Planetary systems

arXiv:2606.18338v3 Announce Type: replace-cross Abstract: The search for life beyond Earth will depend on detecting faint signatures in the atmospheres of potentially habitable exoplanets. Interpreting those signatures requires understanding the host planet's climate: the same molecule may signal life on one planet and abiotic chemistry on another. Global climate models (GCMs) provide this understanding, but individual runs can require up to millions of core-hours and substantial domain expert time. Machine-learning emulators could remove this bottleneck, but progress has been limited by the absence of a curated, multi-model exoclimate dataset. We introduce ThousandWorlds, an ML-ready benchmark for exoclimate emulation and for the broader regime of low-data, multi-simulator, parameter-to-field regression. The dataset contains approximately 1,700 simulations from five GCMs, mapping eight planet parameters to 3D atmospheric fields including temperature, humidity, winds, clouds, and radiation. Three nested subsets define progressively harder challenges: single-simulator regression, multi-simulator regression with complete observations, and multi-simulator regression with structured missingness. We propose two evaluation protocols: one for ranking methods, and one that measures performance relative to the disagreement between GCMs themselves. We evaluate ten baselines spanning simple methods, trees, deep learning, and Gaussian processes. GP-based methods perform best, suggesting that ThousandWorlds exposes a regime where off-the-shelf deep learning does not yet succeed. Data: https://doi.org/10.57967/hf/8695. Code: https://github.com/edstevenson/ThousandWorlds.

arXiv:2609.23091v1 Announce Type: new Abstract: Super-Earth exoplanets are among the most abundant planets known, yet their bulk densities leave the interior state degenerate. The static structure models used to interpret them, and the interior retrievals built on them, typically describe the cold, solidified end state of an evolution that begins hot and molten. During this magma ocean stage the interior, the outgassed atmosphere, and the surface co-evolve and set the long-term climate and geophysics of super-Earths. We develop and validate a fully coupled model for the structural and thermal evolution of super-Earth exoplanets within the PROTEUS framework, including new and upgraded models of the interior structure, mantle energetics, and volatile outgassing. In volatile-poor super-Earths of 1 to 10 Earth masses, the silicate interior contracts by about 10 % of its molten radius through cooling and crystallisation, nearly independent of planet mass and driven by the thinning silicate shell alone. The solidified radius is set by planetary mass and core fraction, insensitive to the host star, irradiation, and initial thermal state. In contrast, volatile-rich super-Earths at and above about 5 Earth masses may not solidify: their thick outgassed atmospheres throttle the surface heat loss until the interior settles into a deep magma ocean, keeping the planet inflated and limiting the contraction to about half its volatile-poor value. Mantle contraction alone thus shapes the low-mass exoplanet transit population, motivating joint interpretation of atmospheric and geophysical signatures in upcoming exoplanet surveys.

arXiv:2609.17505v1 Announce Type: new Abstract: Measuring M dwarf ages is a central challenge in stellar astrophysics. These stars evolve so slowly that isochrone fitting gives little constraint, requiring alternative methods based on rotation, activity, and kinematics. Reliable ages help constrain the formation and evolution of planetary systems around M dwarfs, including the temperate sub-Neptunes now being characterised with the James Webb Space Telescope (JWST). We present an age analysis of six nearby M dwarf planet hosts (TOI-732, TOI-736, TOI-270, TOI-1468, TOI-1231, and K2-18) using lithium absorption at 6708 \AA, rotation periods, and Galactic kinematics. The Li I 6708 \AA feature is absent above 3$\sigma$ in all targets, implying substantial depletion and ages exceeding 200 Myr. Rotation periods of 39-145 days yield ages of 2.8-8.6 Gyr, calibrated against open cluster M dwarfs and including the intrinsic dispersion of the rotation-age relation. Kinematic ages span 0.8-13 Gyr with uncertainties of 4-6 Gyr. These are less precise per star but help identify outliers such as TOI-1231 (~13 Gyr) and K2-18 ( ~1-2 Gyr) and place the stars in Galactic context. Rotation yields age constraints 2-6 times tighter than kinematics where periods are measured, and comparable constraints where periods must be inferred from chromospheric activity. Combining multiple indicators enables more secure classification of these stars' evolutionary states, providing reference points for future comparative studies.

