2022AJ....164..177H -
Astron. J., 164, 177 (2022/November-0)
Extremely Inclined Orbit of the S-type Planet γ Cep Ab Induced by the Eccentric Kozai-Lidov Mechanism.
HUANG X. and JI J.
Abstract (from CDS):
γ Cep Ab is a typical S-type planet, which occupies a nearly perpendicular planetary orbit relative to the binary. Here, we use a Markov Chain Monte Carlo sampler to conduct a full N-body fitting and derive self-consistent orbital solutions for this hierarchical system. We then employ the eccentric Kozai-Lidov (EKL) mechanism to explain the extremely inclined orbit of the S-type planet γ Cep Ab. The EKL mechanism plays an essential part in our exploration of the significant oscillations of the mutual inclination imut between the planet and the secondary star. We perform a qualitative analysis and use extensive numerical integrations to investigate the flip conditions and timescales of γ Cep Ab's orbit. When the planetary mass is 15 MJup, the planet can reach imut ∼ 113° given the critical initial conditions of imut < 60° and e1 < 0.7. The timescale for the first orbital flip decreases with the increase of the perturbation Hamiltonian. The flipping orbits of γ Cep Ab are confirmed to have a large possibility of remaining 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 a1/a2 ≤ 0.1, where the most intense excitation of imut occurs when a1/a2 = 0.1 and e2 ∼ 0.8, and the variation in planetary mass mainly affects the flip possibility where e1 ≤ 0.3.
Abstract Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Exoplanet dynamics
Simbad objects:
4
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