HIDING PLANETS BEHIND A BIG FRIEND: MUTUAL INCLINATIONS OF MULTI-PLANET SYSTEMS WITH EXTERNAL COMPANIONS

ABSTRACT The Kepler mission has detected thousands of planetary systems with one to seven transiting planets packed within 0.7 au from their host stars. There is an apparent excess of single-transit planet systems that cannot be explained by transit geometries alone, when a single planetary mutual i...

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Bibliographic Details
Published in:The Astronomical journal 2017-01, Vol.153 (1), p.42-42
Main Authors: Lai, Dong, Pu, Bonan
Format: Article
Language:English
Subjects:
Dynamical systems
Exact solutions
Extrasolar planets
Inclination
Mathematical analysis
Planetary systems
Planets
planets and satellites: dynamical evolution and stability
planets and satellites: formation
planets and satellites: terrestrial planets
Transit
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Summary:ABSTRACT The Kepler mission has detected thousands of planetary systems with one to seven transiting planets packed within 0.7 au from their host stars. There is an apparent excess of single-transit planet systems that cannot be explained by transit geometries alone, when a single planetary mutual inclination dispersion is assumed. This suggests that the observed compact planetary systems have at least two different architectures. We present a scenario where the "Kepler dichotomy" may be explained by the action of an external giant planet or stellar companion misaligned with the inner multi-planet system. The external companion excites mutual inclinations of the inner planets, causing such systems to appear as "Kepler singles" in transit surveys. We derive approximate analytic expressions (in various limiting regimes), calibrated with numerical calculations, for the mutual inclination excitations for various planetary systems and perturber properties (mass mp, semimajor axis ap, and inclination ). In general, the excited mutual inclination increases with and , though secular resonances may lead to large mutual inclinations even for small . We discuss the implications of our results for understanding the dynamical history of transiting planet systems with known external perturbers.
ISSN:0004-6256
1538-3881
DOI:10.3847/1538-3881/153/1/42