arXiv:2609.11798v1 Announce Type: new Abstract: Binary stars are common in the Galaxy, and understanding how stellar binarity influences the formation and evolution of planetary systems is an active area of research. In this study, we use metal-enriched white dwarfs in wide binaries as tracers of long-lived planetary systems. With Data Release 1 from the Dark Energy Spectroscopic Instrument (DESI), we find that the fraction of cool metal-enriched white dwarfs in wide binaries is 9.8\,$\pm$\,2.1\%, significantly lower (4.7\,$\sigma$) than the 20.5\,$\pm$\,0.9\% in a control sample of single systems. Furthermore, we identify a tentative dependence of metal enrichment on projected separation and white dwarf effective temperature, where enrichment fraction decreases at smaller separations and lower temperatures. These findings indicate that, compared to single stars, binary systems either start with smaller initial planetary reservoirs due to suppressed planetesimal formation or undergo more rapid depletion of planetary material during the initial part of the white dwarf stage.

arXiv:2609.05366v1 Announce Type: new Abstract: Hints of planet formation have been independently reported within the gap of the disc around 2MASS J16120668-301027 from millimetre continuum, infrared, and H-alpha observations. In this work, we present new evidence for ongoing planet formation based on Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 observations, detecting 0.87 mm dust continuum emission together with 12CO (J=3-2) and 13CO (J=3-2) line emission. Visibility modelling of the continuum data reveals an inner disc and two dust rings peaking at 23 and 75 au. The continuum morphology is better reproduced by an eccentric disc model (e approximately 0.1) than by an axisymmetric disc. We further investigate the gas kinematics through modelling of the 12CO channel maps. The residual line-width map shows a localised increase in velocity dispersion at the position of a previously reported circumplanetary disc candidate (deprojected radius approximately 32 au, position angle approximately 170 degrees) and along its orbit. This signal is spatially coincident with kink-like features and a transition from sub-Keplerian to super-Keplerian velocities. In addition, the velocity residual map exhibits an arc-like structure extending outward from the planet candidate, while the gas kinematics, despite substantial uncertainties, is consistent with inflow towards the candidate's orbital radius. The observed increase in velocity dispersion agrees with predictions from planet-disc interaction simulations, which produce enhanced turbulence both at the planet location and along its orbital path. Taken together, the continuum morphology and gas kinematic signatures provide compelling new evidence for ongoing planet formation within the disc gap.

arXiv:2609.05264v1 Announce Type: new Abstract: The launch of JWST has enabled unprecedented atmospheric characterization of exoplanets. In particular, the JWST-MIRI instrument in the mid-infrared enables probing of molecular species that are harder to detect in the near-infrared. This has come to the fore with the first MIRI-LRS observation of a candidate hycean world, K2-18 b, with potential signs of dimethyl sulfide in its atmosphere. The statistical significance of this result has been debated in subsequent works, arguing instead for the possibility of random noise, instrumental systematics, or a different molecule. The same applies to similar spectra reported for several other exoplanets using MIRI-LRS and interpreted with similar retrieval architectures. In this work, we distinguish between these possibilities with a homogeneous survey of MIRI-LRS transmission spectra of 10 diverse exoplanets, from temperate sub-Neptunes to hot rocky planets and gas giants. We first perform a comparative assessment of the spectra, considering fits with featureless models and pairwise correlations, followed by extensive atmospheric retrievals. With the retrievals, we search for over 150 trace species in the atmosphere of each planet. We find hints of complex molecules in the temperate sub-Neptunes and candidate hycean worlds K2-18 b, TOI-732 c and TOI-270 d, similar to previous works, but not in the other seven planets. Our results indicate that the observed spectral features are likely due to molecular absorption rather than instrument systematics or noise, and underscore these temperate sub-Neptunes as a unique class of planets. More observations are required to robustly identify the specific molecules and constrain the underlying chemical processes, biotic or abiotic.

