Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low‐Mass Dwarf Stars. II. Sulfur and Phosphorus

Visscher, Channon; Lodders, K.; Fegley, B.

doi:10.1086/506245

Cited by 259 publications

(293 citation statements)

References 61 publications

(97 reference statements)

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“…The 3D simulations described here, as in Showman et al (2009), use 30 wavelength bins (see Showman et al 2009 for more details). For a given metallicity, the chemical mixing ratios and opacities are calculated assuming local chemical equilibrium as a function of local temperature and pressure, accounting properly for depletion of gas-phase species via condensation, follow K. Lodders and collaborators (Lodders 1999;Lodders & Fegley 2002;Lodders 2002;Visscher et al 2006;Lodders 2010). Note, however, that we include only gas-phase opacity; any opacity from clouds/hazes is neglected.…”

Section: Methods: Atmosphere Modelsmentioning

confidence: 99%

Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres

Fortney

Shabram

Showman

et al. 2010

ApJ

306

415

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We compute models of the transmission spectra of planets HD 209458b, HD 189733b, and generic hot Jupiters. We examine the effects of temperature, surface gravity, and metallicity for the generic planets as a guide to understanding transmission spectra in general. We find that carbon dioxide absorption at 4.4 and 15 μm is prominent at high metallicity, and is a clear metallicity indicator. For HD 209458b and HD 189733b, we compute spectra for both one-dimensional and three-dimensional model atmospheres and examine the differences between them. The differences are usually small, but can be large if atmospheric temperatures are near important chemical abundance boundaries. The calculations for the three-dimensional atmospheres, and their comparison with data, serve as constraints on these dynamical models that complement the secondary eclipse and light curve data sets. For HD 209458b, even if TiO and VO gases are abundant on the dayside, their abundances can be considerably reduced on the cooler planetary limb. However, given the predicted limb temperatures and TiO abundances, the model's optical opacity is too high. For HD 189733b we find a good match with some infrared data sets and constrain the altitude of a postulated haze layer. For this planet, substantial differences can exist between the transmission spectra of the leading and trailing hemispheres, which are an excellent probe of carbon chemistry. In thermochemical equilibrium, the cooler leading hemisphere is methane-dominated, and the hotter trailing hemisphere is COdominated, but these differences may be eliminated by non-equilibrium chemistry due to vertical mixing. It may be possible to constrain the carbon chemistry of this planet, and its spatial variation, with James Webb Space Telescope.

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Section: Methods: Atmosphere Modelsmentioning

confidence: 99%

Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres

Fortney

Shabram

Showman

et al. 2010

ApJ

306

415

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“…The code was first developed for Titan's atmosphere ) and since then has been extensively used for the study of giant planets (Marley et al 1996), brown dwarfs (Burrows et al 1997;Marley et al 2002), and hot Jupiters (Fortney et al , 2008Showman et al 2009). We use the opacities described in Freedman et al (2008), including more recent updates (Freedman et al 2014), and the molecular abundances described by Lodders & Fegley (2002) and Visscher et al (2006).…”

Section: Radiative Transfer Modelmentioning

confidence: 99%

Transitions in the Cloud Composition of Hot Jupiters

Parmentier

Fortney

Showman

et al. 2016

ApJ

309

436

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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.

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“…The methane line lists have been updated using Yurchenko et al (2014), and the alkali line lists have been updated to use the results from Allard et al (2005). Chemical equilibrium grids based on previous thermochemical models (Lodders 1999(Lodders , 2002Lodders & Fegley 2002Visscher et al 2006Visscher et al , 2010Visscher 2012;Moses et al 2013) have been revised and extended to include higher metallicities. These updates will be described in detail in a set of upcoming papers that focus on the new model grid.…”

Section: Atmosphere Modelsmentioning

confidence: 99%

THE LEECH EXOPLANET IMAGING SURVEY: CHARACTERIZATION OF THE COLDEST DIRECTLY IMAGED EXOPLANET, GJ 504 b, AND EVIDENCE FOR SUPERSTELLAR METALLICITY*

Skemer

Morley

Zimmerman

et al. 2016

ApJ

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As gas giant planets and brown dwarfs radiate away the residual heat from their formation, they cool through a spectral type transition from L to T, which encompasses the dissipation of cloud opacity and the appearance of strong methane absorption. While there are hundreds of known T-type brown dwarfs, the first generation of directly imaged exoplanets were all Ltype. Recently, Kuzuhara et al. announced the discovery of GJ 504 b, the first T dwarf exoplanet. GJ 504 b provides a unique opportunity to study the atmosphere of a new type of exoplanet with a ∼500 K temperature that bridges the gap between the first directly imaged planets (∼1000 K) and our own solar systemʼs Jupiter (∼130 K). We observed GJ 504 b in three narrow L-band filters (3.71, 3.88, and 4.00 μm), spanning the red end of the broad methane fundamental absorption feature (3.3 μm) as part of the LBTI Exozodi Exoplanet Common Hunt (LEECH) exoplanet imaging survey. By comparing our new photometry and literature photometry with a grid of custom model atmospheres, we were able to fit GJ 504 bʼs unusual spectral energy distribution for the first time. We find that GJ 504 b is wellfit by models with the following parameters:.12, cloud opacity parameter of f sed =2-5, R=0.96±0.07 R Jup , and log(L)=−6.13±0.03 L e , implying a hot start mass of 3-30 M jup for a conservative age range of 0.1-6.5 Gyr. Of particular interest, our model fits suggest that GJ 504 b has a superstellar metallicity. Since planet formation can create objects with nonstellar metallicities, while binary star formation cannot, this result suggests that GJ 504 b formed like a planet, not like a binary companion.

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Atmospheric Chemistry in Giant Planets, Brown Dwarfs, and Low‐Mass Dwarf Stars. II. Sulfur and Phosphorus

Cited by 259 publications

References 61 publications

Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres

Transmission Spectra of Three-Dimensional Hot Jupiter Model Atmospheres

Transitions in the Cloud Composition of Hot Jupiters

THE LEECH EXOPLANET IMAGING SURVEY: CHARACTERIZATION OF THE COLDEST DIRECTLY IMAGED EXOPLANET, GJ 504 b, AND EVIDENCE FOR SUPERSTELLAR METALLICITY*

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