Abstract

JWST has provided a new wealth of information on exoplanet atmospheres, including one of the most critical components, that being the composition of cloud particles and their 3D global distribution.

In this review talk, I will first outline the basic theories and multiple approaches applied cloud formation in exosolar atmospheres, as well as their general effects on the observed properties of exoplanet atmospheres. Moving through the historical context in brown dwarf atmosphere science to contemporary modelling efforts will serve to provide the audience with a broad literature review and context to the field. A simple interactive python based demonstration will be included to aid understanding of the basic methodology.

Moving into 3D, I will discuss how the field approaches this tricky topic using general circulation models (GCMs) coupled to various flavours of cloud models, from simple diagnostic efforts to complex microphysical models. I will showcase recent progress in the field using these techniques and how they have been used to uncover the complex interactions and feedbacks that clouds can induce in these atmospheres. Another interactive session will elucidate the time-dependent nature of cloud formation in 3D and the modelling of microphysics.

Lastly, I will suggest what types of observational data and programs would best constrain the 3D properties of clouds in exoplanet atmospheres, as well as discuss gaps in theory and data that can be can tackled in future endeavours in the field.

Abstract

Abstract

This study aims to characterize the internal structure of the atmospheres in the benchmark brown dwarfs binary system, WISE J104915.57--531906.1AB. This binary system is the closest and brightest to us and is composed of a primary L7.5 (WISE 1049A) and a secondary T0.5 (WISE 1049B). As both objects are in the L/T transition, we are interested in studying their variability because although both components vary significantly, B presents higher variability than A. We use data from 7h of time-resolved spectroscopy (~57100 spectra for each object) to study their variability, taken by NIRSpec/PRISM BOTS on board JWST (GO 2965).

We select 10 molecular bands in each object's spectrum and calculate their respective light curves. We find the best fit of a sum of sinusoidal functions at the light curves using statistical methods like the f-test. The best fit gives us information about the number of bands present in the atmosphere for that specific depth. Studying the residuals, we found regions of the light curves that could not be accounted for with our sum of sinusoidal functions. We interpret this behavior as spots in the object's atmosphere, which may repeat in the light curve with each successive rotation of the brown dwarf.

From analyzing the contribution functions generated by radiative transfer models, we locate the molecular bands at different pressure depths to generate the first atmospheric map using the JWST data. Thanks to these data, we infer a preliminary vertical structure and have a 3D view of a brown dwarf for the first time.

Spectroscopic phase curves are treasure troves of information, enabling us to make 3D scans of planetary atmospheres and observe the longitudinally dependent distributions of chemical species. This is important, because the atmospheric composition of tidally locked gas giants is determined by locally varying parameters such as the temperature, the wind dynamics, and the incident radiation coming from the host star. As such, the planet shows distinct atmospheric signatures dependent on the phase during which it is observed. Now, with the unprecedented sensitivity of the James Webb Space Telescope, we can finally gain insight in the physical and chemical processes that occur in a planetary atmosphere.

During this presentation, we will present a suite of one-, two-, and three-dimensional photochemical models, exploring in detail the chemistry of the hot Jupiter WASP-43 b. We will match our photochemical results to constraints offered by the mid-infrared phase curve that was obtained using the James Webb Space Telescope (Bell et al. 2024) and derive insights into the metallicity, vertical mixing rate, and wind dynamics of WASP-43 b. Intriguingly, we determine both dynamical and chemical mechanisms that cause a depletion of methane. This presentation will highlight the information content provided to us by phase curves and enable future studies of the chemical distributions of tidally locked exoplanets.

Clouds play a crucial role in shaping the atmospheres of exoplanets, influencing their albedo, heat distribution, and spectrum. While most past studies focused on hot and ultra-hot planets, JWST now allows an in-depth characterisation of warm objects, where the interactions between cloud, circulation, and radiative transfer are yet to be studied in detail.

In this study, we integrate physically motivated, radiatively active, tracer-based clouds in General Circulation Models (GCMs) to analyze the atmosphere of WASP-80b, a warm Jupiter orbiting an M-dwarf star. This planet, with an equilibrium temperature of ~800 K, is analogous to warm sub-Neptunes, making it a crucial target for understanding sub-Neptune atmospheres. We take advantage of the high-quality dataset from JWST obtained through the MANATEE GTO collaboration, allowing us to jointly interpret both high-quality panchromatic emission and absorption spectra ranging from 2.5 to 12 microns with the outputs from a GCM. We provide an in-depth characterisation of the planet's atmospheric dynamics and molecular distribution, including unique photochemical molecules. Realistic insights into the distribution of clouds composed of various species, such as silicates, sulfides, and chlorides, with varying particle sizes were obtained.

