Theoretical Spectral Models of the Planet HD 209458b with a Thermal Inversion and Water Emission Bands

By Adam Burrows, I. Hubeny, J. Budaj, H. Knutson, D. Charbonneau. 2007

208 citations recorded by the source corpus.

We find that a theoretical fit to all the HD 209458b data at secondary eclipse requires that the day-side atmosphere of HD 209458b have a thermal inversion and a stratosphere. This inversion is caused by the capture of optical stellar flux by an absorber of uncertain origin that resides at altitude. One consequence of stratospheric heating and temperature inversion is the flipping of water absorption features into emission features from the near- to the mid-infrared, and we see evidence of such a water emission feature in the recent HD 209458b IRAC data of Knutson et al. In addition, an upper-atmosphere optical absorber may help explain both the weaker-than-expected Na D feature seen in transit and the fact that the transit radius at 24 μm is smaller than the corresponding radius in the optical. Moreover, it may be a factor in why HD 209458b's optical transit radius is as large as it is. We speculate on the nature of this absorber and the planets whose atmospheres may, or may not, be affected by its presence.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/50b6646d46d97dd2a184b27d20a5e124e744b5b1

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. D. Deming
5. D. Sing
6. Sara Seager
7. M. Line
8. M. Marley

Citations in the corpus

• Detection of atmospheric haze on an extrasolar planet: the 0.55–1.05 μm transmission spectrum of HD 189733b with the Hubble Space Telescope (2007, background): “In a similar context, a temperature inversion has recently been postulated in the atmosphere of the transiting planet HD 209458b by Burrows et al. (2007) to explain the emission spectrum recently observed by Knutson et al. (2007) during the secondary eclipse.”
• HST hot-Jupiter transmission spectral survey: evidence for aerosols and lack of TiO in the atmosphere of WASP-12b (2013, methodology): “Models were also computed with a variety of different metalicities, C/O ratios, and heat redistribution efficiency parameters as well as extra optical absorbers used by Burrows et al. (2007) to produce stratospheres and interpret Spitzer secondary eclipse data.”
• A NEW APPROACH TO ANALYZING HST SPATIAL SCANS: THE TRANSMISSION SPECTRUM OF HD 209458 b (2015, background): “In addition, the thermal properties of the planet have been investigated by a number of teams (e.g. Burrows et al. 2007; Knutson et al. 2008; Griffith 2014; Line et al. 2014; Zellem et al. 2014; Schwarz et al. 2015; Evans et al. 2015).”
• DISEQUILIBRIUM CARBON, OXYGEN, AND NITROGEN CHEMISTRY IN THE ATMOSPHERES OF HD 189733b AND HD 209458b (2011, background): “…little light on the source of the absorber responsible for the stratospheric thermal inversions inferred for HD 209458b and other exoplanets (e.g., Burrows et al. 2007, 2008; Knutson et al. 2008, 2009; Fortney et al. 2008a; Machalek et al. 2009, 2010; Madhusudhan & Seager 2009, 2010a; O’Donovan…”
• The 3.6-8.0 μm Broadband Emission Spectrum of HD 209458b: Evidence for an Atmospheric Temperature Inversion (2007, background): “…of an irradiated hot Jupiter (Bodenheimer et al. 2001; Showman & Guillot 2002; Bodenheimer et al. 2003; Baraffe et al. 2003; Laughlin et al. 2005a; Burrows et al. 2007a), but there are currently four planets (HD 209458b, WASP-1b, TrES-2, and TrES-4) with radii that appear to be significantly…”
