Program: GN-2015B-Q-1

In the last years some close post-common-envelope eclipsing binaries have been found to show cyclic eclipse timing variations. This effect is usually interpreted either as the gravitational interaction among circumbinary planets and the host binary -- known as light-travel-time effect, or as the quadrupole-moment variations in one magnetic active component -- known as Applegate mechanism. In the first case, the planets must either survived the evolution of the host binary or they have been formed as a consequence of its evolution. In the second case, the orbital variation is the result of the coupling between the binary orbit and changes in the shape of a magnetically active component. Here, we propose, for the first time, to detect by radial velocity method the circumbinary planet candidates around the evolved binary KIC09472174 using GRACES/GEMINI and solve the light-travel-time effect versus Applegate mechanism puzzle.