This session aims to invite recent progress in exoplanet atmosphere characterisation based on a combination of observation and modelling. The session focusses on cloud and gas-phase chemistry modelling, the modelling of magnetic coupling in atmospheres and how these have and can be observed. Contributions working at the cross-over of solar system and exoplanet sciences are particularly welcomed.
This session is triggered by the recent CHEOPS atmosphere interpretation activities on incorporating complex 3D modelling in their data interpretation. This session is part of the PLATO WP/WG activities for exoplanet gas giants.
Organisational aspects:
We plan to assure a diverse program as well as a diversity of speakers according to the EGU EDI labels. The program shall foster exchange by leaving enough time for questions and answers. We further plan to involve young researchers into the session handling (following the EANA example).
I will present several recent discoveries related to exoplanetary atmospheres, made possible by the combination of cutting-edge observations from the James Webb Space Telescope (JWST) and an advanced multidimesnsional modeling technique. Our methodology integrates both forward (theoretically-driven) and retrieval (observationally-driven) approaches, combining theoretical, statistical, and numerical models with mapping techniques to constrain the fundamental properties of exoplanetary atmospheres, such as their chemical composition, temperature structure, dynamics, and overall climate.The discoveries I will highlight include the first detection of mineral clouds on the nightside of an exoplanet, the first inference of an exoplanet’s magnetic field, and the first spatially resolved dayside structure of an exoplanetary atmosphere. These breakthrough results mark significant advancements in our understanding of exoplanet atmospheres.
How to cite: Blecic, J.: From Mineral Clouds to Magnetic Field: Groundbreaking Discoveries in Exoplanetary Atmospheres with JWST, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20271, https://doi.org/10.5194/egusphere-egu25-20271, 2025.
The most recent JWST observations of WASP-39b and WASP-107b show that a comparison of the morning and evening atmosphere of cloudy hot Jupiters is possible by very precise monitoring of transit ingress and egress with next generation space telescopes. In addition, extensive modelling efforts have demonstrated that gas giants orbiting different host stars should exhibit different degrees of morning-evening asymmetries, where cloud formation is predicted to amplify existing hydrodynamically driven asymmetries in the local thermodynamics at each limb.
The PLATO space mission to be launched 2026 has the potential to yield detailed comparison between the morning and evening terminator of hot Jupiter in the optical wavelength range. In the optical, cloud scattering properties are expected to dominate as already outlined with Kepler data. As such these observations would be highly complementary to JWST IR observations that mainly probe differences in molecular chemistry across the limbs.
We explore in how far PLATO photometry may be used to study such terminator asymmetries driven by differences in cloud coverage as follow-up to Grenfell et al. 2020. We use a grid of 60 3D GCMs using ExoRad (Carone+2020, Schneider, Carone+2023) for gas giants orbiting M, G, F, K and A stars at various orbital distances such that their global temperature ranges from 600K - 2600K. For each of these models, cloud formation and gas-phase chemistry is calculated subsequently. This work is part of our science support efforts within the PLATO WPs 116700 and 116800.
How to cite: Carone, L., Helling, C., Gernjak, S., Kiefer, S., Janz, T., and Hanna Leitner, H.: Observing Transit morning-evening asymmetries with PLATO, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3251, https://doi.org/10.5194/egusphere-egu25-3251, 2025.
Ultra-hot Jupiters (UHJs) present unique laboratories for studying extreme atmospheric dynamics and their interactions with planetary magnetic fields with space missions like CHEOPS, JWST, and PLATO. WASP-18 b, a UHJ with an equilibrium temperature exceeding 2400 K, orbits an F6-type star at a close distance of 0.02 AU. Under these conditions, the atmosphere undergoes substantial thermal ionisation, resulting in partial ionisation that may interact with the planet’s internal magnetic field.
