Search

In this paper, we explore the detectability of polycyclic aromatic hydrocarbons (PAHs) under diverse planetary conditions, aiming to identify promising targets for future observations of planetary atmospheres. Our primary goal is to determine the minimum detectable mass fractions of PAHs on each studied planet. We integrate the one-dimensional self-consistent model petitcode with petitradtrans , a radiative transfer model, to simulate the transmission spectra of these planets. Subsequently, we employ the pandexo noise simulator using the NIRSpec PRISM instrument aboard the JWST to assess the observability. Then, we conduct a Bayesian analysis through the multinest code. Our findings illustrate that variations in C/O ratios and planet temperatures significantly influence the transmission spectra and the detectability of PAHs. Our results show that planets with [Fe/H] = 0 and 1, C/O = 0.55, and temperatures around 1200 K are the most promising for detecting PAHs, with detectable mass fractions as low as 10 |$^{-7}$|⁠ , or one thousandth of the interstellar medium abundance level. For colder planets with lower metallicities and C/O ratios, as well as hotter planets with carbon-rich atmospheres, PAHs can be detected at abundances around 10 |$^{-6}$|⁠. These results aid our strategy for selecting targets to study PAHs in the atmospheres of exoplanets. [ABSTRACT FROM AUTHOR]

Many known rocky exoplanets are so highly irradiated that their dayside surfaces are molten, and 'silicate atmospheres', composed of rock-forming elements, are generated above these lava pools. The compositions of these 'lava planet' atmospheres are of great interest because they must be linked to the composition of the underlying rocky interiors. It may be possible to investigate these atmospheres, either by detecting them directly via emission spectroscopy or by observing the dust tails which trail the low-mass 'catastrophically evaporating planets'. In this work, we develop a simple chemical model of the lava pool–atmosphere system under mass-loss, to study its evolution. Mass-loss can occur both into space and from the day to the nightside. We show that the system reaches a steady state, where the material in the escaping atmosphere has the same composition as that melted into the lava pool from the mantle. We show that the catastrophically evaporating planets are likely to be in this evolved state. This means that the composition of their dust tails is likely to be a direct trace of the composition of the mantle material that is melted into the lava pool. We further show that, due to the strength of day-to-nightside atmospheric transport, this evolved state may even apply to relatively high-mass planets (⁠|$\gtrsim 1\mathrm \,{M}_{\oplus }$|⁠). Moreover, the low pressure of evolved atmospheres implies that non-detections may not be due to the total lack of an atmosphere. Both conclusions are important for the interpretation of future observations. [ABSTRACT FROM AUTHOR]

Context. Recent advancements in ultra-stable ground-based high-resolution spectrographs have propelled ground-based astronomy to the forefront of exoplanet detection and characterisation. However, the resultant transmission and emission spectra of exoplanetary atmospheres are inevitably contaminated by telluric absorption and emission lines due to the light's transmission through the Earth's atmosphere above the observatory. Retrieving accurate atmospheric parameters depends on accurate modelling and removal of this telluric contamination while preserving the faint underlying exoplanet signal. Aims. There exist many methods to model telluric contamination, whether directly modelling the Earth's transmission spectrum via radiative transfer modelling, or using a principal component analysis (PCA)-like reconstruction to fit the time-invariant features of a spectrum, and removing these models from the observations. We aimed to assess the efficacy of these various telluric removal methods in preserving the underlying exoplanetary spectra. Methods. We compared two of the most common telluric modelling and removal methods, MOLECFIT and the PCA-like algorithm SYSREM, using planetary transmission spectra injected into three high-resolution optical observations taken with ESPRESSO. These planetary signals were injected at orbital periods of P =2 days and P = 12 days, resulting in differing changes in radial velocity during transit. We then retrieved various injected atmospheric model parameters in order to determine the efficacy of the telluric removal methods, as well as their effect on the transmission spectra of exoplanets with varying orbital architectures. Results. For the close-in, high velocity injected signal, we found that SYSREM performed better for species that are also present in the Earth's atmosphere-with accurate and precise retrieval of atmospheric abundances and T-P profiles, across each of the datasets. As we moved to slower moving signals at larger orbital separations, for one of the three datasets, SYSREM dampened the planetary H2O signal, leaving the retrieved abundance value unconstrained. In contrast, the H2O signal was preserved for the telluric modelling method, MOLECFIT. However, this behaviour was not ubiquitous across all three of the injected datasets, with another dataset showing a more precise H2O/Fe ratio when preprocessed with SYSREM. These conflicts highlight the importance of testing individual high-resolution dataset reduction routines independently to ensure real exoplanetary signals are preserved. [ABSTRACT FROM AUTHOR]

We report on the detailed characterization of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 (⁠|$T_\mathrm{eff} = 5662\pm 44$|  K, |$\lt \log R^\prime _{\rm HK}\gt =-4.49$|⁠). The system parameters are derived based on a global fit to K2, TESS and CHEOPS photometry, and HARPS-N and HARPS radial velocities (RVs). A Gaussian process regression analysis is performed simultaneously to the orbital fit of the RVs of K2-370 to effectively model the strong stellar rotation signal with a period of |$13.5\pm 0.05$|  d and measure the planetary RV signal with semi-amplitude |$K_{\rm b}=5.6\pm 0.7$|  m s |$^{-1}$|⁠. We find that K2-370 b has a radius of |$2.67\pm 0.05$|   |${\rm R}_{\rm{\oplus }}$| and a mass of |$11.1\pm 1.4$|   |${\rm M}_{\rm{\oplus }}$|⁠. With an estimated equilibrium temperature |$T_\mathrm{eq}\sim 1480$| K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with |$T_\mathrm{eff}\gt 5500$|  K. The resulting density of |$3.2\pm 0.4$|  g cm |$^{-3}$| implies that K2-370 b either retains a significant (⁠|$\sim 2~{{\ \rm per\ cent}}$| by mass) H-rich atmosphere or its interior contains a high (⁠|$\sim 40~{{\ \rm per\ cent}}$|⁠) water–mass fraction. [ABSTRACT FROM AUTHOR]

The MIRS (MMX InfraRed Spectrometer) infrared spectrometer is part of the scientific payload of JAXA's (Japanese Space Agency) Martian Moon eXploration (MMX) mission. From the reflected sunlight by the planetary surfaces, MIRS will provide information on the Mars atmosphere and the mineralogy and chemistry of its moons. Spectra carried out by the instrument (0.9–3.6 |$\mu$| m) include the thermal emission from the surface, which needs to be modelled and removed to extract the compositional information. In this study, to find an efficient and rapid way to thermally correct infrared data, we developed a simple thermal emission correction based on blackbody fits, and quantify its relative error. To test the method, we generated synthetic spectra of Phobos by using a thermophysical model. We found that the method can produce reflectance spectra with only a few per cent errors, although some undercorrection of the thermal contribution is observed. Compositional information may still be retrieved through the position of absorption bands, despite the thermal emission correction can leave some uncertainties in its strength. We conclude that the method could be used for a first and quick analysis for interpretation of the MIRS data. We also applied our thermal correction methodology to real CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) observations of Phobos. The method looks reliable with a satisfactory removal of the thermal contribution, confirms the presence of an absorption band centred around 2.8 |$\mu$| m, and reveals an apparent absorption at 3.2 |$\mu$| m. However, we are not able to confirm the reality of the 3.2 |$\mu$| m band at this stage, because of the presence of an artefact in CRISM data. [ABSTRACT FROM AUTHOR]

We report the discovery and validation of HD 21520 b, a transiting planet found with Transiting Exoplanet Survey Satellite and orbiting a bright G dwarf (V  = 9.2, |$T_{\rm eff} = 5871 \pm 62$|  K, |$R_{\star } = 1.04\pm 0.02\, {\rm R}_{\odot }$|⁠). HD 21520 b was originally alerted as a system (TOI-4320) consisting of two planet candidates with periods of 703.6 and 46.4 d. However, our analysis supports instead a single-planet system with an orbital period of |$25.1292\pm 0.0001$| d and radius of |$2.70 \pm 0.09\, {\rm R}_{{\oplus }}$|⁠. Three full transits in sectors 4, 30, and 31 match this period and have transit depths and durations in agreement with each other, as does a partial transit in sector 3. We also observe transits using CHEOPS and LCOGT. SOAR and Gemini high-resolution imaging do not indicate the presence of any nearby companions, and Minerva -Australis and CORALIE radial velocities rule out an on-target spectroscopic binary. Additionally, we use ESPRESSO radial velocities to obtain a tentative mass measurement of |$7.9^{+3.2}_{-3.0}\, {\rm M}_{{\oplus }}$|⁠ , with a 3 |$\sigma$| upper limit of 17.7 |${\rm M}_{{\oplus }}$|⁠. Due to the bright nature of its host and likely significant gas envelope of the planet, HD 21520b is a promising candidate for further mass measurements and for atmospheric characterization. [ABSTRACT FROM AUTHOR]

