Phase Curves of WASP-33b and HD 149026b and a New Correlation between Phase Curve Offset and Irradiation Temperature
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Final Published Version
Author
Zhang, Michael
Knutson, Heather A.
Kataria, T.

Schwartz, Joel C.

Cowan, Nicolas B.

Showman, Adam P.
Burrows, Adam

Fortney, Jonathan J.

Todorov, Kamen

Desert, Jean-Michel

Agol, Eric

Deming, Drake
Affiliation
Univ Arizona, Dept Planetary SciUniv Arizona, Lunar & Planetary Lab
Issue Date
2018-01-24Keywords
astrochemistrymagnetohydrodynamics (MHD)
methods: data analysis
planetary systems
planets and satellites: atmospheres
planets and satellites: individual (HD 149026b, WASP-33b)
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IOP PUBLISHING LTDCitation
Phase Curves of WASP-33b and HD 149026b and a New Correlation between Phase Curve Offset and Irradiation Temperature 2018, 155 (2):83 The Astronomical JournalJournal
The Astronomical JournalRights
© 2018. The American Astronomical Society. All rights reserved.Collection Information
This 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 repository@u.library.arizona.edu.Abstract
We present new 3.6 and 4.5 mu m Spitzer phase curves for the highly irradiated hot Jupiter WASP-33b and the unusually dense Saturn-mass planet HD 149026b. As part of this analysis, we develop a new variant of pixel-level decorrelation that is effective at removing intrapixel sensitivity variations for long observations (>10 hr) where the position of the star can vary by a significant fraction of a pixel. Using this algorithm, we measure eclipse depths, phase amplitudes, and phase offsets for both planets at 3.6 and 4.5 mu m. We use a simple toy model to show that WASP-33b's phase offset, albedo, and heat recirculation efficiency are largely similar to those of other hot Jupiters despite its very high irradiation. On the other hand, our fits for HD 149026b prefer a very high albedo. We also compare our results to predictions from general circulation models, and we find that while neither planet matches the models well, the discrepancies for HD 149026b are especially large. We speculate that this may be related to its high bulk metallicity, which could lead to enhanced atmospheric opacities and the formation of reflective cloud layers in localized regions of the atmosphere. We then place these two planets in a broader context by exploring relationships between the temperatures, albedos, heat transport efficiencies, and phase offsets of all planets with published thermal phase curves. We find a striking relationship between phase offset and irradiation temperature: the former drops with increasing temperature until around 3400 K and rises thereafter. Although some aspects of this trend are mirrored in the circulation models, there are notable differences that provide important clues for future modeling efforts.ISSN
1538-3881Version
Final published versionSponsors
NASA; Sloan FoundationAdditional Links
http://stacks.iop.org/1538-3881/155/i=2/a=83?key=crossref.dfd28c700cf003259f7f563ae7809983ae974a485f413a2113503eed53cd6c53
10.3847/1538-3881/aaa458