• C/O RATIO AS A DIMENSION FOR CHARACTERIZING EXOPLANETARY ATMOSPHERES (2012, background): “While some highly irradiated hot Jupiters do seem to host thermal inversions (Burrows et al. 2007; Knutson et al. 2008; Christiansen et al. 2010; Madhusudhan & Seager 2010), several counterexamples to the TiO/VO hypothesis have also been reported.”
• ATMOSPHERIC CIRCULATION OF HOT JUPITERS: COUPLED RADIATIVE-DYNAMICAL GENERAL CIRCULATION MODEL SIMULATIONS OF HD 189733b and HD 209458b (2008, unknown): “For HD 209458b, we include gaseous TiO and VO opacity to see whether it allows us to explain the inference of a stratosphere fromSpitzerphotometry (Knutson et al. 2008; Burrows et al. 2007; Fortney et al. 2008).”
• THE STATISTICS OF ALBEDO AND HEAT RECIRCULATION ON HOT EXOPLANETS (2009, background): “The presence or lack of a stratospheric temperature inversion (Hubeny et al. 2003; Fortney et al. 2006; Burrows et al. 2007, 2008; Zahnle et al. 2009) on the day-sides of exoplanets has been invoked to explain a purported bi-modality in recirculation efficiency on hot Jupiters (Fortney et al. 2008).”
• NO THERMAL INVERSION AND A SOLAR WATER ABUNDANCE FOR THE HOT JUPITER HD 209458B FROM HST/WFC3 SPECTROSCOPY (2016, background): “…most serious issue for the thermal inversion hypothesis is that the Spitzer photometric bands typically used to discriminate for inversions are expected to probe similar pressure levels for solar-like composition atmospheres in chemical equilibrium (Burrows et al. 2007, 2008; Showman et al. 2009).”
• ATMOSPHERIC SULFUR PHOTOCHEMISTRY ON HOT JUPITERS (2009, background): “One suggestion is that temperature inversions are triggered by irradiation reaching a critical level that is hot enough to evaporate TiO and VO from grains, as discussed by Burrows et al. (2007), Fortney et al. (2008), and Burrows et al. (2008).”
• Transit spectrophotometry of the exoplanet HD189733b. I. Searching for water but finding haze with HST NICMOS (2009, background): “This planet also exhibits a stratospheric temperature inversion (Burrows et al. 2007; Knutson et al. 2008) thought to be caused by a strong optical absorber such as TiO (Désert et al. 2008; Hubeny et al. 2003; Fortney et al. 2008) and/or HS and S2 (Zahnle et al. 2009).”
• CAN TiO EXPLAIN THERMAL INVERSIONS IN THE UPPER ATMOSPHERES OF IRRADIATED GIANT PLANETS? (2009, background): “Infrared observations by the Spitzer Space Telescope have suggested that several giant planets have such thermal inversions, including HD 209458b (Burrows et al. 2007b; Knutson et al. 2008a), HD 149026b (Fortney et al. 2006; Burrows et al. 2008), TrES-4 (Knutson et al. 2009), XO-1b (Machalek et al.…”
• INFLATING HOT JUPITERS WITH OHMIC DISSIPATION (2010, background): “While this effect may be small for HD209458b and HD189733b, weather on hotter planets, such as Tres4b or Wasp-12b may be more intimately linked with their magnetic fields, calling for a magentohydrodynamic treatment of the atmospheric circulation.”
• A SYSTEMATIC RETRIEVAL ANALYSIS OF SECONDARY ECLIPSE SPECTRA. I. A COMPARISON OF ATMOSPHERIC RETRIEVAL TECHNIQUES (2013, methodology): “These same data have been used to infer the presence of atmospheric temperature inversions for a subset of hot Jupiters (e.g., Burrows et al. 2007, Knutson et al. 2008;2010; Forntey et al. 2008; Madhusudhan & Seager 2009; 2010).”
• On the radiative equilibrium of irradiated planetary atmospheres (2010, background): “…∫ ∞ 0 e−Z [ πθ̃(r + ∆z,Z)Z ]1/2 dZ (60) In the limit of an isothermal atmosphere,θ̃(r,Z) = 1, the integral is equal to 1 (the erf function evaluated at infinity) and the expression of the chord optical depth and height difference reduce to the relations proposed by Burrows et al. (2007a).”