Context. The Neptunian desert and savanna have recently been found to be separated by a ridge, an overdensity of planets in the period range of ≃3–5 days. These features are thought to be shaped by dynamical and atmospheric processes. However, their roles are not yet well understood. Aims. Our aim was to confirm and characterize the super-Neptune TESS candidate TOI-5005.01, which orbits a moderately bright (V = 11.8) solar-type star (G2 V) with an orbital period of 6.3 days. With these properties, TOI-5005.01 is located in the Neptunian savanna near the ridge. Methods. We used Bayesian inference to analyse 38 HARPS radial velocity measurements, three sectors of TESS photometry, and two PEST and TRAPPIST-South transits. We tested a set of models involving eccentric and circular orbits, long-term drifts, and Gaussian processes to account for correlated stellar and instrumental noise. We computed the Bayesian evidence to find the model that best represents our dataset and infer the orbital and physical properties of the system. Results. We confirm TOI-5005 b to be a transiting super-Neptune with a radius of Rp = 6.25 ± 0.24 R⊕ (Rp = 0.558 ± 0.021 RJ) and a mass of Mp = 32.7 ± 5.9 M⊕ (Mp = 0.103 ± 0.018 MJ), which corresponds to a mean density of ρp = 0.74 ± 0.16 g cm−3. Our internal structure modelling indicates that the core mass fraction (CMF = 0.74−0.45+0.05) and envelope metal mass fraction (Zenv = 0.08−0.06+0.41) of TOI-5005 b are degenerate, but the overall metal mass fraction is well constrained to a value slightly lower than that of Neptune and Uranus (Zplanet = 0.76−0.11+0.04). The Zplanet /Zstar ratio is consistent with the well-known mass-metallicity relation, which suggests that TOI-5005 b was formed via core accretion. We also estimated the present-day atmospheric mass-loss rate of TOI-5005 b, but found contrasting predictions depending on the choice of photoevaporation model (0.013 ± 0.008 M⊕ Gyr−1 vs. 0.17 ± 0.12 M⊕ Gyr−1). At a population level, we find statistical evidence (p-value = 0.0092−0.0066+0.0184) that planets in the savanna such as TOI-5005 b tend to show lower densities than planets in the ridge, with a dividing line around 1 g cm−3 , which supports the hypothesis of different evolutionary pathways populating the two regimes. Conclusions. TOI-5005 b is located in a region of the period-radius space that is key to studying the transition between the Neptunian ridge and the savanna. It orbits the brightest star of all such planets known today, which makes it a target of interest for atmospheric and orbital architecture observations that will bring a clearer picture of its overall evolution. [ABSTRACT FROM AUTHOR]

Context. The polar atmosphere of Jupiter is significantly affected by auroral activity, which can induce both thermal and chemical differences compared to the rest of the atmosphere. In particular, auroral activity enhances the production of various hydrocarbons, including benzene. Benzene could be a potential precursor to the formation of the stratospheric hazes. Aims. We investigated the spatial distribution of the benzene abundance across latitudes ranging from 50°S to 81°S and 17°S to 25°S. Additionally, we examined the chemical origin of polar aerosols and their latitudinal distribution. Methods. We employed James Webb Space Telescope (JWST) Mid InfraRed Instrument (MIRI) observations to measure the benzene abundance based on its emission at 674 cm−1. Additionally, we examined the spectral dependence of the aerosol opacity within the 680–760 and 1380–1500 cm−1 spectral ranges, and mapped their distribution from 80°S–50°S. Results. At latitudes lower than 60°S, benzene is found to be up to ten times more abundant compared to lower latitudes. This enhancement of C6H6 is well mixed longitudinally and not particularly concentrated inside the auroral oval. Photochemical models predict a decrease in the abundance as we approach the mid latitudes, but fail at polar latitudes as they do not include ion-neutral chemistry. Moreover, we find that the southern polar atmosphere is enriched with aerosols at ~10 mbar. The optical depth of the aerosols increases at latitudes poleward of ~60°S, similar to the enhancement of C6H6. These aerosols have spectral features similar to the aerosols of Titan and Saturn, and the mass loading is of ~1.2 ± 0.2 × 10−4 g cm−2. Finally, we quantified the impact of these aerosols on the retrieved temperature structure, causing a decrease in the temperature at pressure levels deeper than 10 mbar. Conclusions. We find that the auroral precipitation produces abundant stratospheric aerosols, which must play an important role in the chemistry and dynamics of the planet. [ABSTRACT FROM AUTHOR]

Context. Jovian auroras, the most powerful in the Solar System, result from the interaction between the magnetosphere and atmosphere of Jupiter. While the horizontal morphology of these phenomena has been widely studied, their vertical structure, determined by the penetration depth of the magnetospheric electron into the auroral regions, remains relatively unexplored. Previous observations, including those from the Hubble Space Telescope (HST), have addressed this question to a limited extent. Aims. In this study we aim to map the vertical structure of Jovian auroral emissions. Methods. Using observations from Juno's UltraViolet Spectrograph (UVS), we examined the vertical structure of the auroral emissions. Building on a recent study of auroral energy mapping based on UVS observations that mapped the average energy of precipitating electrons in the Jovian auroral regions, we find a relationship between this average energy and the volume emission rate (VER) of H2 for two types of electron energy distributions: monoenergetic and a kappa distribution with κ = 2.5. Results. Using brightness maps, we derived the 3D VER structure of Jovian auroras in both northern and southern regions, across multiple spacecraft perijoves (PJs). By considering the example of PJ11, we find that the average altitude of the VER peak in the polar emission region is approximately ~250 km for the monoenergetic distribution case and ~190 km for kappa distribution case. In the main emission region, we find that the average altitude of the VER peak is approximately ~260 km for the case of monoenergetic distribution and ~197 km for kappa distribution case. For the other PJs, we obtained results that are very similar to those of PJ11. Conclusions. Our findings are, on average, consistent with measurements from the Galileo probe and the HST observations. This study contributes to a better understanding of the complexity of Jovian auroras and highlights the importance of using Juno observations when probing their vertical structure. Considering the variability in the κ parameter in the auroral region, we also studied the impact of this variability on the vertical structure of the auroral emission. This sensitivity study reveals that the influence of the κ parameter on our results was very weak. However, the impact of the κ variability on the VER amplitude shows that there is an influence on the thermal structure and chemical composition of the atmosphere in the auroral regions. [ABSTRACT FROM AUTHOR]

Context. Atmospheres above lava-ocean planets (LOPs) hold clues related to the properties of their interiors, based on the expectation that the two reservoirs are in chemical equilibrium. Furthermore, such atmospheres are observable with current-generation space- and ground-based telescopes. While efforts have been made to understand how emission spectra are related to the composition of the lava ocean, the influence of oxygen fugacity has yet to be examined in a self-consistent way. Aims. Here, we investigate the sensitivity of atmospheric emission spectra of LOPs to key geochemical parameters, namely, temperature (T), composition (X), and oxygen fugacity (fO2). We also consider the precision involved in recovering these spectra from observations of hot, rocky exoplanets. Methods. We considered 'mineral' atmospheres produced in equilibrium with silicate liquids. We treated fO2 as an independent variable, together with T and X, to compute equilibrium partial pressures (p) of stable gas species at the liquid-gas interface. Above this boundary, the atmospheric speciation and the pressure–temperature structure are computed self-consistently to yield emission spectra. We explored a wide array of plausible compositions, oxygen fugacities (between 6 log10 units below and above the iron-wüstite buffer, IW), and irradiation temperatures (2000, 2500, 3000, and 3500 K) relevant to LOPs. Results. We find that SiO(g), Fe(g) and Mg(g) are the major species below ~IW, ceding to O2(g) and O(g) in more oxidised atmospheres. The transition between the two regimes demarcates a minimum in total pressure (P). Because p scales linearly with X, emission spectra are only modest functions of composition. By contrast, fO2 can vary over orders of magnitude, thereby causing commensurate changes in p. Atmospheres outgassed from reducing melts exhibit intense SiO emission, creating a temperature inversion in the upper atmosphere. Conversely, oxidised atmospheres have lower pSiO and lack thermal inversions, with their resulting emission spectra mimicking that of a black-body. Consequently, the intensity of SiO emission relative to the background, generated by MgO(g), can be used to quantify the fO2 of the atmosphere. Depending on the emission spectroscopy metric of the target, deriving the fO2 of known nearby LOPs is possible with a few secondary occultations observed by JWST. [ABSTRACT FROM AUTHOR]

In protoplanetary discs, small millimetre-centimetre-sized pebbles drift inwards which can aid in planetary growth and influence the chemical composition of their natal discs. Gaps in protoplanetary discs can hinder the effective inward transport of pebbles by trapping the material in pressure bumps. In this work, we explore how multiple planets change the vapour enrichment by gap opening. For this, we extended the chemcomp code to include multiple growing planets and investigated the effect of 1, 2, and 3 planets on the water content and C/O ratio in the gas disc as well as the final composition of the planetary atmosphere. We followed planet migration over evaporation fronts and found that previously trapped pebbles evaporate relatively quickly and enrich the gas. We also found that in a multi-planet system, the atmosphere composition can be reduced in carbon and oxygen compared to the case without other planets, due to the blocking of volatile-rich pebbles by an outer planet. This effect is stronger for lower viscosities because planets migrate further at higher viscosities and eventually cross inner evaporation fronts, releasing previously trapped pebbles. Interestingly, we found that nitrogen remains super-stellar regardless of the number of planets in the system such that super-stellar values in N/H of giant planet atmospheres may be a tracer for the importance of pebble drift and evaporation. [ABSTRACT FROM AUTHOR]