This study explores the influence of magnetic drag on the atmospheric dynamics of WASP-18 b. By incorporating an approximation of the Lorentz force into the General Circulation Model (GCM) ExoRad, we analyse how this mechanism impacts the planet’s atmospheric dynamics and compare our treatment to previous GCMs with active magnetic drag. Furthermore, the observational implications of JWST and CHEOPS data are discussed in the context of the magnetic field's influence on the atmosphere. This work is part of our science support efforts within the PLATO WPs 116700 and 116800.
How to cite: Blöcker, A., Carone, L., and Helling, C.: Analysing Magnetic Drag in the Atmosphere of WASP-18 b Using ExoRad, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16871, https://doi.org/10.5194/egusphere-egu25-16871, 2025.
Over the past two decades, a coherent picture has emerged of the atmospheric dynamics of hot Jupiters from a combination of three-dimensional general circulation models (GCMs) and astronomical observations. This paradigm consists of hot Jupiters being spin-synchronized due to their close-in orbit, with a resulting large day-to-night irradiation gradient driving a day-to-night temperature contrast. This day-to-night temperature contrast in turn raises day-to-night pressure gradients that are balanced by a circulation with wind speeds on the order of km/s. The dominant feature of this circulation is a superrotating equatorial jet, maintained by eddy-mean flow interactions that pump momentum into the jet. In this work, I explore the dependence of this circulation paradigm on the initial thermal and dynamical conditions in atmospheric circulation models of hot Jupiters. To do so, I conduct MITgcm simulations of the atmospheric circulation of hot Jupiters with both varying initial wind directions and initial temperature profiles. I find that the results are ubiquitously insensitive to the initial conditions, implying that the current paradigm of hot Jupiter circulation exhibits at most limited hysteresis. I demonstrate that there is a single characteristic wind speed of hot Jupiters for given planetary and atmospheric parameters using an idealized scaling theory, and discuss implications for the interpretation of hot Jupiter observations.
How to cite: Komacek, T.: Testing the standard model of hot Jupiter atmospheric circulation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5965, https://doi.org/10.5194/egusphere-egu25-5965, 2025.
For the first time, an atmosphere has been confirmed on a rocky exoplanet, which is the hot super-Earth 55 Cnc e. Its atmosphere shows strong variability, for which cloud formation above a molten crust could be one possible explanation. If cloud formation takes place in a planetary atmosphere this affects the gas composition, its cooling and heating rates and it can dim or lead to spectral features.
We have run cloud formation models on a grid of atmospheres of various compositions to investigate which type of cloud we could expect on a planet like 55 Cnc e. Our models combine radiative transfer with equilibrium chemistry of the gaseous and condensed phases, vertical mixing of condensable species, sedimentation, nucleation and coagulation. In this talk I will present the results of our grid calculation focusing on the type of clouds in hot super-Earths and sub-Neptunes, the conditions for these clouds to form, their spectroscopic features and their potential detectability with JWST and future instruments.
How to cite: Janssen, L.: Can we find clouds in atmospheres of hot rocky exoplanets ? , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2540, https://doi.org/10.5194/egusphere-egu25-2540, 2025.
The ultra-short period super Earth 55 Cancri e offers a unique opportunity to study a small exoplanet and its potential atmosphere. Despite extensive observation, however, the nature of 55 Cancri e’s atmosphere is still poorly understood. These observational challenges are made worse by a lack of clear theoretical predictions for the atmospheric circulations of hot rocky exoplanets. So far, few 3D models with realistic radiative transfer have been applied to the high-temperature regime relevant for 55 Cancri e, largely because most 3D general circulation model (GCM) radiative transfer codes break down at high temperatures. Here we develop custom correlated-k coefficients from the ExoMol line list dataset. Then we perform 3D GCM simulations with non-grey radiative transfer to model the atmosphere on 55 Cancri e. Comparing our simulations to recent eclipse spectra from JWST MIRI (Hu et al. 2024), we suggest the atmosphere of 55 Cancri e is more likely to be thick and carbon dioxide rich, a different conclusion than that based on 1D retrieval models. In addition, our clearsky simulations suggest that 55 Cancri e’s atmosphere should exhibit time variability. However, the simulated variability is much weaker than that seen in observations from Spitzer, CHEOPS, and JWST. Our work rules out large-scale atmospheric dynamics as the cause of 55 Cancri e’s observed variability, favoring other mechanisms. More broadly, our work presents a new non-grey 3D GCM for hot rocky exoplanets and provides a more realistic framework for investigating the atmosphere of ultra-hot exoplanets like 55 Cancri e.
