Secondary eclipse photometry of WASP-4b with warm spitzer

Ingrid M. Beerer, Heather A. Knutson, Adam Burrows, Jonathan J. Fortney, Eric Agol, David Charbonneau, Nicolas B. Cowan, Drake Deming, Jean Michel Desert, Jonathan Langton, Gregory Laughlin, Nikole K. Lewis, Adam Showman

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 μm taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission.We find secondary eclipse depths of 0.319% ± 0.031% and 0.343% ± 0.027% for the 3.6 and 4.5 μm bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2σ upper limit on |e cosω| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume727
Issue number1
DOIs
StatePublished - Jan 20 2011

Fingerprint

eclipses
photometry
planets
planet
planetary atmospheres
inversions
planetary atmosphere
absorbers
emission spectra
temperature inversions
Space Infrared Telescope Facility
upper atmosphere
extrasolar planets
temperature inversion
temperature profiles
temperature profile
cameras
time measurement
stars
heating

Keywords

  • Eclipses
  • Planetary systems
  • Stars: individual (WASP-4b)
  • Techniques: photometric

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Beerer, I. M., Knutson, H. A., Burrows, A., Fortney, J. J., Agol, E., Charbonneau, D., ... Showman, A. (2011). Secondary eclipse photometry of WASP-4b with warm spitzer. Astrophysical Journal, 727(1). https://doi.org/10.1088/0004-637X/727/1/23

Secondary eclipse photometry of WASP-4b with warm spitzer. / Beerer, Ingrid M.; Knutson, Heather A.; Burrows, Adam; Fortney, Jonathan J.; Agol, Eric; Charbonneau, David; Cowan, Nicolas B.; Deming, Drake; Desert, Jean Michel; Langton, Jonathan; Laughlin, Gregory; Lewis, Nikole K.; Showman, Adam.

In: Astrophysical Journal, Vol. 727, No. 1, 20.01.2011.

Research output: Contribution to journalArticle

Beerer, IM, Knutson, HA, Burrows, A, Fortney, JJ, Agol, E, Charbonneau, D, Cowan, NB, Deming, D, Desert, JM, Langton, J, Laughlin, G, Lewis, NK & Showman, A 2011, 'Secondary eclipse photometry of WASP-4b with warm spitzer', Astrophysical Journal, vol. 727, no. 1. https://doi.org/10.1088/0004-637X/727/1/23
Beerer IM, Knutson HA, Burrows A, Fortney JJ, Agol E, Charbonneau D et al. Secondary eclipse photometry of WASP-4b with warm spitzer. Astrophysical Journal. 2011 Jan 20;727(1). https://doi.org/10.1088/0004-637X/727/1/23
Beerer, Ingrid M. ; Knutson, Heather A. ; Burrows, Adam ; Fortney, Jonathan J. ; Agol, Eric ; Charbonneau, David ; Cowan, Nicolas B. ; Deming, Drake ; Desert, Jean Michel ; Langton, Jonathan ; Laughlin, Gregory ; Lewis, Nikole K. ; Showman, Adam. / Secondary eclipse photometry of WASP-4b with warm spitzer. In: Astrophysical Journal. 2011 ; Vol. 727, No. 1.
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abstract = "We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 μm taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission.We find secondary eclipse depths of 0.319{\%} ± 0.031{\%} and 0.343{\%} ± 0.027{\%} for the 3.6 and 4.5 μm bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2σ upper limit on |e cosω| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.",
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AB - We present photometry of the giant extrasolar planet WASP-4b at 3.6 and 4.5 μm taken with the Infrared Array Camera on board the Spitzer Space Telescope as part of Spitzer's extended warm mission.We find secondary eclipse depths of 0.319% ± 0.031% and 0.343% ± 0.027% for the 3.6 and 4.5 μm bands, respectively, and show model emission spectra and pressure-temperature profiles for the planetary atmosphere. These eclipse depths are well fit by model emission spectra with water and other molecules in absorption, similar to those used for TrES-3 and HD 189733b. Depending on our choice of model, these results indicate that this planet has either a weak dayside temperature inversion or no inversion at all. The absence of a strong thermal inversion on this highly irradiated planet is contrary to the idea that highly irradiated planets are expected to have inversions, perhaps due the presence of an unknown absorber in the upper atmosphere. This result might be explained by the modestly enhanced activity level of WASP-4b's G7V host star, which could increase the amount of UV flux received by the planet, therefore reducing the abundance of the unknown stratospheric absorber in the planetary atmosphere as suggested in Knutson et al. We also find no evidence for an offset in the timing of the secondary eclipse and place a 2σ upper limit on |e cosω| of 0.0024, which constrains the range of tidal heating models that could explain this planet's inflated radius.

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