How to cite: Sergeev, D.: Shall I compare thee to a distant world? The importance of inter-planet and inter-model comparative studies., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22029, https://doi.org/10.5194/egusphere-egu24-22029, 2024.

Convective instabilities in the lowermost part of the atmosphere, so called the planetary boundary layer, can lead to the formation of convective vortices and form dust devils both on Earth and Mars. We performed mesoscale simulations for a Mars-analog terrestrial site, Makgadikgadi Pan - Botswana [1,2], where a state-of-the art field campaign was conducted to investigate the terrestrial dust devils, and the InSight landing site [3] using WRF/MarsWRF models [4,5]. We then combined our atmospheric modeling with in-situ observations of wind and pressure to perform a comparative boundary-layer meteorology study. We focused on the length and time of scales of turbulence and investigated the turbulent spectrum.

[1] Toledo, D., Apéstigue, V., Arruego, I., Montoro, F., Martinez-Oter, J., Serrano, F., Yela, M., Carrasco-Blázquez, I. and Franchi, F., 2022, September. Investigating dust devils on Mars through the Makadikadi Salt Pans analogue (Botswana). In European Planetary Science Congress (pp. EPSC2022-485).
[2] Toledo, D., Apéstigue, V., Martinez-Oter, J., Franchi, F., Serrano, F., Yela, M., De La Torre Juarez, M., Rodriguez-Manfredi, J.A. and Arruego, I., 2023. Using the Perseverance MEDA-RDS to identify and track dust devils and dust-lifting gust fronts. Frontiers in Astronomy and Space Sciences, 10, p.1221726.
[3] Lorenz, R.D., Spiga, A., Lognonné, P., Plasman, M., Newman, C.E. and Charalambous, C., 2021. The whirlwinds of Elysium: A catalog and meteorological characteristics of “dust devil” vortices observed by InSight on Mars. Icarus, 355, p.114119.
[4] Temel, O., Senel, C.B., Porchetta, S., Muñoz-Esparza, D., Mischna, M.A., Van Hoolst, T., van Beeck, J. and Karatekin, Ö., 2021. Large eddy simulations of the Martian convective boundary layer: towards developing a new planetary boundary layer scheme. Atmospheric Research, 250, p.105381.
[5] Temel, O., Bricteux, L. and van Beeck, J., 2018. Coupled WRF-OpenFOAM study of wind flow over complex terrain. Journal of Wind Engineering and Industrial Aerodynamics, 174, pp.152-169.

How to cite: Temel, O., Karatekin, O., Apéstigue Palacio, V., Daniel, T., Arruego, I., Franchi, F., Martinez, G., and Senel, C. B.: Turbulence statistics of terrestrial Mars-analog and Martian dust devils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11239, https://doi.org/10.5194/egusphere-egu24-11239, 2024.

Convective vortices, and their particle-laden counterparts dust devils, are an important feature of the meteorology of both Mars and terrestrial desert areas. In addition to being interesting phenomena in their own right, they can cause occasional damage and even death.  

The last 12 years has seen the generation of statistically-robust catalogs of vortex encounters from long-lived (>1000 Sol) landers and rovers equipped with meteorological instrumentation, namely MSL, InSight and Mars 2020. 

 Although previous landers (Phoenix and Pathfinder, lasting ~100 Sols) yielded catalogs that were enough to indicate useful analytic function descriptions of vortex population functions (e.g. power laws or exponentials of number versus measured pressure drop), the new generation of missions provide much more robust statistics, and also have had more extensive instrumentation, permitting the documentation of wind speed, dust loading and even seismic characteristics of vortex encounters.

In the 2000s, the Mars statistics were in fact rather better than those available for the Earth, but the advent of inexpensive and low-power data logging systems with flash memory permitted the long-duration (months) acquisition of high-cadence (>1/second) pressure and other data required to detect small vortices in unattended field measurement campaigns. Inexpensive timelapse cameras have also permitted optical surveys of dust devils that are comparable with those from Mars landed and orbital missions.

In many respects the populations of vortex events are surprisingly similar on the two worlds, when expressed as a normalized peak pressure drop (pressure drop divided by ambient pressure : this quantity is proportional to the peak wind speed at the wall of the vortex).  The cumulative rate of encounters typically varies as a power law with an exponent of about -2, and Martian rates are a factor of several higher than those on Earth.  Although the convective heating rates of the respective surfaces are somewhat different, a key difference is that the Martian Planetary Boundary Layer, which sets the upper limit on vortex size, is much deeper, and Martian dust devils are typically larger than Earth’s as a result.  

