Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets

Fortney, Jonathan J.; Visscher, Channon; Marley, Mark S.; Hood, Callie E.; Line, Michael R.; Thorngren, Daniel; Freedman, Richard; Lupu, Roxana

doi:10.3847/1538-3881/abc5bd

Cited by 76 publications

(106 citation statements)

References 117 publications

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“…The equilibrium temperature at periapse is ∼2500 K, comparable to classic super Hot Jupiters such as WASP-121 (Delrez et al 2016;Evans et al 2017). At apoapse, the equilibrium temperature is ∼800 K. As the planet cools down, its atmosphere will cross the equal abundance boundaries of CO/CH 4 and N 2 /NH 3 (Fortney et al 2020). Significant condensation of clouds is also expected due to the dramatic temperature change (Wakeford et al 2017).…”

Section: Discussion and Future Workmentioning

confidence: 93%

TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration

Dong

Huang

Zhou

et al. 2021

ApJL

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High-eccentricity tidal migration is a possible way for giant planets to be placed in short-period orbits. If this happens often, one would expect to catch proto hot Jupiters on highly elliptical orbits undergoing high-eccentricity tidal migration. As of yet, few such systems have been discovered. Here, we introduce TOI-3362b (TIC-464300749b), an 18.1 day, 5 M Jup planet orbiting a main-sequence F-type star that is likely undergoing higheccentricity tidal migration. The orbital eccentricity is 0.815 -+ 0.032 0.023 . With a semimajor axis of 0.153 -+ 0.003 0.002 au, the planet's orbit is expected to shrink to a final orbital radius of 0.051 -+ 0.006 0.008 au after complete tidal circularization. Several mechanisms could explain the extreme value of the planet's eccentricity, such as planet-planet scattering and secular interactions. Such hypotheses can be tested with follow-up observations of the system, e.g., measuring the stellar obliquity and searching for companions in the system with precise, long-term radial-velocity observations. The variation in the planet's equilibrium temperature as it orbits the host star and the tidal heating at periapse make this planet an intriguing target for atmospheric modeling and observation. Because the planet's orbital period of 18.1 days is near the limit of TESS's period sensitivity, even a few such discoveries suggest that proto hot Jupiters may be quite common.

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Section: Discussion and Future Workmentioning

confidence: 93%

TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration

Dong

Huang

Zhou

et al. 2021

ApJL

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“…Note that temperature also affects the thermochemical equilibrium that controls the lower boundary conditions for the main species. Thus, results in further modifications of the main abundances depending on the elemental composition and Tint value assumed (Fortney et al 2020). The disequilibrium temperature profile results in higher abundances for H2O, CH4 and NH3 in the photosphere region, while the H2 to H transition starts at lower pressures near 0.1 mbar.…”

Section: Hd 189733 Bmentioning

confidence: 98%

Impact of photochemical hazes and gases on exoplanet atmospheric thermal structure

Lavvas

Arfaux

2021

Monthly Notices of the Royal Astronomical Society

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We investigate the impact of photochemical hazes and disequilibrium gases on the thermal structure of hot-Jupiters, using a detailed 1-D radiative-convective model. We find that the inclusion of photochemical hazes results in major heating of the upper and cooling of the lower atmosphere. Sulphur containing species, such as SH, S2 and S3 provide significant opacity in the middle atmosphere and lead to local heating near 1 mbar, while OH, CH, NH, and CN radicals produced by the photochemistry affect the thermal structure near 1 μbar. Furthermore we show that the modifications on the thermal structure from photochemical gases and hazes can have important ramifications for the interpretation of transit observations. Specifically, our study for the hazy HD 189733 b shows that the hotter upper atmosphere resulting from the inclusion of photochemical haze opacity imposes an expansion of the atmosphere, thus a steeper transit signature in the UV-Visible part of the spectrum. In addition, the temperature changes in the photosphere also affect the secondary eclipse spectrum. For HD 209458 b we find that a small haze opacity could be present in this atmosphere, at pressures below 1 mbar, which could be a result of both photochemical hazes and condensates. Our results motivate the inclusion of radiative feedback from photochemical hazes in general circulation models for a proper evaluation of atmospheric dynamics.

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“…A quantitative description of this behavior is provided below. Note that the quench point depends on the strength of vertical mixing and the deep-atmosphere temperature depends on the thermal history of the planet, and so the detail behavior may be complex 56 . water is stable.…”

Section: Methodsmentioning

confidence: 99%

“…The biggest uncertainty is probably the temperature at the ∼ 100-bar pressure level in the massive-atmosphere scenarios, which may be affected by ad hot heating mechanisms such as tidal heating. Detailed models of the interior temperature and mixing may further constrain this uncertainty 56 .…”

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confidence: 99%

Unveiling shrouded oceans on temperate sub-Neptunes via transit signatures of solubility equilibria vs. gas thermochemistry

Hu¹,

Damiano²,

Scheucher³

et al. 2021

Preprint

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The recent discovery and initial characterization of sub-Neptune-sized exoplanets that receive stellar irradiance of approximately Earth's raised the prospect of finding habitable planets in the coming decade. Some of these temperate planets may support liquid water oceans, if they do not have massive H2/He envelopes and are thus not too hot at the bottom of the envelopes. For planets larger than Earth, and especially planets in the 1.7-3.5 R_Earth population, the mass of the H2/He envelope is typically not sufficiently constrained to assess the potential habitability. Here we show that the solubility equilibria vs. thermochemistry of carbon and nitrogen gases results in observable discriminators between small H2 atmospheres vs. massive ones. On temperate sub-Neptunes, the condition to form a liquid-water ocean and that to achieve the thermochemical equilibrium are mutually exclusive. The dominant carbon and nitrogen gases are typically CH4 and NH3 due to thermochemical recycling in a massive atmosphere of a temperate planet, and those in a small atmosphere overlying a liquid-water ocean are most likely CO2 and N2, followed by CO and CH4 produced photochemically. NH3 is depleted in the small atmosphere by dissolution into the liquid-water ocean. These gases lead to distinctive features in the planet's transmission spectrum, and a moderate number of repeated transit observations with the James Webb Space Telescope should readily tell apart a small atmosphere vs. a massive one via these spectral features on planets like K2-18 b. This method thus provides a way to use near-term facilities to constrain the atmospheric mass and habitability of temperate sub-Neptune exoplanets.

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Beyond Equilibrium Temperature: How the Atmosphere/Interior Connection Affects the Onset of Methane, Ammonia, and Clouds in Warm Transiting Giant Planets

Cited by 76 publications

References 117 publications

TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration

TOI-3362b: A Proto Hot Jupiter Undergoing High-eccentricity Tidal Migration

Impact of photochemical hazes and gases on exoplanet atmospheric thermal structure

Unveiling shrouded oceans on temperate sub-Neptunes via transit signatures of solubility equilibria vs. gas thermochemistry

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