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Tidal heating and stellar irradiation of Hot Jupiters

Published version
Peer-reviewed

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Authors

Jermyn, AS 
Tout, CA 
Ogilvie, GI 

Abstract

We study the interaction between stellar irradiation and tidal heating in gaseous planets with short orbital periods. The intentionally simplified atmospheric model we employ makes the problem analytically tractable and permits the derivation of useful scaling relations. We show that many tidal models provide thermal feedback, producing interior radiative zones and leading to enhanced g-mode dissipation with a wide spectrum of resonances. These resonances are dynamically tuned by the thermal feedback, and so represent a novel form of thermomechanical feedback, coupling vibrational modes to the very slow thermal evolution of the planet. We then show that stellar irradiation allows the heat produced by these modes to be trapped at depth with high efficiency, leading to entropy increase in the central convective region, as well as expansion of the planet's radius sufficient to match observed swelling. We find that thermally driven winds play an essential role in this process by making the thermal structure of the atmosphere spherically symmetric within a few scale heights of the photosphere. We characterize the relationship between the swelling factor, the orbital period and the host star and determine the time-scale for swelling. We show that these g modes suffice to produce bloating on the order of the radius of the planet over Gyr time-scales when combined with significant insolation and we provide analytic relations for the relative magnitudes of tidal heating and insolation.

Description

Keywords

planets and satellites: interiors, planet–star interactions

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

469

Publisher

Oxford University Press
Sponsorship
ASJ acknowledges support from the Goldwater scholarship and the Marshall scholarship. CAT thanks Churchill College for his fellowship.