MULTI-PERIOD G-MODE PULSATIONS OF A PRE-HE-WD STAR IN THE ECLIPSING BINARY KIC 9164561

ABSTRACT We report the discovery of a new pulsating pre-He-WD in the EL CVn-type binary KIC 9164561. Light curve modeling and frequency analysis of the binary system were carried out based on short-cadence Kepler photometry. Combined with the radial-velocity solution, revised physical parameters of the binary system were determined. The component KIC 9164561B was confirmed to be a pre-He-WD star with M = 0.213 0.012 M , R = 0.283 0.006 R , and T eff = 10650 200 K. In addition to the light changes due to an eclipse, pulsational light variations of the pre-He-WD star were detected. The Fourier analysis reveals at least 52 frequencies, with the dominant one at 313.4 Hz. A brief mode identification indicates that the pre-He-WD star pulsates in g-modes with an average period spacing of Δ l = 1 = 80.87 s. Moreover, a number of multiplets due to rotational splitting were identified from the frequency spectra. The rotational period of the pulsating pre-He-WD star was found to equal to the orbital period, indicating that KIC 9164561B is in synchronous rotation.