How to cite: Zhan, R. and Koll, D.: Modeling the Atmosphere of 55 Cancri e with a Non-grey General Circulation Model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4751, https://doi.org/10.5194/egusphere-egu25-4751, 2025.
Exoplanets on close-in orbits are subject to intense X-ray and ultraviolet (XUV) radiation from their host stars, which can lead to significant atmospheric heating and even thermal escape. However, XUV is not the sole source of energy deposition in these atmospheres. Ohmic heating can also be acting in the upper atmosphere of exoplanets, and has been underlooked so far.
Indeed, close-in exoplanets orbit around their host star by experiencing the influence of the stellar wind, where variations in the ambient magnetic field can induce electric currents in their upper atmosphere. These electric currents can dissipate into heat, depending on the atmosphere conductive properties, via a process known as Ohmic dissipation. We have developed a simplified formalism to quantify this Ohmic heating, and assess its significance compared to ‘classical' XUV heating. We have applied our formalism to idealised atmospheric profiles, as well as to cutting edge photochemical models of Trappist-1 b and π Men c. Our results show that Ohmic heating strongly depends on both the shape and strength of the conductivity profile in the upper atmospheres. In the most extreme cases, we show that Ohmic heating can reach up to 10−3 erg s−1 cm−3, i.e. volumetric heating rates comparable to and even surpassing standard photochemical heating rates.
These findings suggest that Ohmic heating could significantly affect the thermal evolution and atmospheric escape processes of hot exoplanets. In addition, this strong heating is associated with a screening of the external time-varying field. We identify the parameter regimes where the upper atmosphere can act as a shield that prevents external magnetic fields from penetrating deeper into the atmosphere or the planet's interior, thereby diminishing the potential magnetic coupling of deep atmospheres with external magnetic transients.
How to cite: Strugarek, A., García Muñoz, A., Brun, A. S., and Paul, A.: Heating up the upper atmosphere of close-in planets due to external time-varying magnetic fields, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5207, https://doi.org/10.5194/egusphere-egu25-5207, 2025.
The study of exoplanets orbiting white dwarfs is a largely unexplored field. With WD 0806-661 b, we present the first deep dive into the atmospheric physics and chemistry of a cold exoplanet around a white dwarf. We observed WD 0806-661 b using JWST's Mid-InfraRed Instrument Low-Resolution Spectrometer (MIRI-LRS), covering the wavelength range from 5 to 12 microns, and the Imager, providing us with 12.8, 15, 18 and 21 microns photometric measurements. We carried out a robust data reduction of those datasets, tackling second-order effects to ensure a reliable retrieval analysis. Using the TauREx retrieval code, we inferred the pressure-temperature structure, atmospheric chemistry, mass, and radius of the planet. The spectrum of WD 0806-661 b is shaped by molecular absorption of water, ammonia, and methane, consistent with a cold Jupiter atmosphere, allowing us to retrieve their abundances. From the mixing ratio of water, ammonia, and methane we derive C/O, C/N and N/O and the ratio of detected metals as proxy for metallicity. We also derive upper limits for the abundance of CO and CO2 which were not detected by our retrieval models. While our interpretation of WD 0806-661 b's atmosphere is mostly consistent with our theoretical understanding, some results - such as the lack of evidence for water clouds, an apparent increase in the mixing ratio of ammonia at low pressure, or the retrieved mass at odds with the supposed age - remain surprising and require follow-up observational and theoretical studies to be confirmed.
How to cite: Voyer, M., Changeat, Q., and Lagage, P.-O.: MIRI-LRS spectrum of a cold exoplanet around a white dwarf: water, ammonia, and methane measurements., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2157, https://doi.org/10.5194/egusphere-egu25-2157, 2025.
