An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b

Megan Mansfield, Jacob L. Bean, Michael Line, Vivien Parmentier, Laura Kreidberg, Jean Michel Désert, Jonathan J. Fortney, Kevin B. Stevenson, Jacob Arcangeli, Diana Dragomir

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Secondary eclipse observations of several of the hottest hot Jupiters show featureless, blackbody-like spectra or molecular emission features, which are consistent with thermal inversions being present in those atmospheres. Theory predicts a transition between warmer atmospheres with thermal inversions and cooler atmospheres without inversions, but the exact transition point is unknown. In order to further investigate this issue, we observed two secondary eclipses of the hot Jupiter HAT-P-7b with the Hubble Space Telescope (HST) WFC3 instrument and combined these data with previous Spitzer and Kepler secondary eclipse observations. The HST and Spitzer data can be well fit by a blackbody with T = 2692 ±14 K, and the Kepler data point constrains the geometric albedo to A g = 0.077 ±0.006. We modeled these data with a three-dimensional (3D) GCM and one-dimensional (1D) self-consistent forward models. The 1D models indicate that the atmosphere has a thermal inversion, weak heat redistribution, and water dissociation that limits the range of pressures probed. This result suggests that WFC3 observations of HAT-P-7b and possibly some other ultra-hot Jupiters appear blackbody-like because they probe a region near the tropopause where the atmospheric temperature changes slowly with pressure. Additionally, the 1D models constrain the atmospheric metallicity ([M/H]= -0.87+0.38 -0.34) and the carbon-to-oxygen ratio (C/O < 1 at 99% confidence). The solar composition 3D GCM matches the Spitzer data but generally underpredicts the flux in the WFC3 bandpass and cannot reproduce its featureless shape. This discrepancy could be explained by high atmospheric drag or nightside clouds and may be better understood through further observation with the James Webb Space Telescope.

Original languageEnglish (US)
Article number10
JournalAstronomical Journal
Volume156
Issue number1
DOIs
StatePublished - Jul 1 2018

Fingerprint

thermal emission
Jupiter (planet)
Hubble Space Telescope
Jupiter
emission spectra
eclipses
inversions
atmospheres
atmosphere
general circulation model
James Webb Space Telescope
tropopause
atmospheric temperature
transition points
albedo
coolers
drag
metallicity
confidence
dissociation

Keywords

  • planets and satellites: atmospheres
  • planets and satellites: gaseous planets
  • planets and satellites: individual (HAT-P-7b)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Mansfield, M., Bean, J. L., Line, M., Parmentier, V., Kreidberg, L., Désert, J. M., ... Dragomir, D. (2018). An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b. Astronomical Journal, 156(1), [10]. https://doi.org/10.3847/1538-3881/aac497

An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b. / Mansfield, Megan; Bean, Jacob L.; Line, Michael; Parmentier, Vivien; Kreidberg, Laura; Désert, Jean Michel; Fortney, Jonathan J.; Stevenson, Kevin B.; Arcangeli, Jacob; Dragomir, Diana.

In: Astronomical Journal, Vol. 156, No. 1, 10, 01.07.2018.

Research output: Contribution to journalArticle

Mansfield, M, Bean, JL, Line, M, Parmentier, V, Kreidberg, L, Désert, JM, Fortney, JJ, Stevenson, KB, Arcangeli, J & Dragomir, D 2018, 'An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b', Astronomical Journal, vol. 156, no. 1, 10. https://doi.org/10.3847/1538-3881/aac497
Mansfield M, Bean JL, Line M, Parmentier V, Kreidberg L, Désert JM et al. An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b. Astronomical Journal. 2018 Jul 1;156(1). 10. https://doi.org/10.3847/1538-3881/aac497
Mansfield, Megan ; Bean, Jacob L. ; Line, Michael ; Parmentier, Vivien ; Kreidberg, Laura ; Désert, Jean Michel ; Fortney, Jonathan J. ; Stevenson, Kevin B. ; Arcangeli, Jacob ; Dragomir, Diana. / An HST/WFC3 Thermal Emission Spectrum of the Hot Jupiter HAT-P-7b. In: Astronomical Journal. 2018 ; Vol. 156, No. 1.
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