Seismic Study of the γ Doradus-type Pulsations in the Eclipsing Binary KIC 10486425

We present a photometric and spectroscopic analysis of the eclipsing binary KIC 10486425. Synthesis of the light curve and radial velocity measurements indicates that this binary is a circular, synchronized, detached system. The masses and radii of the two components are determined as M-1 = 1.54 M-circle dot, M-2 = 1.11 M-circle dot, R-1 = 1.47 R-circle dot and R-2 = 1.60 R-circle dot, respectively. The cooler secondary star is more evolved, while the primary is still on the zero-age main sequence, suggesting that KIC 10486425 could be an Algol system. After removal of the binarity effects from the observed Kepler data, multiple frequency analysis is applied to the outside-eclipse light residuals, revealing that the primary component of KIC 10486425 is a gamma Dor type pulsating star with a dominant period of 0.758 days. A total of 160 pulsation frequencies with significant confidence are extracted in the g-mode region, from which a period-spacing pattern is identified which clearly shows a downward slope. Synthesis of the period-spacing pattern leads to a mode identification of (1 = 2, m = 2) for the pulsations with an asymptotic period spacing of Delta Pi(l) (= 2) - 1803.5 s. The near- core rotation rate is derived as f(rot) = 0.161 day(-1), about 15% slower than the orbital frequency of this synchronized binary, suggesting that the core and the envelope rotate differentially.