How to cite: Shivkumar, H.: Diving into the atmospheres of young planets through the lens of JWST, HST and CHEOPS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21748, https://doi.org/10.5194/egusphere-egu25-21748, 2025.
Jupiter, the largest planet in our solar system, serves as a crucial model for understanding the giant exoplanets and their atmospheres. While its upper tropospheric chemical composition is well-known, the nature and structure of its clouds remain elusive. To unveil them planetary scientists rely heavily on theoretical models and remote sensing data, as in the exoplanets field.
Traditional models, based on equilibrium cloud condensation (ECC) theory, are highly sensitive to input parameters such as the pressure-temperature profile and the chemical composition of the atmosphere. In the case of Jupiter, ECCMs predict the existence of distinct cloud layers, with the uppermost being composed of pure ammonia ice. More sophisticated models, like the Ackerman-Morley model (2001), incorporate turbulent diffusion and sedimentation, providing more realistic cloud densities and particle sizes. However, these models often neglect such crucial factors as the effects of atmospheric photochemistry and still rely on assumptions about the nature of condensed species. Remote sensing data can be used to retrieve cloud properties, but this process is highly complex and computationally expensive. For these reasons having a priori knowledge about some parameters and a large quantity of data acquired by different instruments is important to characterize the clouds and aerosols, both for planets and exoplanets.
Therefore, in this contribution, we briefly summarize the most important findings about Jovian clouds and aerosols obtained from an analysis of the data acquired by the JIRAM/Juno and NIRSpec/JWST instruments, as well as their implications for the study of giant exoplanets’ clouds.
Juno data suggest that theoretical cloud condensation models are not able to represent disk-averaged spectra of Jupiter, but they work well in the case of strong convective events and/or plumes; the presence of an extended layer of small reflecting particles (haze), not included in ECCMs, is also needed to obtain reasonable fits. Juno and JWST both suggest that the typical Jovian clouds are probably composed of materials that are the result of both photochemical processes in the upper troposphere and stratosphere, together with convection and condensation of volatile species in the lower troposphere. The optical properties of this unknown material can be approximated in the 2-3 micron range with similar refractive index spectra to those of Titan’s tholins, implying the presence of N-H stretch bonds within the aerosols of Jupiter’s clouds.
These findings lead to the following conclusions: (1) ECC and Ackerman-Marley models can (and should) be used as a first approximation to model clouds, bearing in mind that reality can be more complex because of phenomena like photochemistry; (2) modeling planetary clouds is extremely degenerate even if the most of the chemical and thermal structures are well known; therefore, it is essential to use iterative approaches and efficient radiative transfer suites; efficiency, however, should not sacrifice accuracy in the multiple scattering computations; (3) new laboratory measurements of ‘tholin-like materials’ optical constants are needed to improve atmospheric retrievals for both planets and exoplanets.
How to cite: Biagiotti, F., Grassi, D., Guillot, T., Atreya, S. K., Fletcher, L. N., Irwin, P., Piccioni, G., Mura, A., de Pater, I., Fouchet, T., King, O. R. T., Roman, M. T., Harkett, J., Melin, H., Toogood, S., Orton, G., Tosi, F., Plainaki, C., Sindoni, G., and Bolton, S. and the JIRAM & JWST ERS1373 teams: Constraining Exoplanetary Clouds with Jupiter Observations: Insights from Juno & JWST, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17760, https://doi.org/10.5194/egusphere-egu25-17760, 2025.
Since the discovery in 1995 of the first exoplanet orbiting a solar-type star, more than 5,500 exoplanets have been identified, revealing a remarkable diversity of exoplanetary systems. While many of their physical parameters are now well understood, the characterisation of exoplanetary magnetic fields remains largely unexplored, despite its critical role in atmospheric retention. To better understand exoplanetary magnetic fields, star-planet magnetic interactions present a promising avenue of investigation. Such interactions have been observed in HD 189733 which features a hot Jupiter discovered in 2005 with an atmosphere composed of H2O, CO, CH4, CO2, and Na. This system is therefore ideal for studying magnetic coupling in exoplanetary atmospheres, by better understanding star-planet magnetic interactions.
