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3.6 and 4.5 μm Spitzer Phase Curves of the Highly-Irradiated Hot Jupiters WASP-19b and HAT-P-7b

Wong, Ian and Knutson, Heather A. and Kataria, Tiffany and Lewis, Nikole K. and Burrows, Adam and Fortney, Jonathan J. and Schwartz, Joel and Shporer, Avi and Agol, Eric and Cowan, Nicolas B. and Deming, Drake and Désert, Jean-Michel and Fulton, Benjamin J. and Howard, Andrew W. and Langton, Jonathan and Laughlin, Gregory and Showman, Adam P. and Todorov, Kamen (2016) 3.6 and 4.5 μm Spitzer Phase Curves of the Highly-Irradiated Hot Jupiters WASP-19b and HAT-P-7b. Astrophysical Journal, 823 (2). Art. No. 122. ISSN 0004-637X.

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We analyze full-orbit phase curve observations of the transiting hot Jupiters WASP-19b and HAT-P-7b at 3.6 and 4.5 μm, obtained using the Spitzer Space Telescope. For WASP-19b, we measure secondary eclipse depths of 0.485% ± 0.024% and 0.584% ± 0.029% at 3.6 and 4.5 μm, which are consistent with a single blackbody with effective temperature 2372 ± 60 K. The measured 3.6 and 4.5 μm secondary eclipse depths for HAT-P-7b are 0.156% ± 0.009% and 0.190% ± 0.006%, which are well described by a single blackbody with effective temperature 2667 ± 57 K. Comparing the phase curves to the predictions of one-dimensional and three-dimensional atmospheric models, we find that WASP-19b's dayside emission is consistent with a model atmosphere with no dayside thermal inversion and moderately efficient day–night circulation. We also detect an eastward-shifted hotspot, which suggests the presence of a superrotating equatorial jet. In contrast, HAT-P-7b's dayside emission suggests a dayside thermal inversion and relatively inefficient day–night circulation; no hotspot shift is detected. For both planets, these same models do not agree with the measured nightside emission. The discrepancies in the model-data comparisons for WASP-19b might be explained by high-altitude silicate clouds on the nightside and/or high atmospheric metallicity, while the very low 3.6 μm nightside planetary brightness for HAT-P-7b may be indicative of an enhanced global C/O ratio. We compute Bond albedos of 0.38 ± 0.06 and 0 ( <0.08 at lσ) for WASP-19b and HAT-P-7b, respectively. In the context of other planets with thermal phase curve measurements, we show that WASP-19b and HAT-P-7b fit the general trend of decreasing day–night heat recirculation with increasing irradiation.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Wong, Ian0000-0001-9665-8429
Knutson, Heather A.0000-0002-0822-3095
Kataria, Tiffany0000-0003-3759-9080
Lewis, Nikole K.0000-0002-8507-1304
Burrows, Adam0000-0002-3099-5024
Fortney, Jonathan J.0000-0002-9843-4354
Shporer, Avi0000-0002-1836-3120
Agol, Eric0000-0002-0802-9145
Cowan, Nicolas B.0000-0001-6129-5699
Deming, Drake0000-0001-5727-4094
Désert, Jean-Michel0000-0002-0875-8401
Fulton, Benjamin J.0000-0003-3504-5316
Howard, Andrew W.0000-0001-8638-0320
Laughlin, Gregory0000-0002-3253-2621
Todorov, Kamen0000-0002-9276-8118
Additional Information:© 2016 The American Astronomical Society. Received 2015 December 30; accepted 2016 March 24; published 2016 May 27. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This work is also based in part on observations obtained at the W. M. Keck Observatory using time granted by the University of Hawaii, the University of California, and the California Institute of Technology. We thank the observers who contributed to the measurements reported here and acknowledge the efforts of the Keck Observatory staff. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. This work was performed in part under contract with the Jet Propulsion Laboratory (JPL) funded by NASA through the Sagan Fellowship Program executed by the NASA Exoplanet Science Institute.
Funding AgencyGrant Number
NASA Exoplanet Science Institute (NExScI)UNSPECIFIED
Subject Keywords:planetary systems; stars: individual (WASP-19 and HAT-P-7) ; techniques: photometric
Issue or Number:2
Record Number:CaltechAUTHORS:20160701-101446347
Persistent URL:
Official Citation:Ian Wong et al 2016 ApJ 823 122
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68806
Deposited By: Ruth Sustaita
Deposited On:01 Jul 2016 17:53
Last Modified:09 Mar 2020 13:18

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