Cep Ab is a typical S-type planet, which occupies a nearly
perpendicular planetary orbit relative to the binary. Here we use the Markov
Chain Monte Carlo (MCMC) sampler to conduct full N-body fitting and derive
self-consistent orbital solutions for this hierarchical system. Then we employ
the Eccentric Kozai-Lidov (EKL) mechanism to explain the extremely inclined
orbit of S-type planet Cep Ab. The EKL mechanism plays an essential
role in exploring significant oscillations of the mutual inclination
between the planet and the secondary star. We perform
qualitative analysis and extensive numerical integrations to investigate the
flip conditions and timescales of Cep Ab's orbit. When the planetary
mass is 15 , the planet can reach
113 with the critical initial conditions of and . The timescale for the first orbital flip decreases
with the increase of the perturbation Hamiltonian. Flipping orbits of
Cep Ab are confirmed to have a large possibility to retain stable based on
surfaces of section and the secular stability criterion. Furthermore, we extend
the application of EKL to general S-type planetary systems with
, where the most intense excitation of
occurs when and , and the variation of planetary
mass mainly affect the flip possibility where .