Atmospheric Circulations of Hot Jupiters as Planetary Heat Engines
AffiliationUniv Arizona, Lunar & Planetary Lab
Univ Arizona, Dept Planetary Sci
planets and satellites: atmospheres
planets and satellites: individual (HD 189733b, HD 209458b)
MetadataShow full item record
PublisherIOP PUBLISHING LTD
CitationAtmospheric Circulations of Hot Jupiters as Planetary Heat Engines 2018, 853 (2):133 The Astrophysical Journal
JournalThe Astrophysical Journal
Rights© 2018. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractBecause of their intense incident stellar irradiation and likely tidally locked spin states, hot Jupiters are expected to have wind speeds that approach or exceed the speed of sound. In this work, we develop a theory to explain the magnitude of these winds. We model hot Jupiters as planetary heat engines and show that hot Jupiters are always less efficient than an ideal Carnot engine. Next, we demonstrate that our predicted wind speeds match those from three-dimensional numerical simulations over a broad range of parameters. Finally, we use our theory to evaluate how well different drag mechanisms can match the wind speeds observed with Doppler spectroscopy for HD 189733b and HD 209458b. We find that magnetic drag is potentially too weak to match the observations for HD 189733b, but is compatible with the observations for HD 209458b. In contrast, shear instabilities and/or shocks are compatible with both observations. Furthermore, the two mechanisms predict different wind speed trends for hotter and colder planets than currently observed. As a result, we propose that a wider range of Doppler observations could reveal multiple drag mechanisms at play across different hot Jupiters.
VersionFinal published version
SponsorsJames McDonnell Foundation postdoctoral fellowship; NASA Earth and Space Science fellowship; Heising-Simons Foundation