arXiv:2609.03144v1 Announce Type: new Abstract: Rocky planets evolve through the exchange of volatiles between their interiors and atmospheres, an interplay still poorly constrained by observations. Remarkably, highly irradiated ultrashort-period (USP) exoplanets may offer a window into this exchange -- some retain low bulk densities compatible with volatile-rich envelopes surrounding rocky interiors, indicating possible secondary atmospheres. TOI-561 b is a prime example, with a bulk density of $4.3\pm0.4$ g cm$^{-3}$ and recent JWST observations favoring a thick volatile atmosphere overlying a dayside magma ocean. Here, we investigate the evolutionary pathways allowing TOI-561 b to retain a substantial atmosphere over gigayears using the PROTEUS coupled interior--atmosphere framework. We explore different core radius fractions, Bond albedos, atmospheric escape efficiencies, mantle redox states, and initial C--H--O--N--S volatile inventories, under in situ evolution and late inward migration. Over half of our simulations leave a bare interior too dense to match observations. Successful cases favor a volatile-rich origin ($\lesssim200$ Earth oceans of hydrogen, S/H $\le10$, and N/H $\le1$), an oxidized mantle ($f$O$_2 \gtrsim \mathrm{IW}+4$), a small iron core ($\le 0.40$ for the core radius fraction), and low escape efficiency ($\epsilon \lesssim 10^{-3}$) in the hydrodynamic escape regime. At present, TOI-561 b is consistent with a global magma ocean beneath a thick (surface pressure $\approx 10^{3}$--$10^{4}$ bar), high mean molecular weight atmosphere ($38$--$60$ g mol$^{-1}$). Two archetypes emerge, differentiated by bulk sulfur content: a CO$_2$-dominated and an SO$_2$-dominated atmosphere. Migration is viable but not required to reproduce the observations. Our study illustrates how interior--atmosphere coupling governs atmospheric retention on irradiated rocky planets.

arXiv:2608.21519v2 Announce Type: replace Abstract: Ultra-short period (USP) rocky planets are expected to be depleted of any substantial gaseous envelope due to the intense irradiation they receive from their host star, making the recent detection of an atmosphere around TOI-561~b particularly surprising. That finding was based on the planet's bulk density and dayside emission spectrum, but full-orbit phase curve observations offer a more comprehensive way to constrain the presence and characteristics of a planet's atmosphere. In this paper, we map TOI-561~b's 3-5~$\mu$m emission using JWST/NIRSpec multi-orbit spectroscopic phase curves, explicitly accounting for the curvature of the out-of-eclipse baseline and possible hotspot offsets. From a simple energy balance argument as well as comparing to general circulation models, we find the phase curve observations are best explained with high Bond albedo and moderate global heat transfer. Our 37-hour continuous observation provides a long baseline that allows us to model stellar granulation, the planetary phase curve, and dayside emission simultaneously, effectively disentangling these signals and yielding a dayside emission spectrum that is more robust against stellar variability and consistent with previous eclipse-only fits. Using general circulation model outputs, we constrain where clouds can plausibly form and test candidate compositions, finding that silicate clouds, such as SiO$_2$ and MgSiO$_3$, can form on the dayside near the terminator and explain the observed albedo. Our findings confirm that TOI-561~b appears to have a global reflective atmosphere, suggesting exchange of volatiles with the interior to maintain it.

arXiv:2608.21519v1 Announce Type: new Abstract: Ultra-short period (USP) rocky planets are expected to be depleted of any substantial gaseous envelope due to the intense irradiation they receive from their host star, making the recent detection of an atmosphere around TOI-561~b particularly surprising. That finding was based on the planet's bulk density and dayside emission spectrum, but full-orbit phase curve observations offer a more comprehensive way to constrain the presence and characteristics of a planet's atmosphere. In this paper, we map TOI-561~b's 3-5~$\mu$m emission using JWST/NIRSpec multi-orbit spectroscopic phase curves, explicitly accounting for the curvature of the out-of-eclipse baseline and possible hotspot offsets. From a simple energy balance argument as well as comparing to general circulation models, we find the phase curve observations are best explained with high Bond albedo and moderate global heat transfer. Our 37-hour continuous observation provides a long baseline that allows us to model stellar granulation, the planetary phase curve, and dayside emission simultaneously, effectively disentangling these signals and yielding a dayside emission spectrum that is more robust against stellar variability and consistent with previous eclipse-only fits. Using general circulation model outputs, we constrain where clouds can plausibly form and test candidate compositions, finding that silicate clouds, such as SiO$_2$ and MgSiO$_3$, can form on the dayside near the terminator and explain the observed albedo. Our findings confirm that TOI-561~b appears to have a global reflective atmosphere, suggesting exchange of volatiles with the interior to maintain it.