I will review these population functions and their implications for meteorology, dust lifting and safety.

How to cite: Lorenz, R.: Comparing the Dust Devil Vortex Populations on Mars and Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4489, https://doi.org/10.5194/egusphere-egu24-4489, 2024.

The search for Earth-like planets is a subject of great importance in the world of planetology today. Detecting such planets is challenging and requires a great deal of observation time. With future missions such as PLATO or LIFE, one of the main objectives of which is to detect small, moderate-temperature planets like the Earth, it is important to understand in what types of systems these plants form and around which stars we can expect to detect them. We present here a theoretical statistical study of the most favorable conditions for a planetary system to host an ELP (Earth-like planet). Based on three populations of synthetic planetary systems generated using the Bern model around three different types of stars, this study aims to create a profile of a typical system that harbors an ELP. By using an observational bias, we generate new populations that can be compared to observed systems. We initially examine the distribution of ELPs across different categories of theoretical and observed architectures. The changes in architecture resulting from the application of a bias are also investigated, highlighting the relationship between "theoretical" and "biased" architectures. A more detailed analysis is then conducted, linking the “biased” architecture of a system with the physical properties of its innermost observable planet, in order to establish the most favorable conditions for the presence or absence of an ELP in a system. Several quantities, such as the mass, radius, period and water fraction of this planet, emerge as correlated with the presence or the absence of an ELP.

How to cite: Davoult, J. and Alibert, Y.: Earth-like planets hosting systems: architectures and properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2151, https://doi.org/10.5194/egusphere-egu24-2151, 2024.

The Curiosity rover has moved more than 31 km from the landing site at the very bottom of the crater and has climbed more than ∼750 m into the Mnt. Sharp foothills over more than five Martian years. A significant change in temperatures and pressures measured by the REMS monitoring weather station aboard the Curiosity rover has been detected during that traverse.
On Earth deep valleys, like the ones in Alps, and craters on Mars like Gale accumulate masses of cold air at night, a.k.a. cold pools, at the bottom of the craters. These pockets of cold air change aspects of local micrometeorology at the bottom of a deep valley compared to the slopes. Downslope winds originating from both Mnt. Sharp and crater rims converge at the very bottom of the crater floor and may produce a vortex in the very stable and shallow nocturnal air mass [Rafkin et al. 2016]. This flow would prevent the nighttime accumulation of any tracer along the slopes above the cold pool and facilitate the convergence and accumulation of tracers in the bottom of the crater. The exception is during the northern hemisphere winter (around Ls 270 when strong northerly winds tend to scour the crater air mass day and night [Pla-García et al. in 2019].
As Curiosity ascends, we can examine whether these cold air masses exist at the very bottom of the crater and whether the rover moves away from them when reaching a specific height through Mnt. Sharp slopes. One indication is an increase in nighttime temperatures as the rover climbs Mt. Sharp’s slope. Those interannual increments of nighttime temperatures at Gale show a smooth variation within the lower layers before changing scenarios from landing location and tosol’s (Figure). To distinguish this effect from seasonal trends, an analysis of potential temperatures was performed (Figure). Comparing minimum to average temperatures in Figure allows to relate the changes to seasonal or other effects. The figure shows the annual evolution of the Martian air temperature using a Fourier adjustment. Modeling and observations strongly suggest that the rover has ascended to elevations above the cold pool at the bottom of the crater [Ruíz-Pérez et al. 2024 in preparation].

How to cite: Ruíz-Pérez, M., Pla-Garcia, J., de la Torre-Juarez, M., and Rafkin, S.: Cold pool pockets develop at the bottom of Gale crater (Mars), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15714, https://doi.org/10.5194/egusphere-egu24-15714, 2024.

We investigate the feasibility of measuring methane on Mars using a satellite based lidar at 3.3 um which has the advantage over passive instruments in being able to measure methane at night. Line selection, power requirements, signal to noise, and other details are discussed. Comparisons with other technologies are made. Previous measurements are discussed and the possible advantages of measurements that Lidar can obtain are presented. Subterranean life and other processes are investigated as a possible origin of methane on Mars. Comparisons of similar subterranean life on earth are used as a model for possible subterranean life on Mars and elsewhere.