The poster presents a stellar wind model that simulates the theoretical power generated by the magnetic interactions between a star and its planet in the HD 189733 system. Two versions of the model are discussed: a polytropic version, and a more sophisticated version in which the stellar wind is heated and accelerated by Alfvén waves. These same waves can also be excited by the presence of a planet when it is sufficiently close to its star (within the so-called Alfvén surface), propagating towards the star and forming what are known as “Alfvén wings”. Star-planet magnetic interactions can only occur when the planet's orbit falls within the theoretical surface delimited by these wings.
The results of the HD 189733 system models have revealed that the planetary orbit of HD 189733b primarily resides within the Alfvén surface, making this system likely to host star-planet magnetic interactions. This suggests that HD 189733b could host a magnetic field capable of driving these interactions. The two models are driven using a Zeeman Doppler-Imaging magnetic map from 2023 spectro-polarimetric observations, showing that incorporating Alfvén wave heating is crucial for accurately reproducing star-planet magnetic interactions. Modelling such physical processes is thus a promising approach for characterising exoplanetary magnetic fields, and could significantly help us understanding magnetic coupling in exoplanetary atmospheres.
How to cite: Gourvès, C. and Strugarek, A.: The role of magnetic coupling in exoplanet atmospheres: insights from star-planet magnetic interactions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2525, https://doi.org/10.5194/egusphere-egu25-2525, 2025.
Magnetic fields are expected to influence the atmospheric dynamics of hot and ultra-hot Jupiters; however, due to the disparate conditions between the day and night sides, modelling their impact can be difficult. To make the problem tractable, interactions with the magnetic field are often reduced to the inclusion of a magnetic drag term. In this talk, I will demonstrate the impact of vertical and meridional drag from a background dipole magnetic field on the flows in hot Jupiter atmospheres and show that the inclusion of meridional and vertical drag can limit flows over the poles and create a relatively static dayside hot spot around the substellar point, something not seen in models that only consider zonal drag.
How to cite: Christie, D.: Geometric Considerations in Hot Jupiter Magnetic Drag Models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20060, https://doi.org/10.5194/egusphere-egu25-20060, 2025.
With the development of ever-improving telescopes capable of observing exoplanet atmospheres, there is a growing demand for enhanced 3D climate models to support and help interpret observational data. However, the computationally intensive and time-consuming nature of General Circulation Models (GCMs) poses significant challenges for simulating a wide range of exoplanetary atmospheres. These challenges are further amplified by the need to rerun every simulation when altering the inner workings of the GCM, such as updating physical assumptions, which makes exploring new physical scenarios difficult.
Grid studies have been employed to explore parameter spaces, but this approach introduces additional complexity with each varying parameter. To address these limitations, a machine learning approach was applied to interpolate a grid of GCM simulations, done with the ExoRad package, representing hot Jupiters orbiting different host stars at varying distances. The performance of our machine learning frameworks in capturing 3D temperature and wind structures to bridge gaps in the model grid will be discussed. Furthermore, it will be explored how these predictions are reflected in simulated transmission spectra that compare to observational properties of space missions like CHEOPS, JWST and PLATO. This work is part of our science support efforts within the PLATO WPs 116700 and 116800.
How to cite: Plaschzug, A., Reza, A., Carone, L., and Helling, C.: Interpolating a Grid of GCM-Simulated Tidally Locked Gaseous Exoplanets Using Machine Learning, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4212, https://doi.org/10.5194/egusphere-egu25-4212, 2025.