arXiv:2608.06583v1 Announce Type: new Abstract: JWST defines a new era for the data-driven approach of retrieval modelling, which has become a cornerstone tool for the statistical inference of exoplanetary and brown dwarf properties. The Early Release Science program #1386 observations of VHS 1256 b represent a huge jump in data quality, data quantity and spectral coverage for such objects. VHS 1256 b is a young, planetary mass and extremely variable companion that populates the enigmatic L/T cohort of substellar atmospheres. In this first retrieval analysis of the full 1 - 18 micron dataset, we apply the Brewster retrieval framework to the NIRSpec and MIRI spectroscopic observations of VHS 1256 b, exploring a variety of cloud species and structures. Using Delta(BIC) we find that the data is best described by a forsterite (Mg$_{2}$SiO$_{4}$) and enstatite (MgSiO$_{3}$) cloud combination. Our analysis shows a strong preference for patchy silicate cloud coverage, which aligns with VHS 1256 b's extensive and well documented spectral variability. Our retrieval is able to place constraints on the abundances of H$_{2}$O, CO, CO$_{2}$, CH$_{4}$ as well as NH$_{3}$. We also show that the retrieved parameters are sensitive to the data used and the relative signal-to-noise ratios between data from different instruments. We conclude with the next steps for the wider retrieval community to better understand young and cloudy exoplanetary atmospheres.

arXiv:2606.26381v2 Announce Type: replace Abstract: The PDS 70 cavity hosts two confirmed directly imaged protoplanets and a third inner planet candidate at 13au, labeled PDS 70 d. Despite its Keplerian motion, its unusually blue spectrum challenges a planetary interpretation. We further investigate the presence and nature of a third inner planet using new SPHERE and GRAVITY+ observations. Using the star-hopping strategy, we obtained coronagraphic IRDIS polarimetric observations in the H-band, and non-coronagraphic observations with IRDIFS in the YJHK-bands. We also searched for a planetary signal with GRAVITY in the 4UT configuration. We consistently detect two elongated inner emissions with SPHERE: the previously proposed planet candidate and another feature that appears to share the same orbit while leading it by ~120$^\circ$. Both features show dust-scattered-light spectra but different colors, possibly indicating different grain sizes. Such configuration is consistent with co-orbital dust accumulated at the stable Lagrangian regions of a distinct and yet undetected planet. GRAVITY yields a marginal (3$\sigma$) detection at the predicted location along the same orbit ($\rho=76.2\pm0.29$mas, PA=$226.50\pm0.21^\circ$), and consistent with a ~3$M_{\rm Jup}$ planet. This planet-like signal is aligned with a narrow shadow that we detect in the outer disk. We also detect polarized emission very close to the star likely arising from the inner disk. The apparent embedding of the two dust clumps within it motivates an inner-disk origin as an alternative scenario. We conclude that the previously reported third planet candidate traces a dust clump either trailing an unseen planet on the same orbit or a rotating substructure within the inner disk. Further observations are needed to test these scenarios. Confirming the new GRAVITY planet-like signal would support co-orbital substructures as indirect tracers of protoplanets.

