2017MNRAS.469.2907G

We present a new analysis of the transit timing variations displayed by the extrasolar planet Kepler-410Ab. We obtained and improved the orbital and physical parameters for the planet and analysed 70 transit times obtained by the Kepler satellite. In our analysis of the O-C diagram (observed minus calculated), we assumed that the observed changes in the transit times are probably caused by the gravitational influence of another body in the system. To determine the mass of the perturbing body, we considered the light-time effect and an analytical approximation of the perturbation model. The solutions resulting from both methods give comparable results, with an orbital period P₃ ∼ 970 d and a slightly eccentric orbit of the third body. We also showed that this orbit is nearly coplanar with the orbit of the Neptune-like planet Kepler-410Ab (orbital period 17.8 d). We propose two possible models for the perturbing body orbiting a common barycentre with Kepler-410A: (i) a single star with mass at least 0.906 M_☉, (ii) a binary star with the total mass of its components at least 2.15 M_☉. In both cases, the star Kepler-410B is on a long orbit (period more than 2200 yr). Small amplitude variations (∼5-8 min) detected in O-C residuals can be explained by the stellar activity of the host star (spots and pulsations), which affects the shape of the light curve during the transit. The presence of a single or binary companion of the mentioned masses heavily affects the total observed flux from the system. After removing the flux contamination from the Kepler-410A light curve, we found that the radius of the transiting planet Kepler-410Ab should be in the range from about 3.7 to 4.2 R_⊕.