The existence of organic matter presenting a high molecular diversity in extraterrestrial environments is well documented. To understand the origin of this organic diversity, laboratory experiments were developed and showed that irradiation and thermal alteration of simple molecules such as methanol, water, and ammonia in conditions mimicking astrophysical ice environments. Ices containing water, methanol, and ammonia (H2O: MeOH: NH3) photolyzed and monitored by infrared spectroscopy, while the organic matter formed at room temperature was analyzed in situ with infrared spectroscopy and ex situ with high-resolution mass spectrometry. Those ices irradiated at 77 K and 10−8 mbar shows a significant organic molecular diversity: residual organic compounds contain up to 78 C, 188 H, 123 N, and 37 O. Most of them contains all four CHNO atoms (76–86 per cent), followed by CHO (11–17 per cent), and CHN compounds (5–6 per cent). CHNO and CHO compounds are more aliphatic (34–53 per cent), while CHN compounds are mostly condensed aromatics (83–90 per cent). In this work, our objective is to investigate impacts of environment on this organic molecular diversity by focusing on three parameters: photon dose, pressure, and heating rate during the warming process. Analyses of the residue formed showed that the heating rate and pressure weakly alter the abundance of the final organic material, while the irradiation rate reduced its abundance at high photon doses by a factor of 8. These results give insights on the impact of icy environment conditions in the evolution of astrophysical organic matter. [ABSTRACT FROM AUTHOR]

The Solar system planets are benchmarks for the planet formation theory. Yet two paradigms coexist for the four terrestrial planets: the prolonged collisional growth among planetesimals lasting |$\gt 100$|  million years (Myr) and the fast formation via planetesimals accreting pebbles within 10 Myr. Despite their dramatic difference, we can hardly tell which theory is more relevant to the true history of the terrestrial planets' formation. Here, we show that the Moon's origin puts stringent constraints on the pebble accretion scenario, rendering it less favourable. In the pebble accretion model, the one-off giant impact between proto-Earth and Theia rarely (probability |$\lt $| 1‰) occurs at the right timing and configuration for the Moon formation. Even if a potential impact happens by chance, giant impact simulations reveal perfect mixing between proto-Earth and Theia, leaving no room for the observed primordial Earth mantle heterogeneity and the compositional difference, though small, between Earth and the Moon. Thus, the Earth–Moon system along other terrestrial planets should preferably form from chaotic collisional growth in the inner Solar system. [ABSTRACT FROM AUTHOR]

Head-on giant impacts (collisions between planet-sized bodies) are frequently used to study the planet formation process as they present an extreme configuration where the two colliding bodies are greatly disturbed. With limited computing resources, focusing on these extreme impacts eases the burden of exploring a large parameter space. Results from head-on impacts are often then extended to study oblique impacts with angle corrections or used as initial conditions for other calculations, for example, the evolution of ejected debris. In this study, we conduct a detailed investigation of the thermodynamic and energy budget evolution of high-energy head-on giant impacts, entering the catastrophic impacts regime, for target masses between 0.001 and 12 M |$_{{\oplus }}$|⁠. We demonstrate the complex interplay of gravitational forces, shock dynamics, and thermodynamic processing in head-on impacts at high energy. Our study illustrates that frequent interactions of core material with the liquid side of the vapour curve could have cumulative effects on the post-collision remnants, leading to fragmentary disintegration occurring at lower impact energy. This results in the mass of the largest remnant diverging significantly from previously developed scaling laws. These findings suggest two key considerations: (1) head-on planetary collisions for different target masses do not behave similarly, so caution is needed when applying scaling laws across a broad parameter space; and (2) an accurate model of the liquid-vapour phase boundary is essential for modelling giant impacts. Our findings highlight the need for careful consideration of impact configurations in planetary formation studies, as head-on impacts involve a complex interplay between thermodynamic processing, shocks, gravitational forces, and other factors. [ABSTRACT FROM AUTHOR]

Water ice plays a crucial role throughout the different stages of planetary evolution and is abundant in the Universe. However, its presence and nature in debris discs of exoplanetary systems are not yet strongly established observationally. In this study, we quantify and discuss the impact of ice parameters such as volume fraction |${\mathcal {F}}_{\rm ice}$|⁠ , blow-out grain size, size distribution, and its phase on the observational appearance of debris discs, considering the diverse nature of these systems around stellar spectral types ranging from A to M. Our findings reveal that the prominent ice features at approximately 2.7 and 3.3  μ m depend on both the water ice fraction |${\mathcal {F}}_{\rm ice}$| and the scattering angle, with backscattering geometries yielding the most prominent signatures. When the phase function is considered and data are not background limited, strong forward and backward scattering (near edge-on discs) are expected to yield the strongest detections in images/spectra for A or F-type stars, while scattering angle matters less for later type stars. The Fresnel peak at 3.1  μ m serves as a viable discriminant for the transitional phase (crystalline/amorphous), while simultaneously constraining the water ice temperature. For JWST imaging, we find that the F 356 W and F 444 W filter combination is most effective for constraining the grain size distribution, while the F 356 W and F 277 W filter combination provides better constraints on the ice fraction |${\mathcal {F}}_{\rm ice}$| in debris discs. However, degeneracy between the grain size distribution and ice fraction when using photometric flux ratios means that obtaining robust constraints will likely require more than two filters, or spectroscopic data. [ABSTRACT FROM AUTHOR]

Particle–particle and particle–gas processes significantly impact planetary precursors such as dust aggregates and planetesimals. We investigate gas permeability (⁠|$\kappa$|⁠) in 12 granular samples, mimicking planetesimal dust regoliths. Using parabolic flights, this study assesses how gravitational compression – and lack thereof – influences gas permeation, impacting the equilibrium state of low-gravity objects. Transitioning between micro- and hyper-gravity induces granular sedimentation dynamics, revealing collective dust–grain aerodynamics. Our experiments measure |$\kappa$| across Knudsen number (Kn) ranges, reflecting transitional flow. Using mass and momentum conservation, we derive |$\kappa$| and calculate pressure gradients within the granular matrix. Key findings: (i) As confinement pressure increases with gravitational load and mass flow, |$\kappa$| and average pore space decrease. This implies that a planetesimal's unique dust-compaction history limits subsurface volatile outflows. (ii) The derived pressure gradient enables tensile strength determination for asteroid regolith simulants with cohesion. This offers a unique approach to studying dust-layer properties when suspended in confinement pressures comparable to the equilibrium state on planetesimals surfaces, which will be valuable for modelling their collisional evolution. (iii) We observe a dynamical flow symmetry breaking when granular material moves against the pressure gradient. This occurs even at low Reynolds numbers, suggesting that Stokes numbers for drifting dust aggregates near the Stokes–Epstein transition require a drag force modification based on permeability. [ABSTRACT FROM AUTHOR]

Context. When retrieving exoplanet atmospheric characteristics from spectroscopic observations, parameter estimation results strongly depend on the chosen forward model. In the era of the James Webb Space Telescope (JWST) and other next-generation facilities, the increased signal-to-noise ratio (S/N), wavelength coverage, and spectral resolution of observations warrant closer investigations into factors that could inadvertently bias the results of these retrievals. Aims. We aim to investigate the impact of utilising multi-point pressure–temperature (p–T) profiles of varying complexity on the retrieval of synthetically generated hot-Jupiter transmission spectra modelled after state-of-the-art observations of the hot Jupiter WASP-39 b with JWST. Methods. We performed homogenised atmospheric retrievals with the TauREx retrieval framework on a sample of synthetically generated transmission spectra, accounting for varying cases of underlying p–T profiles, cloud-top pressures, and expected noise levels. These retrievals are performed using a fixed-pressure multi-point p–T prescription with increasing complexity, ranging from isothermal to an eleven-point profile. We evaluated the performance of the retrievals based on the Bayesian model evidence, and the accuracy of the retrievals was compared to the known input parameters. Results. We find that performing atmospheric retrievals using an isothermal prescription for the pressure–temperature profile consistently results in wrongly retrieved atmospheric parameters when compared to the known input parameters. For an underlying p–T profile with a fully positive lapse rate, we find that a two-point profile is sufficient to retrieve the known atmospheric parameters, while under the presence of an atmospheric temperature inversion, we find that a more complex profile is necessary. Conclusions. Our investigation shows that, for a data quality scenario mirroring state-of-the-art observations of a hot Jupiter with JWST, an isothermal p–T prescription is insufficient to correctly retrieve the known atmospheric parameters. We find a model complexity preference dependent on the underlying pressure–temperature structure, but we argue that a p–T prescription on the complexity level of a four-point profile should be preferred. This represents the overlap between the lowest number of free parameters and the highest model preference in the cases investigated in this work. [ABSTRACT FROM AUTHOR]

Jupiter's icy moon Ganymede has a tenuous exosphere produced by sputtering and possibly sublimation of water ice. To date, only atomic hydrogen and oxygen have been directly detected in this exosphere. Here, we present observations of Ganymede's CO2 exosphere obtained with the James Webb Space Telescope. CO2 gas is observed over different terrain types, mainly over those exposed to intense Jovian plasma irradiation, as well as over some bright or dark terrains. Despite warm surface temperatures, the CO2 abundance over equatorial subsolar regions is low. CO2 vapor has the highest abundance over the north polar cap of the leading hemisphere, reaching a surface pressure of 1 pbar. From modeling we show that the local enhancement observed near 12 h local time in this region can be explained by the presence of cold traps enabling CO2 adsorption. However, whether the release mechanism in this high-latitude region is sputtering or sublimation remains unclear. The north polar cap of the leading hemisphere also has unique surface-ice properties, probably linked to the presence of the large atmospheric CO2 excess over this region. These CO2 molecules might have been initially released in the atmosphere after the radiolysis of CO2 precursors, or from the sputtering of CO2 embedded in the H2O ice bedrock. Dark terrains (regiones), more widespread on the north versus south polar regions, possibly harbor CO2 precursors. CO2 molecules would then be redistributed via cold trapping on ice-rich terrains of the polar cap and be diurnally released and redeposited on these terrains. Ganymede's CO2 exosphere highlights the complexity of surface-atmosphere interactions on Jupiter's icy Galilean moons. [ABSTRACT FROM AUTHOR]