arXiv:2604.15891v2 Announce Type: replace Abstract: Static structure models, which map mass-radius constraints to bulk planet composition, are frequently used to categorise exoplanets due to their computational efficiency and the high-level insight they offer into planetary properties. However, static structure models typically have simplified atmospheric treatments, which may introduce systematic biases when interpreting the structures - and therefore the climates - of sub-Neptunes and super-Earths. We present a framework for recovering exoplanet properties using static structure models that accounts for necessary physical-chemical complexity in their atmospheres. We produce a comprehensive library of 504,000 exoplanet simulations that unify deep planetary interior structure with radiative-convective-chemical climate calculations. From these models we demonstrate that a planet's envelope mass fraction - a critical parameter to infer - is frequently degenerate with its instellation flux and atmospheric metallicity, and sensitive to the treatment of gravitational acceleration at the mbar level. Such uncertainties have significant implications for inferring planetary processes, as our modelling shows that habitable-zone sub-Neptunes readily host supercritical surfaces or deep magma oceans, despite their temperate irradiation regime. To marginalise over these uncertainties, we introduce a Bayesian retrieval tool that uses our library of self-consistent models. By applying this Bayesian approach to case-studies of pi Men c and TOI-421 b, we show that robust physical interpretations are achievable through whole-planet mass-radius retrievals. While new data from JWST, Ariel, and PLATO will expand our observational horizon, physically-consistent modelling provides the means to transition from categorical interpretations toward a comprehensive picture of the exoplanet continuum.

arXiv:2607.23741v2 Announce Type: replace Abstract: Context. A significant fraction (>30%) of planet-forming disks and planetary are misaligned with respect to the rotational axis of their host stars, yet the dominant mechanism responsible for these misalignments remains unclear. Aims. We aim to observationally constrain the angular momentum of Class II protoplanetary disks and assess whether late-stage infall of material can bring sufficient angular momentum to tilt them. Methods. We first computed the angular momenta of 15 disks with surface density profiles inferred from dynamical modeling of high angular resolution ALMA observations. Based on this sample, we derived a relation linking disk angular momentum to stellar mass, disk mass, and the radius enclosing 90% of the 13CO flux and used it to estimate angular momenta of 18 more disks. We then compared disk values with theoretical predictions for late-stage accretion from clouds and observed streamers. Results. Angular momentum for most disks is lower than what theoretical models predict for late infall. This is also in qualitative agreement with comparison with streamer observations, however, characterization of mass of reservoirs feeding the streamers is needed to confirm this picture. Conclusions. Interactions with nearby clouds, resulting in late-stage infall of material onto Class II disks, can potentially explain the observed misalignments within disks and planetary systems.

arXiv:2607.23741v1 Announce Type: new Abstract: Context. A significant fraction (>30%) of planet-forming disks and planetary are misaligned with respect to the rotational axis of their host stars, yet the dominant mechanism responsible for these misalignments remains unclear. Aims. We aim to observationally constrain the angular momentum of Class II protoplanetary disks and assess whether late-stage infall of material can bring sufficient angular momentum to tilt them. Methods. We first computed the angular momenta of 15 disks with surface density profiles inferred from dynamical modeling of high angular resolution ALMA observations. Based on this sample, we derived a relation linking disk angular momentum to stellar mass, disk mass, and the radius enclosing 90% of the 13CO flux and used it to estimate angular momenta of 18 more disks. We then compared disk values with theoretical predictions for late-stage accretion from clouds and observed streamers. Results. Angular momentum for most disks is lower than what theoretical models predict for late infall. This is also in qualitative agreement with comparison with streamer observations, however, characterization of mass of reservoirs feeding the streamers is needed to confirm this picture. Conclusions. Interactions with nearby clouds, resulting in late-stage infall of material onto Class II disks, can potentially explain the observed misalignments within disks and planetary systems.

arXiv:2607.22911v1 Announce Type: new Abstract: White dwarf (WD) atmospheric metal pollution provides strong evidence for the presence of remnant planetary material and it can be used as an indirect tracer of outer planetary systems. We analyze whether the presence of a wide stellar companion affects the occurrence of outer planetary systems by comparing the incidence of calcium (Ca) pollution in hydrogen-atmosphere WDs in wide binaries and in apparently single stars. We construct two sample pairs: a large homogeneous SDSS low-resolution spectroscopic set and a smaller high-resolution sample. For each WD, we measure Ca abundances or upper limits and compute detectability-corrected cumulative pollution fractions that account for variations in effective temperature, signal-to-noise ratio, and spectral resolution. In the SDSS-based samples, we find pollution fractions <1%, defined as the fraction of WDs with detected Ca, for both single WDs and WDs in wide binaries. After correcting for detectability, the cumulative abundance distributions of the two populations are statistically consistent. The same conclusion is obtained for the higher-resolution samples, despite their different raw detection fractions. Our results indicate no statistically significant difference in the occurrence rate of remnant outer planetary systems between single stars and stars with wide (~200 au) companions, within the current uncertainties. These uncertainties are significant because the samples contain only a small number of polluted WDs. The corrected detectability cumulative fraction approach used here provides a framework for comparing samples with different detection sensitivities and can be extended to larger spectroscopic datasets. Such samples will be required to determine whether wide stellar companions affect the survival and delivery of planetary material and to search for more subtle trends, for example, as a function of companion separation.