How to cite: Campbell, J., Liu, Z., Lin, B., Yu, J., and Geng, J.: On the feasibility of measuring methane on Mars using 3.3 um lidar from space, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20933, https://doi.org/10.5194/egusphere-egu24-20933, 2024.

The exoplanet community possesses an incredible variety of models to match the astronomical diversity of exoplanets. Those models are used to either predict or interpret exoplanet data. However, contrary to Earth science, we have no existing ground truth to validate those models. Meanwhile, we would still learn a lot from benchmarking exoplanet models together to increase the robustness in our data prediction and interpretation, to identify bugs and to highlight model features that would require additional developments.

The Climates Using Interactive Suites of Intercomparisons Nested for Exoplanet Studies (CUISINES) Working Group of NASA’s Nexus for Exoplanet Systems Science (NExSS) supports a systematized approach to evaluating the performance of exoplanet models, and provides here a framework for conducting community-organized exoplanet Model Intercomparison Projects (exoMIPs). The CUISINES framework adapts Earth climate community practices specifically for the needs of the exoplanet researchers, encompassing a range of model types, planetary targets, and parameter space studies. 

In this presentation, we will give updates on the various exoMIPs and we will provide insights on our findings to make an exoplanet model intercomparison a success on short and long timescales.

How to cite: Fauchez, T., Sohl, L., Chaverot, G., Christie, D., Deitrick, R., Haqq-Misra, J., Harman, S., Iro, N., Tsigaridis, K., and Villanueva, G.: The CUISINES 2024 menu: Updates and progress on a large exoplanet model intercomparison framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6826, https://doi.org/10.5194/egusphere-egu24-6826, 2024.

With ongoing missions such as the James Webb Space Telescope and planned initiatives such as the Large Interferometer For Exoplanets (LIFE), the detection and attribution of biosignatures in exoplanetary atmospheres increasingly becomes a point of focus. However, in order to assess how different biosignatures manifest themselves in the atmospheres of rocky exoplanets in contrast to our temperate Earth, improved insights into the maintenance of earthlike atmospheric biosignatures in different atmospheres are necessary. 

Here, we identify and investigate the main processes and possible couplings between atmospheric climate and photochemistry for earthlike planets across the inner habitable zone. We also study the detectability of the modelled spectral features with the LIFE simulator to assess how the atmospheres of planets with an earthlike biosphere may appear to future missions like the LIFE interferometer. 

We use the global-mean, stationary, coupled climate-chemistry column model, 1D-TERRA, to simulate the climate and chemistry of planetary atmospheres at different distances from the Sun, initially assuming Earth's planetary parameters and evolution. We run six scenarios: we assume rocky exoplanets with Earth’s biomass fluxes forming around the Sun with insolation from 100% to 150% in steps of 10%. From the resulting output of temperature and composition profiles, we calculate theoretical transmission and emission spectra using a radiative transfer model (GARLIC).

The models show moderate ocean evaporation as the planet moves closer to the Sun, which results in water-vapour-rich atmospheres with the partial pressures of steam ranging from about 0.01 bar (modern Earth insolation, S=1) up to 0.6 bar (S=1.5). In the latter model,  the global mean surface temperature increases to 365.4K. This is mainly due to the higher energy input and the enhanced greenhouse effect due to increased amounts of water vapour in the atmosphere. Regarding key atmospheric biosignatures, ozone, surprisingly, mostly survives in the middle atmosphere in all scenarios, mainly because hydrogen oxide abundances, a catalytic sink for ozone, are prevented from strongly increasing due to reactions with nitrogen oxides. Methane is strongly removed for insolations above 20% those of Earth, because rising water abundances strongly increase hydroxyl (OH) (via UV photolysis) the main sink for methane. Nitrous oxide (N2O) generally survives, mainly due to trade-off effects where enhanced photolytic loss on upper layers due to higher insolation is counterbalanced by stronger absorption of photons on the lower layers due to enhanced water from evaporation. Hydrogen escape rates are 0.690 Tg/yr for the highest insolation scenario. Abiotic oxygen production associated with atmospheric escape of atomic hydrogen as well as catalytic in-situ recycling of oxygen atoms present in HOx species, lead to an increase in the O2 vmr to 0.35 mol/mol on increasing solar insolation from S = 1.0-1.3. For all scenarios, the simulated transmission and emission spectra show clearly evident H2O and CH4 features in the near to mid IR, strong CO2 absorption around 15 microns, and O3 absorption at around 9.6 microns.