Aims. Following several reports announcing the detection or non-detection of minor species above the clouds of Venus, we have searched for other possible signatures of PH3, HCN, and NH3 in the infrared range. Methods. Since 2012, we have performed ground-based observations of Venus in the thermal infrared at various wavelengths to monitor the behavior of SO2 and H2O at the cloud top. We have identified spectral intervals where transitions of PH3 (around 955 cm−1), HCN (around 747 cm−1), and NH3 (around 951cm−1) are present. Results. From the absence of any feature at these frequencies, we derive, on the disk-integrated spectrum, a 3-σ upper limit of 3 ppbv for the PH3 mixing ratio, 0.5 ppbv for HCN, and 0.3 ppbv for NH3, assuming that these species have a constant mixing ratio throughout the atmosphere. Maps of the Venus disk recorded at the center position of the lines show that there is no evidence for local detection anywhere over the Venus disk. Conclusions. Our results bring new constraints on the maximum abundance of these species at the cloud top and in the lower mesosphere of Venus. [ABSTRACT FROM AUTHOR]

Motivated by the observed ~30% variations in flux from the L7 dwarf VHS 1256 b, we subjected its time-resolved Hubble Space Telescope (HST) WFC3 spectra (measured in two epochs: 2018 and 2020), as well as medium-resolution Very Large Telescope (VLT) X-shooter and Early Release Science James Webb Space Telescope (JWST) spectra to a suite of both standard Bayesian (nested sampling) and machine-learning (random forest) retrievals. We find that both HST and VLT data require vertically varying abundance profiles of water in order to model the spectra accurately. Despite the large flux variations observed in the HST data, the temporal variability cannot be attributed to a single varying atmospheric property. The retrieved atmospheric quantities are consistent with being invariant across time. However, we find that model grids offer relatively poor fits to the measured HST spectra and are unsuitable for quantifying the temporal variability of atmospheric properties. Additionally, our analysis of JWST spectra using model grids indicates consistency in terms of the retrieved properties across different wavelength channels. Despite the temporal variability in flux, the retrieved properties between HST and VLT, as well those as between HST and JWST, are consistent within the respective posterior uncertainties. Such an outcome bodes well for future retrieval analyses of exoplanetary atmospheres, which are expected to exhibit weaker flux variations. [ABSTRACT FROM AUTHOR]

Context. The known population of short-period giant exoplanets around M-dwarf stars is slowly growing. These planets present an extraordinary opportunity for atmospheric characterisation and defy our current understanding of planetary formation. Furthermore, clouds and hazes are ubiquitous in warm exoplanets, but their behaviour is still poorly understood. Aims. We studied the case of a standard warm Jupiter around an M-dwarf star to show the opportunity of this exoplanet population for atmospheric characterisation. We aimed to derive the cloud, haze, and chemical budget of such planets using JWST. Methods. We leveraged a 3D global climate model, the generic PCM, to simulate the cloudy and cloud-free atmosphere of warm Jupiters around an M dwarf. We then post-processed our simulations to produce spectral phase curves and transit spectra as would be seen with JWST. Results. We show that, using the amplitude and offset of the spectral phase curves, we can directly infer the presence of clouds and hazes in the atmosphere of such giant planets. Chemical characterisation of multiple species is possible with an unprecedented signal- to-noise ratio, using the transit spectrum in one single visit. In such atmospheres, NH3 could be detected for the first time in a giant exoplanet. We make the case that these planets are key to understanding the cloud and haze budget in warm giants. Finally, such planets are targets of great interest for Ariel. [ABSTRACT FROM AUTHOR]

We present improved empirical density profiles of Uranus and interpret them in terms of their temperature and composition using a new random algorithm. The algorithm to determine the temperature and composition is agnostic with respect to the temperature gradient in non-isentropic regions and chooses amongst all possible gradients randomly that are stable against convection and correspond to an Equation of State (EoS) compatible composition. Our empirical models are based on an efficient implementation of the Theory of Figures (ToF) up to tenth order including a proper treatment of the atmosphere. The accuracy of tenth order ToF enables us to present accurate calculations of the gravitational moments of Uranus up to J14: J6 = (5.3078 ± 0.3312) 10−7, J8 = (−1.1114 ± 0.1391) 10−8, J10 = (2.8616 ± 0.5466) 10−10, J12 = (−8.4684 ± 2.0889) 10−12, and J14 = (2.7508 ± 0.7944) 10−13. We consider two interior models of Uranus that differ with respect to the maximal number of materials allowed per layer of Uranus (three versus four composition components). The case with three materials does not allow Hydrogen and Helium (H-He) in deeper parts of Uranus and results in a higher water (H2O) abundance which leads to lower central temperatures. On the other hand, the models with four materials allow H-He to be mixed into the deeper interior and lead to rock-dominated solutions. We find that these four composition components' models are less reliable due to the underlying empirical models' incompatibility with realistic Brunt frequencies. Most of our models are found to be either purely convective with the exception of boundary layers, or only convective in the outermost region above ~80% of the planets' radius rU. Almost all of our models possess a region ranging between ~(0.75–0.9) rU that is convective and consists of ionic H2O which could explain the generation of Uranus' magnetic field. [ABSTRACT FROM AUTHOR]

Context. More than 15 years after its landing on the surface of Titan, the data returned by the Huygens probe remain the only available in situ information on Titan's lower atmosphere and its methane content. Aims. In this work, we present a reanalysis of the Huygens probe data obtained by the Gas Chromatograph Mass Spectrometer (GCMS) instrument on board Huygens. GCMS measured the atmospheric composition almost continuously during the Huygens probe descent by acquiring mass spectra between 145 km of altitude and Titan's surface. We first focus on the recollection, reconstruction, and recalibration of the GCMS dataset to facilitate similar future work. Methods. We then reevaluate the methane vertical profile in Titan's lower atmosphere by applying novel mass spectra data-treatment methods to this dataset. Results. In addition to finding a slightly lower methane mixing ratio than those previously reported using GCMS measurements above the Huygens probe landing site, our work has revealed several kilometric to subkilometric-scale oscillations in the methane vertical profile below 30 km of altitude. Conclusions. We discuss several hypotheses that could explain these features, such as multiple layers of optically thin clouds or local convection cells, and strongly encourage the reanalysis of other Huygens datasets to further investigate these variations in the methane mixing ratio. [ABSTRACT FROM AUTHOR]

Aims. Following several reports announcing the detection or non-detection of minor species above the clouds of Venus, we have searched for other possible signatures of PH3, HCN, and NH3 in the infrared range. Methods. Since 2012, we have performed ground-based observations of Venus in the thermal infrared at various wavelengths to monitor the behavior of SO2 and H2O at the cloud top. We have identified spectral intervals where transitions of PH3 (around 955 cm−1), HCN (around 747 cm−1), and NH3 (around 951cm−1) are present. Results. From the absence of any feature at these frequencies, we derive, on the disk-integrated spectrum, a 3-σ upper limit of 3 ppbv for the PH3 mixing ratio, 0.5 ppbv for HCN, and 0.3 ppbv for NH3, assuming that these species have a constant mixing ratio throughout the atmosphere. Maps of the Venus disk recorded at the center position of the lines show that there is no evidence for local detection anywhere over the Venus disk. Conclusions. Our results bring new constraints on the maximum abundance of these species at the cloud top and in the lower mesosphere of Venus. [ABSTRACT FROM AUTHOR]

We report the spectroscopic confirmation and fundamental properties of TOI |$-$| 757 b, a mini |$-$| Neptune on a 17.5 |$-$| d orbit transiting a bright star (⁠|$V\, =\, 9.7$| mag) discovered by the TESS mission. We acquired high |$-$| precision radial velocity measurements with the HARPS, ESPRESSO, and PFS spectrographs to confirm the planet detection and determine its mass. We also acquired space |$-$| borne transit photometry with the CHEOPS space telescope to place stronger constraints on the planet radius, supported with ground |$-$| based LCOGT photometry. WASP and KELT photometry were used to help constrain the stellar rotation period. We also determined the fundamental parameters of the host star. We find that TOI |$-$| 757 b has a radius of |$R_{\mathrm{p}} = 2.5 \pm 0.1 R_{\oplus }$| and a mass of |$M_{\mathrm{p}} = 10.5^{+2.2}_{-2.1} M_{\oplus }$|⁠ , implying a bulk density of |$\rho _{\text{p}} = 3.6 \pm 0.8$| g cm |$^{-3}$|⁠. Our internal composition modelling was unable to constrain the composition of TOI |$-$| 757 b, highlighting the importance of atmospheric observations for the system. We also find the planet to be highly eccentric with e = 0.39 |$^{+0.08}_{-0.07}$|⁠ , making it one of the very few highly eccentric planets among precisely characterized mini |$-$| Neptunes. Based on comparisons to other similar eccentric systems, we find a likely scenario for TOI |$-$| 757 b's formation to be high eccentricity migration due to a distant outer companion. We additionally propose the possibility of a more intrinsic explanation for the high eccentricity due to star |$-$| star interactions during the earlier epoch of the Galactic disc formation, given the low metallicity and older age of TOI |$-$| 757. [ABSTRACT FROM AUTHOR]