With the new generation of space missions like JWST, CHEOPS and PLATO, the characterisation of gas giant planets like WASP-17 b, WASP-107 b, WASP-39 b, HD189733 b and WASP-43 b has become possible. The 3D General Circulation Model ExoRad is used to simulate 3D atmosphere structures for exoplanets orbiting M-, K-, G-, F- and A-type stars. 1D profiles are extracted across different locations as input for our kinetic, non-equilibrium cloud model to gain insight on the chemistry and dynamic behaviour of their atmospheres. The Jupiter-sized planets are tidally locked and a wide range of global temperatures (TGlobal = 400K-2600K), resulting in a grid of a total of 60 different simulated planets. This grid serves as input interpretation for JWST, CHEOPS and PLATO data.
Through this hierarchical modelling approach, a deeper understanding of the host star’s influence on the thermodynamic structure of these planets and its effect on the clouds is obtained. Models of formation through nucleation, surface growth, evaporation, and gravitational settling, consistent with element conservation, are used to calculate the nucleation rate, the local average particle size and the cloud particle composition.
A systematic comparison of atmosphere and cloud structures is possible based on our exoplanet model grid. Here, an in-depth examination of the iron composition of the cloud particle was conducted, focusing on where it is found in the atmosphere across different pressure regimes. This work is part of our science support efforts within the PLATO WPs 116700 and 116800.
How to cite: Gernjak, S., Carone, L., and Helling, C.: Where is the iron in cloudy atmospheres of Jupiter-sized exoplanets?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4342, https://doi.org/10.5194/egusphere-egu25-4342, 2025.
Clouds on exoplanets are hypothesized to explain the absence of expected molecular or atomic absorption features in optical and near-infrared spectra. These observations are obtained using space-based telescopes such as CHEOPS, JWST, and the future PLATO mission, as well as ground-based telescopes like the VLT. These clouds form through the condensation of thermally stable materials onto cloud condensation nuclei (CCN) via gas-surface reactions, playing a crucial role in shaping the observed atmospheric properties. In rocky exoplanets, CCN are supplied by processes such as sandstorms, combustion, and volcanic eruptions. However, gaseous exoplanets lack direct sources of CCN. Instead, CCN form through a bottom-up nucleation process, where small molecules like TiO2 undergo a series of chemical reactions to form larger molecular clusters [(TiO2)N], which grow until they reach a size sufficient to undergo a phase transition from gas to solid, ultimately forming CCN. Previous studies have explored nucleation using various theories, including Classical Nucleation Theory, Modified Classical Nucleation Theory, Non-Classical Nucleation theory, and Kinetic Nucleation Networks. All these approaches require thermochemical data for the nucleating species. While experimental studies have provided insights, limitations in replicating substellar atmospheric conditions, such as extreme temperatures and pressures, hinder their applicability. Quantum mechanical methods have been employed to address these challenges by optimizing cluster geometries and calculating thermochemical properties. However, these computationally expensive methods can take weeks to months for big clusters.
This project utilizes machine learning (ML) models to predict the geometric and thermochemical properties of large molecular clusters. The initial objective involves developing a comprehensive data catalog by integrating in-house molecular data with information from the literature. The dataset is utilized to train the ML models, which are then employed to predict the structural and thermochemical properties of larger molecular clusters. The ultimate goal is to identify clusters capable of undergoing phase transitions from the gas phase to the solid phase, serving as cloud condensation nuclei (CCN) essential for cloud formation in gaseous exoplanets. This work aligns with the scientific objectives of PLATO Work Packages 116700 and 116800. Additionally, it complements the goals of JWST Proposal 6045 (Cycle 3), titled “Detecting Ongoing Gas-to-Solid Nucleation on the Ultra-Hot Planet WASP-76 b”, which aims to observe a single transit of WASP-76 b using MIRI/LRS.
How to cite: Bisht, D., Helling, C., Reza, A., Molinos, H. L., and Aichhorn, M.: Machine Learning-Driven Insights into Cloud CondensationNuclei Formation in Gaseous Exoplanet Atmospheres, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7002, https://doi.org/10.5194/egusphere-egu25-7002, 2025.
