Rayleigh scattering in the transit spectrum of HD 189733b

By A. D. Étangs, F. Pont, A. Vidal-Madjar, D. Sing. 2008

337 citations recorded by the source corpus.

The transit spectrum of the exoplanet HD 189733b has recently been obtained between 0.55 and 1.05 µm. Here we present an analysis of this spectrum. We develop first-order equations to interpret absorption spectra. In the case of HD 189733b, we show that the observed slope of the absorption as a function of wavelength is characteristic of extinction proportional to the inverse of the fourth power of the wavelength (∝λ −4 ). Assuming an extinction dominated by Rayleigh scattering, we derive an atmospheric temperature of 1340 ± 150 K. If molecular hydrogen is responsible for the Rayleigh scattering, the atmospheric pressure at the planetary characteristic radius of 0.1564 stellar radius must be 410 ± 30 mbar. However the preferred scenario is scattering by condensate particles. Using the Mie approximation, we find that the particles must have a low value for the imaginary part of the refraction index. We identify MgSiO3 as a possible abundant condensate whose particle size must be between ∼10 −2 and ∼10 −1 µm. For this condensate, assuming solar abundance, the pressure at 0.1564 stellar radius is found to be between a few microbars and few millibars, and the temperature is found to be in the range 1340–1540 K, and both depend on the particle size.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/592ca3ddeeb2af501094b881ff50398d73009f3f

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. D. Sing
5. D. Deming
6. J. D'esert
7. D. Charbonneau
8. H. Knutson

In Instrumentation

1. Jon Fortney
2. N. Madhusudhan
3. A. Showman
4. D. Sing
5. H. Knutson
6. J. D'esert
7. D. Charbonneau
8. D. Deming

Citations in the corpus

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• THE FLAT TRANSMISSION SPECTRUM OF THE SUPER-EARTH GJ1214b FROM WIDE FIELD CAMERA 3 ON THE HUBBLE SPACE TELESCOPE (2011, methodology): “This is unlike the case of the hot Jupiter HD189733b, where the uniform decrease in transit depth from 0.3 to 1 µm (Pont et al. 2008; Lecavelier Des Etangs et al. 2008; Sing et al. 2011) and perhaps to as far as 3.6 µm (see Sing et al. 2009; Désert et al. 2009) has been convincingly attributed to…”
• Temperature–pressure profile of the hot Jupiter HD 189733b from HST sodium observations: detection of upper atmospheric heating (2012, methodology): “Since the temperature derived from the Rayleigh slope by Lecavelier des Etangs et al. (2008a) is the same as the fit obtained here by assuming that the whole signal in the wings is due to sodium, the presence of a Rayleigh component in our signal does not affect our calculated atmospheric T -”
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• DETECTION OF H2O AND EVIDENCE FOR TiO/VO IN AN ULTRA-HOT EXOPLANET ATMOSPHERE (2016, methodology): “Cambridge, Mass.: Smithsonian Astrophysical Observatory, 1993., 13 Lecavelier Des Etangs, A., Pont, F., Vidal-Madjar, A., & Sing, D. 2008, A&A, 481, L83 Mandel, K. & Agol, E. 2002, ApJ, 580, L171 Markwardt, C. B. 2009, in Astronomical Society of the Pacific Conference Series, Vol. 411, Astronomical ”
• Evaporation of the planet HD 189733b observed in H I Lyman-α (2010, methodology): “…have been used to develop several theoretical models to explain and characterize the evaporation processes (Lammer et al. 2003; Lecavelier des Etangs et al. 2004, 2007, 2008a; Baraffe et al. 2004, 2005, 2006; Yelle 2004, 2006; Jaritz et al. 2005; Tian et al. 2005; Garćıa-Muñoz 2007;…”
• THE INFLUENCE OF NONUNIFORM CLOUD COVER ON TRANSIT TRANSMISSION SPECTRA (2015, methodology): “For these illustrative calculations, we assume that the effective radius of the cloudy planet is 5 scale heights larger than that of the clear, corresponding to clouds having an opacity ≈ 150 times higher than the gas opacity in the bandpass of observation (equation 1, Lecavelier Des Etangs et al. 2”
• HST hot-Jupiter transmission spectral survey: detection of potassium in WASP-31b along with a cloud deck and Rayleigh scattering (2014, methodology): “To further characterize and assess the significance of the slope, we fit the near-UV transmission spectrum assuming an atmospheric opacity with an effective extinction (scattering+absorption) cross-section which follows a power law of index α, i.e. σ = σ(λ/λ0) α following Lecavelier des Etangs et al”
• OBSERVATIONS OF MASS LOSS FROM THE TRANSITING EXOPLANET HD 209458b (2010, background): “However, Lecavelier des Etangs et al. (2008b) argued that the observed Lyman-α profile and the high-velocity hydrogen atoms can be simply explained by stellar radiation pressure and the ENA explanation required a peculiar stellar wind model.”
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