How to cite: Taysum, B., van Zelst, I., Grenfell, J. L., Schreier, F., Cabrera, J., and Rauer, H.: Maintenance of atmospheric biosignatures across the inner habitable zone for earthlike planets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17748, https://doi.org/10.5194/egusphere-egu24-17748, 2024.

Many factors influence the long-term evolution of the atmosphere of a rocky planet, including star-planet interactions and late accretion of volatiles. However, for planets where gravity is low enough for a primordial atmosphere to escape (i.e. roughly Earth-size and smaller), the main factor driving the atmospheric evolution will be volcanic outgassing from the interior. 

While for planets in the habitable zone, where liquid water may exist that could allow for an Earth-like carbon-silicate cycle, planets closer to their host star have been suggested to have Venus-like, thick CO2-dominated atmospheres. Our study focusses on the question, how basic planetary parameters such as size, core mass fraction, and surface regime (either stagnant-lid or mobile, such as plate tectonics) may impact the atmosphere, specifically the range of atmospheric pressures as well as their composition, for warm planets where condensation of water as well as an efficient carbon cycle can be excluded. 

We show, that planets with a stagnant lid tend to be hotter in their interior due to the isolating behaviour of the lithosphere, but at the same time tend to have much reduced outgassing efficiencies. At the same time, since volcanic outgassing at the surface of a planet is directly influenced by partial pressures in the atmosphere, compositional variations appear between stagnant-lid or mobile-lid planets, as well as between low-mass and high-mass rocky planets.

Observations with JWST looking at warmer planets (i.e. inside the inner boundary of the habitable zone) might therefore give first-order indications on the outgassing efficiency (coupled with the erosion efficiency of the atmosphere) and surface regime of these rocky planets.

How to cite: Noack, L. and Brachmann, C.: Connecting the interior to the atmosphere: should atmospheres of warm rocky planets differ for stagnant-lid and mobile surface regimes?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9761, https://doi.org/10.5194/egusphere-egu24-9761, 2024.

How to cite: Spaargaren, R., Ballmer, M., Mojzsis, S., and Tackley, P.: Connecting exoplanet mantle mineralogy to surface dynamic regime, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17474, https://doi.org/10.5194/egusphere-egu24-17474, 2024.

Planets are assembled from the same material as their parent stars. Therefore, stellar chemical abundance measurements provide important constraints on the formation, composition, and interior structure of exoplanets. M dwarfs are the most prolific hosts of low-mass, rocky, potentially habitable exoplanets. However, owing to the complexity of their atmospheres (which are marred by molecular absorption), elemental abundances of M dwarfs are notoriously difficult to measure. For key rock-forming elements, state-of-the-art abundance precisions attainable from high-resolution spectroscopy of M dwarfs can be up to an order of magnitude poorer than that for sun-like stars. This would mean a comprehensive characterisation of planets around M dwarfs may be more elusive. We explore examples of consequences for uncertainties in exoplanet modelling, such as condensation sequences, bulk compositions, and core-mantle fractions. We discuss what is required from the stellar science community to make progress.  

How to cite: Shan, Y., Hatalova, P., Tabernero, H., Timmermann, A., Mamonova, E., and Werner, S.: Current limitations in chemical abundance measurements for M dwarfs and implications for exoplanet characterisation  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19230, https://doi.org/10.5194/egusphere-egu24-19230, 2024.

Hydrogen- and helium-rich primordial atmospheres of small rocky planets, formed as a result of planetary accretion, are subject to subsequent modifications of geochemical outgassing. Two outcomes are possible: a secondary atmosphere forms if the outgassing completely replaces the primordial atmosphere, or a hybrid atmosphere results if the primordial atmosphere undergoes a partial loss with its leftover reacting with the newly outgassed species. We constructed a zero-dimensional thermodynamic model where both scenarios can be consistently simulated. The model assumes chemical equilibrium and admits input parameters of oxidation and sulfidation states of the mantle, melt temperature, atmospheric nitrogen content, surface pressure (for secondary atmosphere models), and hydrogen partial pressure (for hybrid atmosphere models). It computes the chemical compositions of outgassing, namely, the volume mixing ratios of various gaseous species. Non-ideal gas behaviors are accounted for in the model and the calculated secondary and hybrid atmospheres both exhibit a vast chemical diversity. For example, hydrogen-rich atmospheres, conventionally deemed of primordial origin, can also stem from interior outgassing. By Monte Carlo sampling in the possible ranges of the input parameters, we found that outgassed methane-dominated atmospheres, regardless of secondary or hybrid, require rather specific conditions: (1) a reduced rocky mantle; (2) relatively low melt temperatures in comparison to those of basaltic or peridotitic melts; (3) relatively high atmosphere pressures (> c.a. 10 bar) on the rocky surface. Moreover, we found that the abundance ratio of CO₂ and CO can serve as a powerful diagnostic of oxygen fugacity of rocky mantles, which could potentially be constrained by future James Webb Space Telescope spectra. The current model does not consider atmospheric escape, chemical kinetics or photochemistry, which awaits to be incorporated in future works.