This study investigates the effect of varying internal heat flux and atmospheric drag on the observable properties of WASP-76b, showing GCM outputs and comparisons with JWST phase-curve observations. A suite of general circulation models are run, which solve the primitive equations of meteorology coupled to non-grey correlated-k radiative transfer with the SPARC/MITgcm. The effect of Lorentz forces are represented by changing a spatially constant drag timescale, and internal temperature is varied across a range of predicted values for hot and ultra-hot Jupiters. The results are then post-processed using the gCMRT radiative transfer code to produce simulated phase curves for comparison with brand new JWST/NIRSpec data, following the observation of this target on January 5th 2025. This study will build on the work of May & Komacek et al. 2021 by incorporating non-grey radiative transfer through the SPARC scheme and using the JWST/NIRSpec phase curve data alongside the Spitzer phase curve as well as ground-based high-resolution spectroscopy, helping to deepen our understanding of the effect of internal heat fluxes and atmospheric drag forces on the observable properties of ultra-hot Jupiters.
How to cite: Allen, J., Komacek, T., and Wardenier, J.: Circulation models and JWST observations of the inflated ultra-hot Jupiter WASP-76b, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20501, https://doi.org/10.5194/egusphere-egu25-20501, 2025.
A major challenge for exoplanet science is to understand the connection between the atmosphere and the interior of exoplanets in order to understand their origins, structure and evolution [Fortney et al. ]. The observed chemical composition can be affected by the conditions in the deep atmosphere (intrinsic temperature, vertical mixing, interaction with a magma ocean,…), while measuring the atmospheric composition can help to break some degeneracies in the interior of exoplanets. Atmosphere-interior retrievals combining spectroscopic data with mass and radius measurements have been successfully applied to JWST observations of the warm Neptune WASP-107 b [Sing et al. 2024, Welbanks et al. 2024]. They revealed a high internal heat flux and large core, with some differences between the two studies (Mcore=11.5+/-3 MEarth for Sing et al. 2024 and Mcore >22 MEarth for Welbanks et al. 2024).
Here we use the coupled atmosphere-interior model called HADES [Wilkinson et al. 2024] to derive planetary properties (core mass, metallicity and intrinsic temperature) of giant exoplanets. First, we compare our results for WASP-107 b with previous measurements. Then we apply our model to a sample of giant exoplanets to derive trends with planetary mass and irradiation.
References
Fortney et al., JGR Planets, 2021
Sing et al., Nature, 2024
Welbanks et al., Nature, 2024
Wilkinson et al., A&A, 2024
How to cite: Perrier, B., Charnay, B., and Wilkinson, C.: Characterization of the interior of giant exoplanets with JWST transit observations and a coupled atmosphere-interior model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13126, https://doi.org/10.5194/egusphere-egu25-13126, 2025.
Hycean planets are exoplanets characterized by water oceans and hydrogen-rich atmospheres. These planets are high-priority targets for biosignature searches, thanks to their abundant surface liquid water combined with having easy-to-characterize hydrogen-rich atmospheres. The climates and potential habitability of hycean planets are still poorly understood, however. One of their most unusual climate features is moist convection inhibition. In a hydrogen-rich atmosphere the presence of H2O can suppress moist convection and dramatically alter a planet’s temperature structure, an effect which so far has largely been studied for gas giants in the Solar System. This work develops pen-and-paper theory to analyze the effects of moist convective inhibition on hycean planets. The theory is tested and verified against a one-dimensional radiative-convective model. We show that hycean planets with moderately thick atmospheres can exhibit climate bistability. The bistability arises because when the inhibition occurs, the cooling in the upper atmosphere can offset the radiative effect of surface warming, which is most effective when the total optical thickness is slightly greater than unity. In addition, our results show that climates of hycean planets are highly sensitive to small-scale vertical diffusion in the inhibition layer. This diffusion is determined by a wide range of processes which are difficult to resolve in 1D models, such as convective overshoot and large-scale horizontal shear. Our results suggest that hycean planets have unexpectedly rich climate dynamics, and highlight the importance of sophisticated 3D modeling for understanding the potential habitability of hycean worlds
How to cite: Gao, Y., Koll, D., and Ding, F.: Possible climate bistability on hycean planets, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4899, https://doi.org/10.5194/egusphere-egu25-4899, 2025.