arXiv:2607.15011v1 Announce Type: new Abstract: The earliest rocky planet atmospheres are shaped by competition between initial volatile inventories and atmospheric escape. On young magma ocean planets, outgassing competes with atmospheric escape, controlling volatile retention and atmospheric evolution. We investigate how atmospheric escape and replenishment via outgassing during magma ocean crystallization shape rocky planet atmospheres. We extend a coupled interior-atmosphere model to simulate rocky planet evolution during the magma ocean era by incorporating an energy-limited atmospheric escape module. Comparing radiative-convective and prescribed-convective atmospheres, we quantify how atmospheric energy transport affects escape. We explore a wide range of orbital separations, escape efficiencies, oxidation states, and initial volatile inventories to identify regimes where sustained magma-ocean outgassing or escape dominates. We estimate atmospheric loss and compositions for young rocky planets around Sun-like and M-dwarf stars over geologic timescales. Atmospheric escape shortens magma ocean lifetimes by weakening greenhouse insulation. Radiative-convective atmospheres reduce solidification timescales compared to purely convective cases. Volatile dissolution into the magma ocean interacts with escape to chemically fractionate the planetary volatile budget over time by retaining more soluble species. For Earth-mass planets, atmospheres survive if loss rates remain moderate. Mantle redox state remains a key control on retained atmospheric composition: high oxygen fugacity (fO2) yields heavier, H2O- and CO2-rich atmospheres, while low fO2 produces light, H2- or CO-dominated atmospheres, consistent with previous studies. Orbital separation, initial volatile inventory, and stellar type produce diverse evolutionary pathways, from bare rocky planets to magma oceans with thick atmospheres, ranging from H2- to SO2-dominated.

arXiv:2607.14251v1 Announce Type: new Abstract: Metal-enriched white dwarfs provide a unique insight into the composition of exoplanet interiors. These stars accrete the debris of disrupted planetary bodies, and hence, measuring the stellar parameters and photospheric abundances yields the bulk compositions of the parent bodies. At present, over 1750 debris-accreting white dwarfs are known, but just a few dozen are sufficiently enriched to allow a detailed abundance study. Here we report the analysis of 12 highly metal-enriched white dwarfs observed within the Data Release~1 of the Dark Energy Spectroscopic Instrument (DESI). We characterised their stellar parameters and photospheric metal abundances and we identified between three and ten different elements in their optical spectra, including most of the rock-forming species: O, Mg, Si, Ca and Fe. We conclude that the accreted bodies broadly resemble compositions found within the inner Solar System such as primitive meteorites, processed material or planetary cores. Six of the systems allowed a more thorough analysis: four of the parent bodies are composed of dry rock-forming elements; and two of them of something akin to a water-rich planetesimal. Thus, this study establishes DESI as a potent survey for identifying metal-rich targets, yielding reliable compositions of accreted exoplanetary material.

