TRANSITIONS IN THE CLOUD COMPOSITION OF HOT JUPITERS

By V. Parmentier, Jon Fortney, A. Showman, C. Morley, M. Marley. 2016

171 citations recorded by the source corpus.

Over a large range of equilibrium temperatures, clouds shape the transmission spectrum of hot Jupiter atmospheres, yet their composition remains unknown. Recent observations show that the Kepler light curves of some hot Jupiters are asymmetric: for the hottest planets, the light curve peaks before secondary eclipse, whereas for planets cooler than ∼1900 K, it peaks after secondary eclipse. We use the thermal structure from 3D global circulation models to determine the expected cloud distribution and Kepler light curves of hot Jupiters. We demonstrate that the change from an optical light curve dominated by thermal emission to one dominated by scattering (reflection) naturally explains the observed trend from negative to positive offset. For the cool planets the presence of an asymmetry in the Kepler light curve is a telltale sign of the cloud composition, because each cloud species can produce an offset only over a narrow range of effective temperatures. By comparing our models and the observations, we show that the cloud composition of hot Jupiters likely varies with equilibrium temperature. We suggest that a transition occurs between silicate and manganese sulfide clouds at a temperature near 1600 K, analogous to the L/T transition on brown dwarfs. The cold trapping of cloud species below the photosphere naturally produces such a transition and predicts similar transitions for other condensates, including TiO. We predict that most hot Jupiters should have cloudy nightsides, that partial cloudiness should be common at the limb, and that the dayside hot spot should often be cloud-free.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/b28def8509827cecba8dd1301743b0256e218a70

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In Astronomy and Astrophysics

1. N. Madhusudhan
2. Jon Fortney
3. A. Showman
4. M. Line
5. V. Parmentier
6. D. Sing
7. M. Marley
8. J. D'esert

Citations in the corpus

• From thermal dissociation to condensation in the atmospheres of ultra hot Jupiters: WASP-121b in context (2018, methodology): “This method, similar to the calculation of Fortney et al. (2006) and Parmentier et al. (2016), naturally takes into account geometrical effects such as limb darkening.”
• A Population Study of Gaseous Exoplanets (2017, methodology): “Population synthesis studies based on formation scenarios or statistics from the Kepler Space mission suggest a great diversity in the exoplanet population (e.g. Fortney et al. 2013; Lopez & Fortney 2014; Rogers 2015; Parmentier et al. 2016).”
• Exoplanetary Atmospheres: Key Insights, Challenges, and Prospects (2019, methodology): “tion, the effects of clouds have also been inferred through optical phase curves of transiting exoplanets (64, 242, 91, 200) as well as a few reflection spectra (75, 175).”
• Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, methodology): “…asymmetry is expected to produce large gradients in temperature, chemistry, and cloud coverage with longitude (Showman et al. 2009; Kataria et al. 2016; Parmentier et al. 2016), and provides an opportunity to learn about atmospheric dynamics in a very different regime from the Solar System planets.”
• HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b (2017, background): “These observations can be used to constrain the nature and particle size of the opacity source (e.g., Wakeford & Sing 2015; Sing et al. 2016; Parmentier et al. 2016; Wakeford et al. 2017).”
• SPITZER PHASE CURVE CONSTRAINTS FOR WASP-43b AT 3.6 AND 4.5 μm (2016, background): “However, cloud inhomogeneities (or patchiness) can weaken this effect (Parmentier et al. 2016).”
• HD 209458b in new light: evidence of nitrogen chemistry, patchy clouds and sub-solar water (2017, background): “This view was further reinforced by Sing et al. (2016), who used transmission spectra of ten hot Jupiters to claim that clouds and hazes, not sub-solar H2O, sufficiently explain the spectra.”
• H− Opacity and Water Dissociation in the Dayside Atmosphere of the Very Hot Gas Giant WASP-18b (2018, background): “Vertical cold trapping of TiO can act to remove this species from the atmosphere of hot Jupiters (e.g., Désert et al. 2008), but not for planets with equilibrium temperatures above ∼1900 K (Parmentier et al. 2016).”