The planetary system Kepler-27 revisited

Transit timing variations of planets in Kepler-27 were already reported in some papers, but the entire characterisation of them is still an open subject. Our main motivation for this paper is to investigate the dynamical behaviour of all planets and candidates in the systems. By using a MultiNest Bayesian inference tool, coupled to an efficient symplectic N-body integrator, we analyse the available TTV data of the objects in the system. We ran different configurations of planetary systems to compare them. We corroborate that Kepler-27b and Kepler-27c have actually properties of super-puffs planets, i.e., extremely low density planets with masses <8 M_⊕ and radii akin to those of giant planets ( 4 M_⊕< R < 6 R_⊕ ). We provide a constraint to the mass of Kepler-27d of 4^+3_-2 M_⊕ , which results in a density of ≲ 2.7 g cm^-3 . For the candidate planet KOI-841.04, we find four solutions for its location and mass, inhibiting a proper characterisation. We also studied the dynamical behaviour of planets Kepler-27b and Kepler-27c for a range of masses and periods of KOI-841.04 and the results show that the two planets do not notice any perturbation in these configurations. This indicates that the recent classification of this object as a false positive it is in fact correct.