This second paper presents an in-depth analysis of the composition of the planetary material that has been accreted on to seven white dwarfs with circumstellar dust and gas emission discs with abundances reported in Rogers et al. The white dwarfs are accreting planetary bodies with a wide range of oxygen, carbon, and sulphur volatile contents, including one white dwarf that shows the most enhanced sulphur abundance seen to date. Three white dwarfs show tentative evidence (2–3 |$\sigma$|⁠) of accreting oxygen-rich material, potentially from water-rich bodies, whilst two others are accreting dry, rocky material. One white dwarf is accreting a mantle-rich fragment of a larger differentiated body, whilst two white dwarfs show an enhancement in their iron abundance and could be accreting core-rich fragments. Whilst most planetary material accreted by white dwarfs display chondritic or bulk Earth-like compositions, these observations demonstrate that core-mantle differentiation, disruptive collisions, and the accretion of core-mantle differentiated material are important. Less than 1 per cent of polluted white dwarfs host both observable circumstellar gas and dust. It is unknown whether these systems are experiencing an early phase in the disruption and accretion of planetary bodies, or alternatively if they are accreting larger planetary bodies. From this work there is no substantial evidence for significant differences in the accreted refractory abundance ratios for those white dwarfs with or without circumstellar gas, but there is tentative evidence for those with circumstellar gas discs to be accreting more water rich material which may suggest that volatiles accrete earlier in a gas-rich phase. [ABSTRACT FROM AUTHOR]

White dwarf atmospheres are frequently polluted by material from their own planetary systems. Absorption features from Ca, Mg, Fe, and other elements can provide unique insights into the provenance of this exoplanetary material, with their relative abundances being used to infer accretion of material with core- or mantle-like composition. Across the population of white dwarfs, the distribution of compositions reveals the prevalence of geological and collisional processing across exoplanetary systems. By predicting the distribution of compositions in three evolutionary scenarios, this work assesses whether they can explain current observations. We consider evolution in an asteroid belt analogue, in which collisions between planetary bodies that formed an iron core lead to core- or mantle-rich fragments. We also consider layer-by-layer accretion of individual bodies, such that the apparent composition of atmospheric pollution changes during the accretion of a single body. Finally, we consider that compositional spread is due to random noise. We find that the distribution of Ca, Fe, and Mg in a sample of 202 cool DZs is consistent with the random noise scenario, although 7 individual systems show strong evidence of core-mantle differentiation from additional elements and/or low noise levels. Future surveys that detect multiple elements in each of a few hundred white dwarfs, with well-understood biases, have the potential to confidently distinguish between the three models. [ABSTRACT FROM AUTHOR]

ABSTRACT: The composition of forming planets is strongly affected by the protoplanetary disc’s thermal structure. This thermal structure is predominantly set by dust radiative transfer and viscous (accretional) heating and can be impacted by gaps – regions of low dust and gas density that can occur when planets form. The effect of variations in dust surface density on disc temperature has been poorly understood to date. In this work, we use the radiative transfer code MCMax to model the 2D dust thermal structure with individual gaps corresponding to planets with masses of 0.1 MJ –5 MJ and orbital radii of 3, 5, and 10 au. Low dust opacity in the gap allows radiation to penetrate deeper and warm the mid-plane by up to 16 K, but only for gaps located in the region of the disc where stellar irradiation is the dominant source of heating. In viscously heated regions, the mid-plane of the gap is relatively cooler by up to 100 K. Outside of the gap, broad radial oscillations in heating and cooling are present due to disc flaring. These thermal features affect local dust–gas segregation of volatile elements (H2O, CH4, CO2, and CO). We find that icelines experience dramatic shifts relative to gapless models: up to 6.5 au (or 71 per cent) closer to the star and 4.3 au (or 100 per cent) closer to the mid-plane. While quantitative predictions of iceline deviations will require more sophisticated models, which include transport, sublimation/condensation kinetics, and gas–dust thermal decoupling in the disc atmosphere, our results suggest that planet-induced iceline variations represent a potential feedback from the planet on to the composition of material it is accreting.

A systematic, population-level discrepancy exists between the densities of exoplanets whose masses have been measured with transit timing variations (TTVs) versus those measured with radial velocities (RVs). Since the TTV planets are predominantly nearly resonant, it is still unclear whether the discrepancy is attributed to detection biases or to astrophysical differences between the nearly resonant and non resonant planet populations. We defined a controlled, unbiased sample of 36 sub-Neptunes characterised by Kepler, TESS, HARPS, and ESPRESSO. We found that their density depends mostly on the resonant state of the system, with a low probability (of 0.002−0.001+0.010) that the mass of (nearly) resonant planets is drawn from the same underlying population as the bulk of sub-Neptunes. Increasing the sample to 133 sub-Neptunes reveals finer details: the densities of resonant planets are similar and lower than non-resonant planets, and both the mean and spread in density increase for planets that are away from resonance. This trend is also present in RV-characterised planets alone. In addition, TTVs and RVs have consistent density distributions for a given distance to resonance. We also show that systems closer to resonances tend to be more co-planar than their spread-out counterparts. These observational trends are also found in synthetic populations, where planets that survived in their original resonant configuration retain a lower density; whereas less compact systems have undergone post-disc giant collisions that increased the planet's density, while expanding their orbits. Our findings reinforce the claim that resonant systems are archetypes of planetary systems at their birth. [ABSTRACT FROM AUTHOR]

With four companions at separations from 16 to 71 au, HR 8799 is a unique target for direct imaging, presenting an opportunity for a comparative study of exoplanets with a shared formation history. Combining new VLTI/GRAVITY observations obtained within the ExoGRAVITY program with archival data, we performed a systematic atmospheric characterisation across all four planets. We explored different levels of model flexibility to understand the temperature structure, chemistry, and clouds of each planet using both petitRADTRANS atmospheric retrievals and fits to self-consistent radiative–convective equilibrium models. Using Bayesian model averaging to combine multiple retrievals (a total of 89 across all four planets), we find that the HR 8799 planets are highly enriched in metals, with [M/H] ≳1, and have stellar to superstellar atmospheric C/O ratios. The C/O ratio increases with increasing separation from 0.55−0.10+0.12 for d to 0.78−0.04+0.03 for b, with the exception of the innermost planet, which has a C/O ratio of 0.87 ± 0.03. Such high metallicities are unexpected for these massive planets, and challenge planet-formation models. By retrieving a quench pressure and using a disequilibrium chemistry model, we derive vertical mixing strengths compatible with predictions for high-metallicity, self-luminous atmospheres. Bayesian evidence comparisons strongly favour the presence of HCN in HR 8799 c and e, as well as CH4 in HR 8799 c, with detections at > 5σ confidence. All of the planets are cloudy, with no evidence of patchiness. The clouds of c, d, and e are best fit by silicate clouds lying above a deep iron cloud layer, while the clouds of the cooler HR 8799 b are more likely composed of Na2S. With well-defined atmospheric properties, future exploration of this system is well positioned to unveil further details of these planets, extending our understanding of the composition, structure, and formation history of these siblings. [ABSTRACT FROM AUTHOR]

The characterization of super-Earth- to Neptune-sized exoplanets relies heavily on our understanding of their formation and evolution. In this study, we link a model of planet formation by pebble accretion to the planets' long-term observational properties by calculating the interior evolution, starting from the dissipation of the protoplanetary disk. We investigate the evolution of the interior structure in 5–20 M⊕ planets, accounting for silicate redistribution caused by convective mixing, rainout (condensation and settling), and mass loss. Specifically, we have followed the fate of the hot silicate vapor that remained in the planet's envelope after planet formation as the planet cools. We find that disk dissipation is followed by a rapid contraction of the envelope from the Hill or Bondi radius to about one-tenth of that size within 10 Myr. Subsequent cooling leads to substantial growth of the planetary core through silicate rainout accompanied by inflated radii, in comparison to the standard models of planets that formed with core-envelope structure. We examined the dependence of rainout on the planet's envelope mass, on the distance from its host star, on its silicate mass, and on the atmospheric opacity. We find that the population of planets that formed with polluted envelopes can be roughly divided into three groups based on the mass of their gas envelopes: bare rocky cores that have shed their envelopes, super-Earth planets with a core-envelope structure, and Neptune-like planets with diluted cores that undergo gradual rainout. For polluted planets that formed with envelope masses below 0.4 M⊕, we anticipate that the inflation of the planet's radius caused by rainout will enhance the mass loss by a factor of 2–8 compared to planets with unpolluted envelopes. Our model bridges the gap between the predicted composition gradients in massive planets and the core-envelope structure in smaller planets. [ABSTRACT FROM AUTHOR]

Aims. Impacts between differentiated planetesimals are ubiquitous in protoplanetary discs and may mix materials from the core, mantle, and crust of planetesimals, thus forming stony-iron meteorites. The surface composition of the asteroid (16) Psyche represents a mixture of metal and non-metal components. However, the velocities, angles, and outcome regimes of impacts that mixed metal and silicate from different layers of planetesimals are debated. Our aim is to investigate the impacts between planetesimals that can mix large amounts of metal and silicate, and the mechanism of stony-iron meteorite formation. Methods. We used smooth particle hydrodynamics to simulate the impacts between differentiated planetesimals with various initial conditions that span different outcome regimes. In our simulations, the material strength was included and the effects of the states of planetesimal cores were studied. Using a statistical approach, we quantitatively analysed the distributions of metal and silicate after impacts. Results. Our simulations modelled the mass, depth, and sources of the metal–silicate mixture in different impact conditions. Our results suggest that the molten cores in planetesimals could facilitate mixing of metal and silicate. Large amounts of the metal–silicate mixture could be produced by low-energy accretional impacts and high-energy erosive impacts in the largest impact remnant, and by hit-and-run and erosive impacts in the second-largest impact remnant. After impact, most of the metal-silicate mixture was buried at depth, consistent with the low cooling rates of stony-iron meteorites. Our results indicate that mesosiderites potentially formed in an erosive impact, while pallasites potentially formed in an accretional or hit-and-run impact. The mixing of metal and non-metal components on Psyche may also be the result of impacts. [ABSTRACT FROM AUTHOR]