While both emission and transmission spectra are very well fitted by cloudless GCMs, the data also appears compatible with small KCl cloud particles, but Na2S condensates can be ruled out due to the strength of their radiative feedback. This showcases the unique insights that can be obtained from global modelling of exoplanet atmospheres.

Our results point towards a homogeneous atmosphere with minimal temperature contrast between the day and night sides, suggesting efficient heat redistribution. Additionally, the presence of photochemical products such as CS2 and the relatively low abundance of CH4 point to active atmospheric chemistry and the possibility of a high internal heat flux. This work not only provides a comprehensive framework for interpreting JWST observations but also enhances the capabilities of GCMs in characterizing the global atmospheres of exoplanets in the JWST era.

Sub-Neptunes with substantial atmospheres are expected to possess magma oceans in contact with the overlying gas. Chemical interactions between the atmosphere and interior could potentially play a critical role in shaping the planet's atmospheric composition and interior structure. Early JWST observations have found a number of highly metal-enriched sub-Neptune atmospheres, which may result either from accretion of heavy elements at formation or from magma-atmosphere interactions. Most previous work examining these interactions has been limited to studying conditions at the atmosphere-mantle boundary, without considering implications for the upper atmosphere, which is probed by spectroscopic observations.

In this talk, we present a modeling architecture to determine observable signatures of magma-atmosphere interactions. We combine an equilibrium chemistry code which models reactions between the core, mantle and atmosphere with a radiative-convective model that determines the composition and structure of the observable upper atmosphere. We examine how different conditions at the atmosphere-mantle boundary as well as different core and mantle compositions impact the resulting upper atmospheric composition.

We compare our findings to recent JWST observations of sub-Neptune atmospheres. In particular, we find that the upper atmosphere of TOI-270 d as measured from its JWST transmission spectrum can be explained as the outcome of interactions between the atmosphere, core and mantle, assuming that the planet originally accreted a solar composition envelope. We discuss the implications of this finding, as well as the further modeling improvements that will be required to fully understand the impact of these processes on atmospheres of the broader sub-Neptune population.

Assessing the prevalence of atmospheres on rocky planets around M-dwarf stars is a top priority of exoplanet science. High-energy activity from M-dwarfs can destroy the atmospheres of these planets, which could in turn explain the lack of atmospheric detections to date. Volcanic outgassing has been proposed as a mechanism to replenish the atmospheres of tidally heated rocky planets. Similarly, L98-59b, a sub-Earth transiting a nearby M dwarf, was recently identified as the most promising exoplanet to detect tidally driven volcanism. We present the transmission spectrum of L98-59b from four transits observed with JWST/NIRSpec. We find a 3.6\( \sigma \) preference for an SO2 atmosphere over the no-atmosphere model based on the Bayesian evidence. The best-fit atmospheric model is in excellent agreement with literature predictions that modeled tidal dissipation on this planet. Such an atmosphere would likely be in a steady state where volcanism balances escape. If so, L98-59b must experience at least eight times as much volcanism and tidal heating per unit mass as Io. If volcanism is driven by runaway melting of the mantle, we predict the existence of a subsurface magma ocean in L98-59b extending up to 60-90% of the planet radius. An SO2-rich volcanic atmosphere on L98-59b would be indicative of an oxidized mantle with an oxygen fugacity of fO2>IW+2.7, and it would imply that L98-59b must have retained some of its volatile endowment despite its proximity to its star. Our findings suggest that volcanism may revive secondary atmospheres on tidally heated rocky planets around M-dwarfs.

One of the key questions in exoplanetary science is determining whether close-in rocky planets can retain atmospheres. A particularly exciting case is that of ultra-short-period, highly irradiated rocky planets, which are predicted to give rise to exotic atmospheres unlike those observed in our Solar System. These planets provide a unique opportunity to explore the predicted compositional diversity resulting from outgassing and surface evaporation. Exposed to intense irradiation that likely strips away their primordial atmospheres, these planets may host secondary atmospheres enriched with species such as Na, O, and SiO.

Here, we present the first near-infrared transmission and emission spectra of the lava world K2-141b, a 1.58 \( \mathcal{R}_\oplus \), 2.31 M⊕, T~2000K hot rocky exoplanet orbiting a K-dwarf star with an ultra-short orbital period of only 7 hours. These precise measurements, obtained using the NIRSpec instrument onboard JWST (PID 2159; PI: Espinoza), allow us to place strong constraints on the atmospheric make-up of this lava world and provide an unprecedented view of these worlds between 3–5 µm. These findings contribute to understanding the evolutionary pathways of ultra-short-period rocky planets (P < 1 day, RP < 2 R⊕), thought to be the stripped cores of mini-Neptunes, and offer valuable insights into planetary formation and survival in highly irradiated environments.

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract

Abstract