low-mass ratio and M2 demonstrate that KIC 6206751 is an R CMa-type star, which is most likely evolving into an EL CVn star. Of seven well-studied R CMa-type stars, our program target is the only eclipsing binary with a γ Dor pulsating component.