Orbital period modulation in hot Jupiter systems
Date Issued
2020
Author(s)
Abstract
We introduce a model for the orbital period modulation in systems with
close-by giant planets based on a spin-orbit coupling that transfers angular
momentum from the orbit to the rotation of the planet and viceversa. The
coupling is produced by a permanent non-axisymmetric gravitational quadrupole
moment assumed to be present in the solid core of the planet. We investigate
two regimes of internal planetary rotation, that is, when the planet rotates
rigidly and when the rotation of its deep interior is time dependent as a
consequence of a vacillating or intermittent convection in its outer shell. The
model is applied to a sample of very hot Jupiters predicting maximum
transit-time deviations from a constant-period ephemeris of approximately 50
seconds in the case of rigid rotation. The transit time variations of WASP-12,
currently the only system showing evidence of a non-constant period, cannot be
explained by assuming rigid rotation, but can be modelled in the time-dependent
internal rotation regime, thus providing an alternative to their interpretation
in terms of a tidal decay of the planet orbit.
Volume
497
Issue
3
Start page
3911
Issn Identifier
0035-8711
Ads BibCode
2020MNRAS.497.3911L
Rights
open.access
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