KIC 7914906: An eclipsing heartbeat star with tidally excited oscillations and gamma Doradus/delta Scuti hybrid pulsations

We present the eclipsing heartbeat star KIC 9704906 with tidally excited oscillations (TEOs) and gamma Doradus/delta Scuti hybrid pulsations. The derived parameters show that it has an orbital period of P=8.7529108(1) d, a high eccentricity of e=0.467(3), and a high inclination of i=78.degrees 81(6). The mass ratio q=0.981(5) and relative radii (radius divided by the semi major axis) r(1) = 0.0369(2) and r(2)=0.0715(4) indicate that the secondary component has a smaller mass and a larger radius, and may have evolved off the main sequence. The eight derived TEO candidates, n=3, 4, 5, 6, 7, 12, 40, and 44 harmonics, are consistent with or close to the dominant spherical harmonic harmonic l=2, m=0, or +/- 2, assuming that the spin and orbital axes are aligned, and the pulsations are adiabatic and standing waves. We also identify eight independent frequency candidates, but one of them, f(7), is more like a modulation of a quasi-periodic signal and the orbits. According to the g-mode frequencies, we find that the rotation period of one component is 11.52(29) d. Although the masses and radii cannot be further constrained due to the lack of sufficient high-precision spectra, fascinating phenomena in the Fourier spectra are evident and valuable in this system.