The radius valley, i.e. a dearth of planets with radii between 1.5 and 2 Earth radii, provides insights into planetary formation and evolution. Using homogenously revised planetary parameters from Kepler 1-min short cadence light curves, we remodel transits of 72 small planets mostly orbiting low-mass stars, improving the precision and accuracy of planet parameters. By combining this sample with a similar sample of planets around higher mass stars, we determine the depth of the radius valley as a function of stellar mass. We find that the radius valley is shallower for low-mass stars compared to their higher mass counterparts. Upon comparison, we find that theoretical models of photoevaporation underpredict the number of planets observed inside the radius valley for low-mass stars: with decreasing stellar mass, the predicted fraction of planets inside the valley remains approximately constant whereas the observed fraction increases. We argue that this provides evidence for the presence of icy planets around low-mass stars. Alternatively, planets orbiting low-mass stars undergo more frequent collisions and scatter in the stars' high-energy output may also cause planets to fill the valley. We predict that more precise mass measurements for planets orbiting low-mass stars would be able to distinguish between these scenarios. [ABSTRACT FROM AUTHOR]

Ultrahot Jupiters (UHJs) undergo intense irradiation by their host stars and are expected to experience non-local thermodynamic equilibrium (NLTE) effects in their atmospheres. Such effects are computationally intensive to model but, at the low pressures probed by high-resolution cross-correlation spectroscopy (HRCCS), can significantly impact the formation of spectral lines. The UHJ WASP-121 b exhibits a highly inflated atmosphere, making it ideal for investigating the impact of NLTE effects on its transmission spectrum. Here, we formally introduce cloudy for exoplanets , a cloudy -based modelling code, and use it to generate 1D LTE and NLTE atmospheric models and spectra to analyse archival HARPS WASP-121 b transmission spectra. We assessed the models using two HRCCS methods: (i) Pearson cross-correlation, and (ii) a method that aims to match the average observed line depth for given atmospheric species. All models result in strong detections of Fe  i (7.5 < S / N < 10.5). However, the highest S/N model (LTE) does not agree with the best-matching model of the average line depth (NLTE). We also find degeneracy, such that increasing the isothermal temperature and metallicity of the LTE models can produce average line depths similar to cooler, less metal rich NLTE models. Thus, we are unable to conclusively remark on the presence of NLTE effects in the atmosphere of WASP-121 b. We instead highlight the need for standardized metrics in HRCCS that enable robust statistical assessment of complex physical models, e.g. NLTE or 3D effects, that are currently too computationally intensive to include in HRCCS atmospheric retrievals. [ABSTRACT FROM AUTHOR]

Anharmonic quantum chemical computations reveal a strong, narrow (width = 0.075 |$\mu$| m) band in the 4.3–4.5 |$\mu$| m region of the absorption spectra of the cyano-substituted polycyclic aromatic hydrocarbons (CN-PAHs) cyanonaphthalene, cyanoanthracene, cyanophenanthrene, and cyanopyrene. This narrow window with intense IR lines implies that CN-PAHs of various shapes and sizes offer little variation in both wavelength and intensity in this region. Subsequently, this band can be used as a tracer for CN-PAHs. The distinct features making up the band are assigned to mixed vibrational states consisting of the CN stretch fundamental and various combination bands, including in-plane CH bends, CC skeletal bends, and CC skeletal breathing motions. The extraordinarily large intrinsic intensity of the fundamental CN stretch is redistributed to nearby states via anharmonic coupling, which is readily captured when using second order vibrational perturbation theory with resonance polyad matrices. This redistribution of intensity leads to a complex spectrum. The intense bands in this wavelength region may contribute to the baseline continuum and undulating macroscopic structure seen in recent JWST NIRSpec observations. [ABSTRACT FROM AUTHOR]

JWST observations are leading to important new insights into exoplanetary atmospheres through transmission spectroscopy. In order to harness the full potential of the broad spectral range and high sensitivity of JWST , atmospheric retrievals of exoplanets require a high level of robustness and accuracy in the underlying models. We present the VIRA retrieval framework which implements a range of modelling and inference capabilities motivated by early JWST observations of exoplanet transmission spectra. This includes three complementary approaches to modelling atmospheric composition, three atmospheric aerosol models, including a physically motivated Mie scattering approach, and consideration of correlated noise. VIRA enables a cascading retrieval architecture involving a sequence of retrievals with increasing sophistication. We demonstrate VIRA using a JWST transmission spectrum of the hot Saturn WASP-39b in the ∼1–5  |$\mu$| m range. In addition to confirming prior chemical inferences, we retrieve molecular abundances for H2O, CO, CO2, SO2, and H2S, resulting in supersolar elemental abundances of log(O/H) = −2.0 ± 0.2, log(C/H) = −2.1 ± 0.2, and log(S/H) = −3.6 ± 0.2, along with C/O and S/O ratios of |$0.83^{+0.05}_{-0.07}$| and |$0.029^{+0.012}_{-0.009}$|⁠ , respectively, in the free chemistry case. The abundances correspond to |$20.1^{+10.5}_{-8.1}\times$|⁠ , |$28.2^{+16.3}_{-12.1}\times$|⁠ , and |$20.8^{+10.3}_{-7.5}\times$| solar values for O/H, C/H, and S/H, respectively, compared to C/H = 8.67 ± 0.35 × solar for Saturn. Our results demonstrate how JWST transmission spectroscopy combined with retrieval frameworks like VIRA can measure multi-elemental abundances for giant exoplanets and enable comparative characterization with solar system planets. [ABSTRACT FROM AUTHOR]

Numerous chemical constraints have been possible for exoplanetary atmospheres thanks to high-resolution spectroscopy (HRS) from ground-based facilities as well as low-resolution spectroscopy (LRS) from space. These two techniques have complementary strengths, and hence combined HRS and LRS analyses have the potential for more accurate abundance constraints and increased sensitivity to trace species. In this work, we retrieve the atmosphere of the ultra-hot Jupiter WASP-76 b, using high-resolution CARMENES/CAHA (Calar Alto high-Resolution search for M dwarfs with Exoearths with Near-infrared and optical Échelle Spectrographs) and low-resolution Hubble Space Telescope 's (HST) Wide Field Camera 3 (WFC3) and Spitzer observations of the primary eclipse. As such, hot planets are expected to have a substantial fraction of H2O dissociated, we conduct retrievals including both H2O and OH. We explore two retrieval models, one with self-consistent treatment of H2O dissociation and another where H2O and OH are vertically homogeneous. Both models constrain H2O and OH, with H2O primarily detected by LRS and OH through HRS, highlighting the strengths of each technique and demonstrating the need for combined retrievals to fully constrain chemical compositions. We see only a slight preference for the H2O-dissociation model given that the photospheric constraints for both are very similar, indicating |$\log (\mathrm{OH/H_2O}) = 0.7^{+0.3}_{-0.3}$| at 1.5 mbar, showing that the majority of the H2O in the photosphere is dissociated. However, the bulk O/H and C/O ratios inferred from the models differs significantly, and highlights the challenge of constraining bulk compositions from photospheric abundances with strong vertical chemical gradients. Further observations with JWST and ground-based facilities may help shed more light on these processes. [ABSTRACT FROM AUTHOR]

We report the confirmation and mass determination of a mini-Neptune transiting the M3.5 V star TOI-4438 (G 182-34) every 7.44 days. A transit signal was detected with NASA's TESS space mission in the sectors 40, 52, and 53. In order to validate the planet TOI-4438 b and to determine the system properties, we combined TESS data with high-precision radial velocity measurements from the CARMENES spectrograph, spanning almost one year, and ground-based transit photometry. We found that TOI-4438 b has a radius of Rb = 2.52 ± 0.13 R⊕ (5% precision), which together with a mass of Mb = 5.4 ± 1.1 M⊕ (20% precision), results in a bulk density of ρb = 1.85−0.44+0.51 g cm−3 (~28% precision), aligning the discovery with a volatile-rich planet. Our interior structure retrieval with a pure water envelope yields aminimum water mass fraction of 46% (1σ). TOI-4438 b is a volatile-rich mini-Neptune with likely H/He mixed with molecules, such as water, CO2, and CH4. The primary star has a J-band magnitude of 9.7, and the planet has a high transmission spectroscopy metric (TSM) of 136 ± 13. Taking into account the relatively warm equilibrium temperature of Teq = 435 ± 15 K, and the low activity level of its host star, TOI-4438 b is one of the most promising mini-Neptunes around an M dwarf for transmission spectroscopy studies. [ABSTRACT FROM AUTHOR]

