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Probing Dynamical Cloud Formation in Exoplanet Atmospheres

Presentation #624.31 in the session Planetary Atmospheres - Hot Jupiters.

Published onApr 03, 2024
Probing Dynamical Cloud Formation in Exoplanet Atmospheres

Cloud formation and the constituent make-up of clouds is one of the dominant uncertainties in exoplanet atmospheres. While the signature of clouds in exoplanet transmission spectra is to mute spectral features, exoplanet phase curves of extrasolar planets may offer a new way to probe exoplanet atmospheres. Due to the nature of an eccentric orbit, the total irradiation at the top of the planetary atmosphere is variable over the duration of the orbit, periodically raising and lowering its equilibrium temperature. If this equilibrium temperature at the top of the atmosphere crosses a molecular condensation point, we may periodically see the condensation and evaporation of clouds at that level in the atmosphere, obscuring the deeper warmer layers of the atmosphere and lowering the total system flux. In this poster I will show preliminary results searching for this type of signature in the Kepler dataset, with a particular focus on KOI 614.01 and KOI 469.01. Their phase curves show variations that cannot be explained via effects like Doppler beaming, ellipsoidal variations, or (bond albedo) reflection. In the case of KOI 614.01, extant radial velocity observations combined with the Kepler phase curve show that the total flux from the system resembles a stepfunction, increasing by 25 ppm at an equilibrium temperature of approximately 1000 Kelvin over a duration of approximately 8 hours. We suggest that KCl cloud condensation and evaporation may be the origin of this effect and in this poster describe our current modeling challenges in describing this effect and prospects for uncovering additional targets in Kepler data and obtaining robust eccentricity measurements.

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