How to cite: Tian, M. and Heng, K.: Thermodynamic modelling of the outgassing chemistry of Super Earths and sub-Neptunes: applications to secondary and hybrid atmospheres, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7320, https://doi.org/10.5194/egusphere-egu24-7320, 2024.

The dawn of high-resolution observations with the James Webb Space Telescope will enable spatially resolved observations of ultrashort-period rocky exoplanets. Some of these planets orbit so closely to their star that they lack an atmosphere [1], which gives direct access to their surfaces and opens a window to infer their geodynamics [2]. The physical parameters of the ultrashort-period sub-Earth GJ 367 b have been observationally constrained to a planetary radius of about 0.72 to 0.75 Earth-radii and a mass between 0.48 and 0.55 Earth-masses, implying a density of 6200 to 8500 kg/m³ [3, 4], which puts this planet in a Mercury-like interior regime with a thin mantle overlying a fractionally large core.

The dayside temperature ranges between 1500 to 1800 K, thus suggesting the presence of a permanent magma ocean or dayside magma pond on the surface, induced by stellar irradiation. The large uncertainty on the age of the stellar system, between 30 Myr [4] and about 8 Gyr [3], however, introduce severe uncertainties related to the compositional and thermal evolution of the planetary mantle. In this study we perform global 2D spherical annulus StagYY simulations [5, 6] of solid-state mantle convection and surface melting with the goal to constrain the geometric and compositional properties of the planet. Constraining the spatial dimensions of thermodynamic properties of partially molten, atmosphere-less planets like GJ 367 b offers unique opportunities to constrain the compositional fractionation during magma ocean epochs and provides avenues to constrain the delivery and loss cycle of atmophile elements on strongly irradiated exoplanets.

References:

[1] L. Kreidberg and 18 co-authors. Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b. Nature, 573:87–90, 2019.

[2] T. G. Meier, D. J. Bower, T. Lichtenberg, P. J. Tackley, and B.-O. Demory. Hemispheric Tectonics on LHS 3844b. Astrophys. J. Lett., 908:L48, 2021.

[3] K.W.F. Lam and 78 co-authors. GJ 367 b: A dense, ultrashort-period sub-earth planet transiting a nearby red dwarf star. Science, 374:1271–1275, 2021.

[4] W. Brandner, P. Calissendorff, N. Frankel, and F. Cantalloube. High-contrast, high-angular resolution view of the GJ367 exoplanet system. Mon. Notices Royal Astron. Soc., 513:661–669, 2022.

[5] J. W. Hernlund and P. J. Tackley. Modeling mantle convection in the spherical annulus. Phys. Earth Planet. Int., 171:48–54, 2008.

[6] P. J. Tackley. Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid. Phys. Earth Planet. Int., 171:7–18, 2008.

How to cite: Golabek, G. J., Lichtenberg, T., Bartels, L. M., Tackley, P. J., Meier, T., and Bower, D.: Magma oceanography of the dense, ultrashort-period sub-Earth GJ 367 b, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5832, https://doi.org/10.5194/egusphere-egu24-5832, 2024.

Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System. Thanks to the recent launch of the James Webb Space Telescope (JWST), possible atmospheric constituents such as carbon dioxide (CO2) are now detectable. Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO2 in its atmosphere. Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 µm. We measure a planet-to-star flux ratio of 421 +/- 94 parts per million (ppm), which corresponds to an inferred dayside brightness temperature of 380 +/- 31 K. This high dayside temperature disfavours a thick, CO2-rich atmosphere on the planet. The data rule out cloud-free O2/CO2 mixtures with surface pressures ranging from 10 bar (with 10 ppm CO2) to 0.1 bar (pure CO2). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6 sigma confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio.

