3.6 and 4.5 μm SPITZER PHASE CURVES of the HIGHLY IRRADIATED HOT JUPITERS WASP-19b and HAT-P-7b

Ian Wong, Heather A. Knutson, Tiffany Kataria, Nikole K. Lewis, Adam Burrows, Jonathan J. Fortney, Joel Schwartz, Avi Shporer, Eric Agol, Nicolas B. Cowan, Drake Deming, Jean Michel Désert, Benjamin J. Fulton, Andrew W. Howard, Jonathan Langton, Gregory Laughlin, Adam P. Showman, Kamen Todorov

Research output: Contribution to journalArticle

48 Scopus citations

Abstract

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 and 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 and , 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 ( at ) 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.

Original languageEnglish (US)
Article number122
JournalAstrophysical Journal
Volume823
Issue number2
DOIs
StatePublished - Jun 1 2016

Keywords

  • planetary systems
  • stars: individual (WASP-19 and HAT-P-7)
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Wong, I., Knutson, H. A., Kataria, T., Lewis, N. K., Burrows, A., Fortney, J. J., Schwartz, J., Shporer, A., Agol, E., Cowan, N. B., Deming, D., Désert, J. M., Fulton, B. J., Howard, A. W., Langton, J., Laughlin, G., Showman, A. P., & Todorov, K. (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), [122]. https://doi.org/10.3847/0004-637X/823/2/122