Gravity Waves on Hot Extrasolar Planets. I. Propagation and Interaction with the Background

We study the effects of gravity waves, or g-modes, on hot extrasolar planets. These planets are expected to possess stably stratified atmospheres, which support gravity waves. In this paper, we review the derivation of the equation that governs the linear dynamics of gravity waves and describe its a...

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Bibliographic Details
Published in:The Astrophysical journal 2010-05, Vol.714 (1), p.904-914
Main Authors: Watkins, Chris, Cho, J. Y-K
Format: Article
Language:English
Subjects:
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ATMOSPHERES
Earth, ocean, space
EQUATIONS
Exact sciences and technology
FLUID MECHANICS
GRAVITY WAVES
HYDRODYNAMICS
MECHANICS
MOTION
PLANETS
ROTATION
SATELLITES
TURBULENCE
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Summary:We study the effects of gravity waves, or g-modes, on hot extrasolar planets. These planets are expected to possess stably stratified atmospheres, which support gravity waves. In this paper, we review the derivation of the equation that governs the linear dynamics of gravity waves and describe its application to a hot extrasolar planet, using HD 209458 b as a generic example. We find that gravity waves can exhibit a wide range of behaviors, even for a single atmospheric profile. The waves can significantly accelerate or decelerate the background mean flow, depending on the difference between the wave phase and mean flow speeds. In addition, the waves can provide significant heating ({approx}10{sup 2} to {approx}10{sup 3} K per planetary rotation), especially to the region of the atmosphere above about 10 scale heights from the excitation region. Furthermore, by propagating horizontally, gravity waves provide a mechanism for transporting momentum and heat from the dayside of a tidally locked planet to its nightside. We discuss work that needs to be undertaken to incorporate these effects in current atmosphere models of extrasolar planets.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/714/1/904