How to cite: Zieba, S., Kreidberg, L., Ducrot, E., Gillon, M., Morley, C., Schaefer, L., Tamburo, P., Koll, D. D. B., Lyu, X., Acuña, L., Agol, E., Iyer, A. R., Hu, R., Lincowski, A. P., Meadows, V. S., Selsis, F., Bolmont, E., Mandell, A. M., and Suissa, G.: No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18489, https://doi.org/10.5194/egusphere-egu24-18489, 2024.

The first JWST/MIRI photometric observations of TRAPPIST-1 b allowed for the detection of the thermal emission of the planet at 15 microns, suggesting that the planet could be a bare rock with a zero albedo and no redistribution of heat. Here we present five new occultations of TRAPPIST-1 b observed with MIRI in an additional photometric band at 12.8 microns.  In this presentation we present the results from a joint fit of the 10 eclipses and derive a planet-to-star flux ratio of 452 +/- 86 ppm and 775 +/-90 ppm at 12.8 microns and 15 microns, respectively. 
We show how we tested a large range of models and found that the data can be well fitted by either an airless planet model with an unweathered (fresh) ultramafic surface, that could be indicative of relatively recent geological processes, or, more surprisingly, by a thick pure CO2 atmosphere with photochemical hazes that create a temperature inversion and results in the CO2 feature being seen in emission. 
Our results highlight the challenges in accurately determining a planet's atmospheric or surface nature solely from broadband filter measurements of its emission, but also point towards two very interesting scenarios that will be further investigated with the forthcoming phase curve of TRAPPIST-1 b+c.

How to cite: Ducrot, E., Lagage, P.-O., and Min, M. and the ExoMIRI Team: Combined analysis of the 12.8 and 15 microns JWST/MIRI eclipse observations of TRAPPIST-1 b, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20183, https://doi.org/10.5194/egusphere-egu24-20183, 2024.

Small rocky planets are now known to be very frequent in temperate orbits around low-mass M-dwarfs. The most pressing question regarding these ubiquitous planets concerns their capacity to maintain significant secondary atmospheres despite the adverse environment (high XUV fluxes, winds) and history (long pre-main-sequence) brought by their small host stars. Here, we present the photometric observation by JWST/MIRI of the combined thermal phase curve of the two inner planets of the TRAPPIST-1 system (Cycle 2 program 3077). These observations aimed to determine if the two planets are bare rocks or not by complementing the Cycle 1 measurements of their daysides' thermal emission at 15 microns (for b and c) and 12.8 microns (for b).

How to cite: Gillon, M. and the JWST Program 3077 team: The double phase curve of TRAPPIST-1b and c at 15 microns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9116, https://doi.org/10.5194/egusphere-egu24-9116, 2024.

JWST is currently at the forefront in the search for exoplanet atmospheres. However, the observation of atmospheres of Earth-like planets pushes the limits of the instruments, often requiring multiple observations to be combined. Their interpretation requires complementary theoretical studies to test plausible atmospheric models. We aim to determine the atmospheric survivability of rocky planets around late M-type dwarfs by modelling the upper atmosphere of the TRAPPIST-1 planets' response to incoming stellar extreme ultraviolet and X-ray (XUV) radiation. This is done using a self-consistent thermo-chemical code to create a grid of models simulating possible atmospheres. Specifically we study the atmospheric mass loss due to Jeans escape induced by XUV radiation. Our models indicate that even Jeans escape is catastrophically large for these N2 or CO2 dominated atmospheres over evolutionary timescales, which has important observational implications.

How to cite: Van Looveren, G., Güdel, M., Boro Saikia, S., and Kislyakova, K.: Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1746, https://doi.org/10.5194/egusphere-egu24-1746, 2024.

Recent JWST observations of rocky planets, such as TRAPPIST-1, and the increasing number of rocky planets discovered orbiting close to their host star, strongly motivates the improvement of tidal modeling.
Beside, recent JWST observations of the thermal emission from TRAPPIST-1 b and c have provided constraints on their atmospheres (Greene et al. 2023; Ih et al. 2023; Zieba et al. 2023; Lincowski et al. 2023). 
In this context, It is crucial to use a coherent tidal model that encapsulates the complex response of rocky planets to stress, to understand the evolution of exoplanets and interpret new data.