Context. Out of the more than 5000 detected exoplanets, a considerable number belong to a category called "mini-Neptunes". Interior models of these planets suggest that they have primordial H–He-dominated atmospheres. As this type of planet is not found in the Solar System, understanding their formation is a key challenge in planet formation theory. Unfortunately, quantifying how much H–He planets have, based on their observed mass and radius, is impossible due to the degeneracy of interior models. Aims. Another approach to estimating the range of possible primordial envelope masses is to use formation theory. As different assumptions in planet formation can heavily influence the nebular gas accretion rate of small planets, it is unclear how large the envelope of a protoplanet should be. We explore the effects that different assumptions regarding planet formation have on the nebular gas accretion rate, particularly by exploring the way in which solid material interacts with the envelope. This allows us to estimate the range of possible post-formation primordial envelopes. Thereby, we demonstrate the impact of envelope enrichment on the initial primordial envelope, which can be used in evolution models. Methods. We applied formation models that include different solid accretion rate prescriptions. Our assumption is that mini-Neptunes form beyond the ice line and migrate inward after formation; thus, we formed planets in situ at 3 and 5 au. We considered that the envelope can be enriched by the accreted solids in the form of water. We studied how different assumptions and parameters influence the ratio between the planet's total mass and the fraction of primordial gas. Results. The primordial envelope fractions for low- and intermediate-mass planets (total mass below 15 M⊕) can range from 0.1% to 50%. Envelope enrichment can lead to higher primordial mass fractions. We find that the solid accretion rate timescale has the largest influence on the primordial envelope size. Conclusions. Rates of primordial gas accretion onto small planets can span many orders of magnitude. Planet formation models need to use a self-consistent gas accretion prescription. [ABSTRACT FROM AUTHOR]

The number of super-Earth and mini-Neptune planet discoveries has increased significantly in the last two decades thanks to transit and radial velocity (RV) surveys. When it is possible to apply both techniques, we can characterise the internal composition of exoplanets, which in turn provides unique insights on their architecture, formation and evolution. We performed a combined photometric and RV analysis of TOI-238 (TYC 6398-132-1), which has one short-orbit super-Earth planet candidate announced by NASA's TESS team. We aim to confirm its planetary nature using radial velocities taken with the ESPRESSO and HARPS spectrographs, to measure its mass, and to detect the presence of other possible planetary companions. We carried out a joint analysis by including Gaussian processes and Keplerian orbits to account for the stellar activity and planetary signals simultaneously. We detected the signal induced by TOI-238 b in the RV time series, and the presence of a second transiting planet, TOI-238 c, whose signal appears in RV and TESS data. TOI-238 b is a planet with a radius of 1.402−0.086+0.084R⊕ and a mass of 3.40−0.45+0.46M⊕. It orbits at a separation of 0.02118 ± 0.00038 au of its host star, with an orbital period of 1.2730988 ± 0.0000029 days, and has an equilibrium temperature of 1311 ± 28 K. TOI-238 c has a radius of 2.18 ± 0.18 R⊕ and a mass of 6.7 ± 1.1 M⊕. It orbits at a separation of 0.0749 ± 0.0013 au of its host star, with an orbital period of 8.465652 ± 0.000031 days, and has an equilibrium temperature of 696 ± 15 K. The mass and radius of planet b are fully consistent with an Earth-like composition, making it a likely rocky super-Earth. Planet c could be a water-rich planet or a rocky planet with a small H-He atmosphere. [ABSTRACT FROM AUTHOR]

Context. The bulk abundances of CHNOS-bearing species of a planet have a profound effect on its interior structure and evolution. Therefore, it is key to investigate the behavior of the local abundances of these elements in the solid phase in the earliest stages of planet formation, where micrometer-sized dust grows into larger and larger aggregates. However, the physical and chemical processes occurring in planet-forming disks that shape these abundances are highly coupled and nonlocal. Aims. We aim to quantify the effects of the interplay between dynamical processes (turbulent diffusion, dust settling and radial drift), collision processes (coagulation and fragmentation), and the adsorption and desorption of ices on the abundances of CHNOS in local disk solids as a function of position throughout the planet-forming region. Methods. We used SHAMPOO (Stochastic Monomer Processor), which tracks the ice budgets of CHNOS-bearing molecules of a dust monomer as it undergoes nonlocal disk processing in a Class I disk. We used a large set of individual monomer evolutionary trajectories to make inferences about the properties of the local dust populations via a stochastic analysis of 64 000 monomers on a preexisting spatial grid. Results. We find that spatially, monomers can travel larger distances farther out in the disk, leading to a larger spread in positions of origin for a dust population at, for example, r = 50 AU compared to r = 2 AU. However, chemically, the inner disk (r ≲ 10 AU) is more nonlocal due to the closer spacing of ice lines in this disk region. Although to zeroth order the bulk ice mantle composition of icy dust grains remains similar compared to a fully local dust population, the ice mass associated with individual chemical species can change significantly. The largest differences with local dust populations were found near ice lines where the collisional timescale is comparable to the adsorption and desorption timescales. Here, aggregates may become significantly depleted in ice as a consequence of microscopic collisional mixing, a previously unknown effect where monomers are stored away in aggregate interiors through rapid cycles of coagulation and fragmentation. Conclusions. Nonlocal ice processing in a diffusion-dominated, massive, smooth disk has the most significant impact on the inner disk (r ≲ 10 AU). Furthermore, microscopic collisional mixing can have a significant effect on the amounts of ice of individual species immediately behind their respective ice lines. This suggests that ice processing is highly coupled to collisional processing in this disk region, which implies that the interiors of dust aggregates must be considered and not just their surfaces. [ABSTRACT FROM AUTHOR]

We present the discovery and characterization of two warm mini-Neptunes transiting the K3V star TOI-815 in a K–M binary system. Analysis of its spectra and rotation period reveal the star to be young, with an age of 200−200+400 Myr. TOI-8l5b has a 11.2-day period and a radius of 2.94 ± 0.05 R⊕ with transits observed by TESS, CHEOPS, ASTEP, and LCOGT. The outer planet, TOI-8l5c, has a radius of 2.62 ± 0.10 R⊕, based on observations of three nonconsecutive transits with TESS; targeted CHEOPS photometry and radial velocity follow-up with ESPRESSO were required to confirm the 35-day period. ESPRESSO confirmed the planetary nature of both planets and measured masses of 7.6 ± 1.5 M⊕ (ρP = 1.64−0.31+0.33 g cm−3) and 23.5 ± 2.4 M⊕ (ρP = 7.2−1.0+1.1 g cm−3), respectively. Thus, the planets have very different masses, which is unusual for compact multi-planet systems. Moreover, our statistical analysis of mini-Neptunes orbiting FGK stars suggests that weakly irradiated planets tend to have higher bulk densities compared to those undergoing strong irradiation. This could be ascribed to their cooler atmospheres, which are more compressed and denser. Internal structure modeling of TOI-815b suggests it likely has a H-He atmosphere that constitutes a few percent of the total planet mass, or higher if the planet is assumed to have no water. In contrast, the measured mass and radius of TOI-815c can be explained without invoking any atmosphere, challenging planetary formation theories. Finally, we infer from our measurements that the star is viewed close to pole-on, which implies a spin-orbit misalignment at the 3σ level. This emphasizes the peculiarity of the system's orbital architecture, and probably hints at an eventful dynamical history. [ABSTRACT FROM AUTHOR]

Context. The CO2-dominated thick atmosphere of Venus coexists with an ionosphere that is mainly formed, on the dayside, via the ionization of atmospheric neutrals by solar extreme ultraviolet and soft X-ray photons. Despite extensive modeling efforts that have reproduced the electron distribution reasonably well, we note two main shortcomings with respect to prior studies. The effects of pro-tonation and Coulomb interaction are crucial to unveiling the structure and composition of the Venusian ionosphere. Aims. We evaluate the role of protonated species on the structure of the dayside Venusian ionosphere for the first time. We also evaluate the role of ion-ion Coulomb collisions, which are neglected in many existing models. Methods. Focusing on the solar minimum condition for which the effect of protonation is expected to be more prominent, we constructed a detailed one-dimensional photochemical model for the dayside Venusian ionosphere, incorporating more than 50 ion and neutral species (of which 17 are protonated species), along with the most thorough chemical network to date. We included both ion-neutral and ion-ion Coulomb collisions. Photoelectron impact processes were implemented with a two-stream kinetic model. Results. Our model reproduces the observed electron distribution reasonably well. The model indicates that protonation tends to diverge the ionization flow into more channels via a series of proton transfer reactions along the direction of low to high proton affinities for parent neutrals. In addition, the distribution of O2+ is enhanced by protonation by a factor of nearly 2 at high altitudes, where it is efficiently produced via the reaction between O and OH+. We find that Coulomb collisions influence the topside Venusian ionosphere not only directly by suppressing ion diffusion, but also indirectly by modifying ion chemistry. Two ion groups can be distinguished in terms of the effects of Coulomb collisions: one group preferentially produced at high altitudes and accumulated in the topside ionosphere, which is to be compared with another group that is preferentially produced at low altitudes and, instead, depleted in the topside ionosphere. Conclusions. Both protonation and Coulomb collisions have appreciable impacts on the topside Venusian ionosphere, which account for many of the significant differences in the model ion distribution between this study and early calculations. [ABSTRACT FROM AUTHOR]

During protoplanetary disk formation, dust grains located in the outer disk retain their pristine icy composition, while solids in the inner stellar-heated disk undergo volatile loss. This process may have left a fossil record in Solar System material, showing different nucleosynthetic imprints that have been attributed to different degrees of thermal processing. However, it remains unclear how a large mass fraction of thermally processed inner-disk pebbles is produced and how these grains are subsequently transported throughout the disk. In this work, we numerically investigate the evolution in time of a two-component pebble disk consisting of both pristine pebbles and those that underwent ice sublimation. We find that stellar outbursts exceeding 1000 times the solar luminosity are efficient in thermally altering, through ice sublimation, a large mass fraction of pebbles (around 80%). After the establishment of this initial radial dust composition gradient throughout the disk, the subsequent mixing and inward drift of pristine outer-disk pebbles alter the inner disk bulk composition from processed to more unprocessed in time. Therefore, if processed pebbles without ice mantles have an isotopic composition similar to ureilite meteorites from the inner Solar System, inner-disk minor bodies forming from the early pebble flux (<1 Myr) will be isotopically ureilite-like, while later-formed bodies will be increasingly admixed with the signature of the lateincoming, CI chondrite-like unprocessed pebbles. This appears to be largely consistent with the trend seen between the accretion age of different meteoric classes and their different stable isotope composition anomalies (in μ54Cr, μ48Ca, μ30Si, and μ58Ni), but further work may be needed to explain the role of isotopically anomalous refractory inclusions and anomaly trends in other elements. Our findings further support an early thermal processing of ice mantles via stellar outbursts that are common around young Sun-like stars. [ABSTRACT FROM AUTHOR]

