KIC2696703, A Kepler Eclipsing binary system with Gamma Dor Pulsations
Aunia Samadi Ghadim (IVS KU Leuven), Andrew Tkachenko (Institute for Astronomy, KU Leuven), Timothy Van Reeth (Institute for Astronomy, KU Leuven)

Binary systems are the main source of precise fundamental properties of stars, such as their masses, radii, and to some extend chemical compositions. These stellar characteristics are the key ingredients in many applications in stellar astrophysics, in particular when it concerns internal structure and evolution of stars. The theories of stellar structure and evolution are best probed with asteroseismology, the study of oscillations of stars through interpretation of frequencies, amplitudes, and phases of their individual pulsation modes. It is thus natural to combine these two complementary fields, asteroseismology and binary stars, to test and improve the current theoretical models. We investigate a short-period (P ~ 6 d) eclipsing binary system consisting of two nearly twin F-type stars (m1/m2 ~ R1/R2 ~ 1) that are also found to exhibit intrinsic variability in terms of gamma Dor-type g-mode oscillations. The Kepler space-based photometric data are complemented with high-resolution ground-based spectroscopic observations to characterize the system as a whole as well as its individual stellar components. The two stars are found to rotate synchronously with the orbit of the binary system; the individual spectral line profiles experience strong variability near the periastron - the result which we interpret as an interaction between stellar pulsation and dynamical tide due to non-zero eccentricity of the system. Preliminary analysis of the pulsation signal encoded in the Kepler photometry reveals four series of pulsation periods. These may originate from the same star and can be identified as dipole, quadrupole and octopole modes, with two series belonging to the latter category.