Our presentation will focus on recent developments on the implementation of the formalism of Kaula (1964) in the N-body code Posidonius (Blanco-Cuaresma & Bolmont 2017; Bolmont et al. 2020).
This formalism consists in using a decomposition of the tidal potential into Fourier harmonic modes, which allows to account for the frequency dependence of the tidal response of rocky bodies.
It makes it general enough to take into account for any type of internal structure, as well as the presence of ice or surface liquid water.
We will present our results on the rotational state of TRAPPIST-1 planets, revisiting the assumption of the perfect synchronization state resulting from tidal evolution. 
Given that the rotational state influences the heat redistribution regime, precise estimation of their rotational state is critical.
Various internal structures were explored with the Burnman code (Cottaar et al. 2014; Myhill et al. 2021)., considering compositions and core sizes compatible with mass and radius estimations from Agol et al. (2021).

Our simulations showed that planet-planet interactions induce rapid variations in the mean motions of the planets. 
These variations occur too quickly for tides to maintain synchronized rotation states with the mean motion. 
This results in sub-stellar point drifts, causing planets to complete full solar days with periods ranging from 42 to 103 years depending on the planet. 
The competition between mean motion variations and tidal damping, and thus sub-stellar drifts, is contingent on the internal structure of the planet under consideration. 
As a result, remnant rotation is expected to facilitate the redistribution of heat on the planet's surface, modifying habitability conditions by mitigating the cold-trap effect on the night side (Turbet et al. 2016) and redistributing cloud formation on the day side (Turbet et al. 2021).
Additionally, we will present preliminary results on the coupling between the spin and the orbital evolution of planets in compact mean motion resonances (MMRs), in particular with the presence of obliquity spin-orbit resonances (SOR), on time transit variations (TTV) and on the mean motion resonances for the TRAPPIST-1 system and the potential observability of such effects.

How to cite: Revol, A., Bolmont, E., Sastre, M. V., Libert, A.-S., Tobie, G., and Blanco-Cuaresma, S.: Improving tidal interaction for compact N-body planetary system., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17280, https://doi.org/10.5194/egusphere-egu24-17280, 2024.

Ocean modelling is often sidelined by exoclimate modellers, mostly due to the associated computational expense of spinning up dynamic oceans. However, oceanic heat transport can critically impact the climate and observables for M-planets in the middle of their habitable zones (e.g., [1]) like TRAPPIST-1e. The oceanic description can also affect the number of final stable climatic states of the planet ([2]). Short of using a fully dynamic ocean model, a compromise used in most exoplanet General Circulation Models (GCMs) is a slab ocean model without oceanic heat transport.

Here, we will first present our improved compromise - the new dynamical slab ocean model integrated into the Generic-PCM ([3]), previously known as the LMD Generic GCM (e.g., [4]). Our parallelisable ocean model not only accounts for sea-ice/snow evolution, but also features wind-driven ocean transport (Ekman transport), horizontal eddy diffusion and convective adjustment between oceanic layers. When coupled with the atmosphere, it effectively reproduces critical attributes observed on modern Earth, including the major oceanic heat flows, an annually averaged surface temperature of 13 C, planetary albedo of 0.32 and sea ice coverage spanning 18 million sq. km.

Further, we will delve into the implications of a dynamical slab ocean model for TRAPPIST-1e. Despite recent JWST observations indicating the lack of a (thick) atmosphere for TRAPPIST-1b ([5]) and 1c ([6]), the planets farther away from the star, like 1e, may have retained moderately thick atmospheres. Assuming this, and if 1e formed with a substantial water reservoir ([7]), it could have sustained liquid water oceans ([8]). In general, the presence of oceanic heat transport can give rise to distinct oceanic patterns, as illustrated by the “lobster” pattern observed for Proxima Centauri b by [9], in contrast to the “eyeball” pattern in [4], observed in its absence. Moreover, studies suggest that the climates of Proxima Centauri b and TRAPPIST-1e may share similarities ([4], [8]). In this context, we will present findings from our new dynamical slab ocean within the Generic-PCM for TRAPPIST-1e. These results will then be systematically compared with those of [9], which used ROCKE-3D ([10]) with a dynamic ocean model. We believe that this will help in strengthening our understanding of the climate of TRAPPIST-1e and also offer insights into comparative exoplanetary climate research. Finally, we will discuss our findings in the context of habitability, particularly emphasising the role of a dynamical ocean model in informing our understanding of habitable conditions.