Context. A number of bodies in the Solar System are characterized by dark surfaces, from carbonaceous asteroids to the enigmatic surface of Phobos and Deimos. Our understanding of the spectroscopic behavior of low-albedo surfaces remains incomplete. To improve the interpretation of remote sensing data, laboratory studies continue to serve as a pivotal tool for unveiling the physical state and composition of such surfaces. Aims. Several processes can be simulated in the laboratory, however, the preparation and analysis of a complex mixing of analog material is one of the most fundamental among them, while also being one of the most complex when multiple components are used. In this work, we aim to study how dark material mixed with basaltic material at different grain sizes can affect the spectroscopic features from the near- to mid- infrared (1.25–25 µm). Methods. Our sample set includes four series of basaltic mix (feldspar and pyroxene) at different grain sizes from <50 µm to 1000 µm, mixed with amorphous carbon at increasing weight percentages ranging from 1% to 50%. We analyzed several features on the spectrum of each mineral mixture. In particular, we investigated the behavior of the: (i) near-infrared slope; (ii) 2.7 µm OH-stretching band; (iii) Christiansen features; and (iv) Reststrahlen band and Transparency feature. Results. The measurements presented in this work, which take into account a large wavelength range for the first time, point toward a critical effect of dark material, but with a different outcomes for each grain size. Some of the most interesting results involve the slope trend of modification with dark material and the variant behavior of the Reststrahlen band and Transparency feature. Conclusions. This dataset will offer a key support in the interpretation of data collected on dark surfaces by past and future space missions. This knowledge will be also important in the context of linking analyses of returned samples with remote sensing data collected on planetary surfaces. [ABSTRACT FROM AUTHOR]

Context. Understanding the formation history of planets is one of the goals of studying exoplanet atmospheres. The atmospheric composition of planets can provide insights into the formation pathways of planets. Even though the mapping of the atmospheric composition onto a formation pathway is not unambiguous, with the increasing sensitivity of modern instruments, we can derive promising constraints. Aims. In this work, we aim to understand the formation pathway of WASP-39b. We discuss whether the detection of SO2 in its atmosphere would impact our understanding of the formation of the planet and whether it enables us to determine the formation pathway of the planet with greater accuracy. Methods. We used the JWST transit observation of the planet together with the available HST and Spitzer observations. We used a formation model coupled with a radiative transfer retrieval model to derive the planet's atmospheric characteristics and formation history. Furthermore, we used a photochemical model to derive the impact of photochemistry on the atmosphere of the planet. Results. In this work, we show that the planet is most likely to have initiated beyond the CO2 ice line of its natal disk. Furthermore, the planet is likely to have have accreted some planetesimals during its formation. We show that the sulfur abundance in the atmosphere of the planet is probably lower than 2.27 × 10−4. This abundance indicates that the planet is likely to exhibit a lower metallicity than suggested by the retrievals. Furthermore, such an abundance for sulfur is more likely if WASP-39b had been formed beyond the CO ice line of its natal disk. [ABSTRACT FROM AUTHOR]

The number of discovered exoplanets now exceeds 5500 allowing statistical analyses of planetary systems. Multi-planet systems are mini-laboratories of planet formation and evolution, and analysing their system architectures can help us to constrain the physics of these processes. Recent works have found evidence of significant intrasystem uniformity in planet properties such as radius, mass, and orbital spacing, collectively termed 'peas in a pod' trends. In particular, correlations in radius and mass have been interpreted as implying uniformity in planet bulk density and composition within a system. However, the samples used to assess trends in mass tend to be small and biased. In this paper, we re-evaluate correlations in planet properties in a large sample of systems with at least two planets for which mass and radius have been directly measured, and therefore bulk density can be calculated. Our sample was assembled using the most up-to-date exoplanet catalogue data, and we compute the relevant statistics while using a procedure to 'weight' the data points according to measurement precision. We find a moderate correlation in radius and a weak correlation in the densities of adjacent planets. However, masses of neighbouring planets show no overall correlation in our main sample and a weak correlation among pairs of planets similar in size or pairs restricted to Mp<100 M⊕, Rp<10 R⊕. Similarly, we show that the intrasystem dispersion in radius is typically less than that in mass and density. We identify ranges in stellar host properties that correlate with stronger uniformity in pairs of adjacent planets: low Teff for planet masses, and low metallicity and old age for planet densities. Furthermore, we explore whether peas in a pod trends extend into planet compositions or interior structures. For small neighbouring planets with similar radii, we show that their masses and interior structures are often disparate, indicating that even within the same system, similarity in radii is not necessarily a good proxy for similarity in composition or the physical nature of the planets. [ABSTRACT FROM AUTHOR]

Molecular mapping is a supervised method exploiting the spectral diversity of integral field spectrographs to detect and characterise resolved exoplanets blurred into the stellar halo. We present an update to the method, aimed at removing the stellar halo and the nuisance of telluric features in the datacubes and accessing a continuum-subtracted spectra of the planets at R ~ 4000. We derived the planet atmosphere properties from a direct analysis of the planet telluric-corrected absorption spectrum. We applied our methods to the SINFONI observation of the planet β Pictoris b. We recovered the CO and H2O detections in the atmosphere of β Pic b by using molecular mapping. We further determined some basic properties of its atmosphere, with Teq=1748−4+3 K, sub-solar [Fe/H]=− 0.235−0.013+0.015 dex, and solar C/O=0.551 ±0.002. These results are in contrast to values measured for the same exoplanet with other infrared instruments. We confirmed a low projected equatorial velocity of 25−6+5 km s−1. We were also able to measure, for the first time and with a medium-resolution spectrograph, the radial velocity of β Pic b relative to the central star at MJD=56910.38 with a km s−1 precision of −11.3±1.1 km s−1. This result is compatible with the ephemerides, based on the current knowledge of the β Pic system. [ABSTRACT FROM AUTHOR]

Context. Using emission lines from metals, we investigate the three-dimensional distribution of temperature and chemistry in ultra-hot Jupiters. Aims. Existing observations of WASP-121 b have suggested an underabundance of titanium and titanium oxide in its terminator region. In this study, we aim to determine whether this depletion is global by investigating the dayside emission spectrum. Methods. We analyzed eight epochs of high-resolution spectra obtained with the ESPRESSO spectrograph, targeting orbital phases when the dayside is in view. We used a cross-correlation method to search for various atoms, TiO, and VO, and compare the results to models. We constrained the velocities and phase function of the emission signal using a Bayesian framework. Results. We report significant detections of Ca I, V I, Cr I, Mn I, Fe I, Co I, and Ni I, but not Ti or TiO. Models containing titanium are unable to reproduce the data. The detected signals are consistent with the known orbital and systemic velocities and with peak emission originating from the substellar point. Conclusions. We find that titanium is depleted from regions of the atmosphere where transmission and emission spectroscopy are sensitive. Supported by recent HST observations of the nightside, we interpret this as evidence for the nightside condensation of titanium, which prevents it from being mixed back into the upper layers of the atmosphere elsewhere on the planet. Species with lower condensation temperatures are unaffected, implying that sharp chemical transitions exist between ultra-hot Jupiters that have slight differences in temperature or dynamical properties. As TiO can act as a strong source of stratospheric heating, cold-trapping creates a coupling between the thermal structures on the dayside and nightside, and thus condensation chemistry needs to be included in global circulation models. Observed elemental abundances in hot Jupiters will not reliably be representative of bulk abundances unless nightside condensation is robustly accounted for or the planet is hot enough to avoid nightside cold traps entirely. Secondary eclipse observations by JWST/NIRISS have the potential to confirm an absence of TiO bands at red-optical wavelengths. We also find that the abundance ratios of metal oxides to their atomic metals (e.g., TiO/Ti) depend strongly on the atmospheric C/O ratio, and that planetary rotation may significantly lower the apparent orbital velocity of the emission signal. [ABSTRACT FROM AUTHOR]

Optical phase curves of hot Jupiters can reveal global scattering properties. We implemented a Bayesian inference framework for optical phase curves with flux contributions from: reflected light from a potentially inhomogeneous atmosphere, thermal emission, ellipsoidal variations, Doppler beaming, and stellar rotation via a Gaussian process in the time domain. We probed for atmospheric homogeneity and time variability using the reflected light inferences for highly precise Kepler light curves of five hot Jupiters. We also investigated the scattering properties that constrain the most likely condensates in the inhomogeneous atmospheres. Cross validation prefers inhomogeneous albedo distributions for Kepler-7 b and Kepler-41 b, and a weak preference for inhomogeneity for KOI-13 b. None of the five planets exhibit significant variations in geometric albedo on 1-yr timescales, in agreement with theoretical expectations. We show that analytic reflected light phase curves with isotropic multiple scattering are in excellent agreement with full Rayleigh multiple scattering calculations, allowing for accelerated and analytic inference. In a case study of Kepler-41 b, we identified perovskite, forsterite, and enstatite as possible scattering species consistent with the reflected light phase curves, with condensate particle radii in the range 0.01–0.1 µm. [ABSTRACT FROM AUTHOR]