Cloud Base Signature in Transmission Spectra of Exoplanet Atmospheres

Abstract

We present an analytical model for the transmission spectrum of a transiting exoplanet, showing that a cloud base can produce an observable inflection point in the spectrum. The wavelength and magnitude of the inflection can be used to break the degeneracy between the atmospheric pressure and the abundance of the main cloud material, however, the abundance still depends on cloud particle size. An observed inflection also provides a specific point on the atmospheric P-T profile, giving us a "thermometer" to directly validate or rule out postulated cloud species. We apply the model to the transit spectrum of HD 189733b.

References in corpus (3)

• Detection of atmospheric haze on an extrasolar planet: The 0.55 - 1.05 micron transmission spectrum of HD189733b with the Hubble Space Telescope
• Rayleigh scattering in the transit spectrum of HD 189733b
• Hubble Space Telescope times-series photometry of the planetary transit of HD189733: no moon, no rings, starspots

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