The study of exoplanets has advanced significantly since the discovery of the first exoplanet orbiting a Sun-like star in 1995, with over 5,800 exoplanets identified to date. This research focuses on TRAPPIST-1e, one of seven rocky planets in the TRAPPIST-1 system discovered using the transit method. TRAPPIST-1e is of particular interest due to its position within the habitable zone, where liquid water could exist, and its Earth-like characteristics, such as similar mass, radius, and surface gravity.
The tidally locked nature of TRAPPIST-1e presents unique atmospheric and climatic dynamics, significantly different from Earth's, making it an excellent candidate for theoretical and observational studies. This research employs the NASA developped ROCKE-3D Global Circulation Model to simulate various atmospheric scenarios, ranging from Venus-like conditions to aquaplanets with varying ocean depths and nitrogen-carbon dioxide compositions. Synthetic transmission spectra and climate data are generated to explore these scenarios, providing insights into potential habitability and atmospheric behavior.
Given the current limitations in observational technology, simulations play a vital role in understanding TRAPPIST-1e’s atmosphere. Using specifications from instruments such as ELT ANDES, VLT CRIRES+, and JWST MIRI, the project evaluates the spectral resolution required to extract meaningful atmospheric features. These findings aim to bridge gaps in exoplanetary atmospheric studies and prepare for future missions, contributing to our understanding of the diversity of worlds beyond our Solar System.
How to cite: Krilanovic, M.: From Surface to Spectra: Characterizing TRAPPIST-1e’s Atmosphere and Climate, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19977, https://doi.org/10.5194/egusphere-egu25-19977, 2025.
The Large Interferometer For Exoplanets (LIFE) is a proposed space mission that enables the spectral characterization of the thermal emission of exoplanets in the solar neighborhood. The mission is designed to search for global atmospheric biosignatures on dozens of temperate terrestrial exoplanets and it will investigate the diversity of other worlds, following in the footsteps of the current and next-generation exoplanet space missions, JWST, TESS, CHEOPS, Ariel, and PLATO. Here, we will present an update on the latest concept and science case developments of the LIFE collaboration, focusing on the recent publications Alei et al. (2024) and Cesario et al. (2024). Combined observations in the UV/VIS/NIR+MIR observations with HWO + LIFE would provide synergistic constraints on temperate terrestrial exoplanets, including the atmospheric thermal profile to ~10 K uncertainty, and decisively constrain atmospheric abundances of CO2, H2O, O2, and O3, and weakly constrain CO and CH4 (Alei et al. 2024). Exploration of young planetary systems in nearby young stellar associations with the LIFE mission will enable the rapid (~min to hr) detection of terrestrial protoplanets in their magma ocean phase, both for M and G dwarfs, which would enable constraints on the transition from primary to secondary atmospheres (Cesario et al. 2024). Characterization of the atmospheres of terrestrial exoplanets in time enables constraints on prebiotic chemical environments and the near-surface habitability of young and mature terrestrial exoplanets.
References:
Alei, E. et al. (2024). Large Interferometer For Exoplanets (LIFE): XIII. The Value of Combining Thermal Emission and Reflected Light for the Characterization of Earth Twins. Astronomy & Astrophysics 689, A245.
Cesario, L. et al. (2024) Large Interferometer For Exoplanets (LIFE)-XIV. Finding terrestrial protoplanets in the galactic neighborhood. Astronomy & Astrophysics 692, A172.
How to cite: Lichtenberg, T., Alei, E., Cesario, L., Quanz, S., Glauser, A., Angerhausen, D., Rugheimer, S., Kammerer, J., Fortier, A., Ireland, M., Defrere, D., Linz, H., Noack, L., Braam, M., and Collaboration, L.: The Large Interferometer For Exoplanets (LIFE): synergy with HWO & protoplanet detection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4223, https://doi.org/10.5194/egusphere-egu25-4223, 2025.