arXiv:2607.15204v1 Announce Type: new Abstract: Volatile outgassing from planetary interiors controls the composition of rocky exoplanets' secondary atmospheres. However, observations indicate that disequilibrium processes, such as photochemistry and vertical transport, can strongly alter the chemical structure of Hot Jupiters. Which process dominates under different types of rocky planets, and how outgassing and photochemistry jointly determine the atmospheric composition, remain open questions. Sulfur species are promising tracers of interior-atmosphere coupling because their atmospheric abundances are sensitive to both mantle redox state and stellar irradiation. The PROTEUS planetary interior-atmosphere evolution modelling framework is coupled to two chemical models, FastChem and VULCAN, for post-processed chemistry calculations. We run a grid of planetary evolution simulations spanning diverse mantle redox states, instellation fluxes, and Solar versus M-star host-star spectra. For each case, we compare atmospheric compositions under thermochemical equilibrium, only vertical transport, and vertical transport plus photochemistry. The bulk atmospheric composition remains controlled by the redox state of the mantle and outgassing history, even when disequilibrium chemistry is included. Reduced mantles produce atmospheres rich in H2, and oxidised mantles are dominated by CO2. Photochemistry affects the upper atmosphere, strongly depleting neutral volatiles and enhancing radicals, especially for highly irradiated cases. SO2 is strongly enhanced at intermediate-to-oxidised redox states. Synthetic emission spectra show that photochemical SO2 can generate absorption features at 4 um and at 7.3 / 8.7 um, reaching ~60 ppm and ~100 ppm, before sequentially returning to the outgassed signatures of ~30 ppm and ~50 ppm for the oxidised mantle redox state. These signatures are detectable with JWST, motivating targeted observational campaigns.

arXiv:2607.13793v1 Announce Type: new Abstract: We demonstrate that the redox-sensitivity of mantle outgassing can trigger transient episodes of atmospheric re-inflation in highly irradiated and geochemically-reduced super-Earths, a mechanism we term reflation. Mantle redox governs the outgassing and speciation of CHONS volatiles, setting the background secondary atmospheric composition during extended photoevaporation at highly irradiated conditions. Using simulations of the coupled atmosphere-interior evolution of irradiated super-Earths, we illustrate that reduced mantles close to the iron-wustite buffer initially produce CO-dominated atmospheres. Hydrodynamic escape continuously removes volatiles while outgassing from the melt replenishes the atmosphere with H2, converted from H2O dissolved in the underlying magma ocean. This leads to a late-stage transition from C- to H-dominated gas that transiently re-inflates super-Earth atmospheres and decreases their bulk densities by up to $\sim$60$\%$ between several hundreds of Myr to Gyr after their formation, prior to complete atmospheric erosion by photoevaporation. In contrast, oxidised mantles, closer to Earth-like geochemistry, strongly buffer their atmospheric composition while exposed to hydrodynamic escape, producing monotonic radius deflation. Reflation events are triggered by geochemically-reduced mantles, intermediate escape efficiencies, high irradiation, and initial water inventories $\gtrsim$ 5 Earth oceans. This redox-dependent evolutionary divergence hinges on the sensitive feedback between interior and atmospheric evolution serving as a potential tracer of historical geochemical state. Population-level reflation signatures of close-in super-Earths may thus serve as tracers of interior geochemistry and formation conditions.

arXiv:2607.07182v1 Announce Type: new Abstract: The LTT3780 system hosts two known exoplanets-LTT3780b, a rocky super-Earth, and LTT3780c, a temperate sub-Neptune-orbiting a nearby M dwarf on opposite sides of the radius valley. LTT3780c has been proposed as a candidate Hycean world, making the system an important target for astrobiological investigation, particularly in light of recent JWST atmospheric observations. Although biosignature and technosignature searches both seek evidence of life beyond Earth, these approaches have historically been pursued independently. Well-characterized exoplanet systems provide an opportunity to combine these complementary search strategies. In this work, we conducted radio technosignature observations of the LTT3780 system using both the Allen Telescope Array (ATA) and the Karl G. Jansky Very Large Array (VLA). The two facilities provide complementary observational capabilities, with the ATA optimized for wide-band multi-beam post-processing analyses and the VLA enabling high-sensitivity real-time interferometric searches. Across approx 30 hr of total observing time, we searched for narrowband Doppler-drifting signals in the frequency range approx 1--10 GHz. After applying comprehensive radio-frequency interference mitigation and multi-beam consistency tests, no candidate signals consistent with astrophysical or technosignature origins were identified. We place minimum detectable effective isotropic radiated power limits of 4.7 X 10^12--3.6 X 10^13W across the observed bands and facilities. Although no technosignatures were detected, this work demonstrates how complementary observation and analysis strategies can be applied to exoplanets of astrobiological interest and serves as a pathfinder for future combined biosignature and technosignature investigations.