References:

[1] Yang et al. (2019b)

[2] Brunetti et al. (2019)

[3] Forget et al. (in prep)

[4] Turbet et al. (2016)

[5] Greene et al. (2023)

[6] Zieba et al. (2023)

[7] Tian & Ida (2015)

[8] Turbet et al. (2018)

[9] Del-Genio et al. (2019)

[10] Way et al. (2017)

How to cite: Bhatnagar, S., Bolmont, E., Brunetti, M., Kasparian, J., Turbet, M., Millour, E., Codron, F., and Revol, A.: Diving into the new dynamical slab ocean of the Generic-PCM: Implications for the climate of TRAPPIST-1e, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18447, https://doi.org/10.5194/egusphere-egu24-18447, 2024.

Recent measurements of the dayside thermal emission of exoplanets TRAPPIST-1b [1] and TRAPPIST-1c [2] were made by the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) F1500W filter which covers the 15-µm carbon dioxide (CO₂) absorption. These photometric secondary-eclipse observations determined the dayside brightness temperature and constrained the magnitude of heat redistribution. For TRAPPIST-1c, which has a Venus-like stellar irradiation, the estimated eclipse depth is 421±94 ppm, corresponding to a dayside brightness temperature of 380±31 K, superior to Venus's equilibrium temperature. Two scenarios stem from the inferred brightness temperature: a moderate heat redistribution or an airless, non-zero bond albedo surface. The observations rendered thick, CO₂-enriched atmospheres unlikely for TRAPPIST-1c, excluding a cloudy (sulphuric acid aerosols) and a clear-sky Venus-like atmosphere at a confidence of 2.6σ and 3.0σ, respectively [2].

New JWST observations (Cycle 2 GO Programme 3077) [3] will obtain thermal emission phase curve measurements for most of TRAPPIST-1c’s orbit (P = 58-hours), identifying the day-night temperature contrast. These will be sensitive to test the case of a moderate heat redistribution [4-8], eventually distinguishing it from spectral features from a rocky surface or those from an airless planet [9]. This research is crucial given that CO₂–dominated atmospheres were predicted as a likely outcome of atmospheric evolution on rocky planets orbiting cooler and less massive stars (M-dwarf stars) than our Sun [10]. Owing to the CO₂ high molecular weight and efficient cooling in the infrared, CO₂-rich atmospheres have extremely cold thermospheres and less expanded upper atmospheres; both can improve resilience to atmospheric escape processes, offering partial protection against M-dwarf lifelong stellar activity [10]. Investigating the status of a possible atmosphere on TRAPPIST-1c is critical to understanding atmospheric evolution on M-dwarf planets.

Here, we use a 3D global circulation model of the atmosphere, the Generic-PCM [8,11-13], to simulate a modern Venus-like atmosphere on TRAPPIST-1c: CO₂-dominated, 92-bar surface pressure with radiatively-active global cover of sulphuric acid aerosols [13]. We also assumed a tidally-locked planet with zero obliquity and eccentricity. We use these simulations to generate high spectral resolution thermal phase curves for three JWST/MIRI filters: F1280W, F1500W and F1800W. We analyse the relationship between phase curve parameters (hot spot offset and amplitude), temperature and large-scale circulation. We find large eastward offsets and small amplitudes compatible with an efficient day-night heat redistribution driven by a superrotating equatorial jet. In addition, we predict a smaller hot spot offset for F1500W due to upper atmosphere CO₂ absorption. These results highlight the possibility of studying at least two different atmospheric levels. The absence of a large hot spot offset on TRAPPIST-1c would rule out a dense, CO₂-rich, absorbing atmosphere on the planet. These results can be expanded to the ever-growing population of rocky exoplanets with Venus-like stellar irradiations to be studied in the following decades [14].

References: [1]Greene+2023.Nature.618; [2]Zieba+2023.Nature.620; [3]Gillon+2023.JWST Proposal 3077; [4]Selsis+2011.A&A.532; [5]Demory+2016.Nature.532; [6]Koll+2016.ApJ.825; [7]Kreidberg+2019.Nature.573; [8]Turbet+2016.A&A.596.A112; [9]Whittaker+2022.AJ.164; [10]Turbet+2020.Space Sci. Rev.216; [11]Forget & Leconte, 2014.Phil.Trans R.Soc.A372; [12]Wordsworth+2011.ApJL.733.L48; [13]Quirino+2023.MNRASL.523.L86; [14]Ostberg+2023.AJ.165.

Funding: This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grant 2023.05220.BD.

How to cite: Quirino, D., Gilli, G., Turbet, M., Fauchez, T., Navarro, T., and Machado, P.: No Venus-like atmosphere on TRAPPIST-1 c: confirmation from 3D climate modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-801, https://doi.org/10.5194/egusphere-egu24-801, 2024.