New analysis indicates no thermal inversion in the atmosphere of HD 209458b

Hannah Diamond-Lowe, Kevin B. Stevenson, Jacob L. Bean, Michael Line, Jonathan J. Fortney

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

An important focus of exoplanet research is the determination of the atmospheric temperature structure of strongly irradiated gas giant planets, or hot Jupiters. HD 209458b is the prototypical exoplanet for atmospheric thermal inversions, but this assertion does not take into account recently obtained data or newer data reduction techniques. We reexamine this claim by investigating all publicly available Spitzer Space Telescope secondary-eclipse photometric data of HD 209458b and performing a self-consistent analysis. We employ data reduction techniques that minimize stellar centroid variations, apply sophisticated models to known Spitzer systematics, and account for time-correlated noise in the data. We derive new secondary-eclipse depths of 0.119% ± 0.007%, 0.123% ± 0.006%, 0.134% ± 0.035%, and 0.215% ± 0.008% in the 3.6, 4.5, 5.8, and 8.0 μm bandpasses, respectively. We feed these results into a Bayesian atmospheric retrieval analysis and determine that it is unnecessary to invoke a thermal inversion to explain our secondary-eclipse depths. The data are well fitted by a temperature model that decreases monotonically between pressure levels of 1 and 0.01 bars. We conclude that there is no evidence for a thermal inversion in the atmosphere of HD 209458b.

Original languageEnglish (US)
Article number66
JournalAstrophysical Journal
Volume796
Issue number1
DOIs
StatePublished - Nov 20 2014
Externally publishedYes

Fingerprint

eclipses
data reduction
extrasolar planets
inversions
atmospheres
atmosphere
gas giant planets
atmospheric temperature
Space Infrared Telescope Facility
Jupiter (planet)
centroids
retrieval
Jupiter
analysis
inversion
planet
air temperature
temperature
gas

Keywords

  • planetary systems
  • stars: individual (HD 209458)
  • techniques: photometric

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

New analysis indicates no thermal inversion in the atmosphere of HD 209458b. / Diamond-Lowe, Hannah; Stevenson, Kevin B.; Bean, Jacob L.; Line, Michael; Fortney, Jonathan J.

In: Astrophysical Journal, Vol. 796, No. 1, 66, 20.11.2014.

Research output: Contribution to journalArticle

Diamond-Lowe, Hannah ; Stevenson, Kevin B. ; Bean, Jacob L. ; Line, Michael ; Fortney, Jonathan J. / New analysis indicates no thermal inversion in the atmosphere of HD 209458b. In: Astrophysical Journal. 2014 ; Vol. 796, No. 1.
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