ALT Eclipse mapping is a well-established technique for constraining the spatial emission of hot Jupiter exoplanets. Brown dwarfs in ultra-short orbits around white dwarfs are an analog to hot Jupiters that can only ever be eclipsed within a limited range of latitudes. We adapt the eigenmapping method to disentangle the signals from the ever- and never-occulted regions. The result of this signal separation is a super-position of map structures, yielding sharp boundaries at the occultation region. We introduce a model that penalizes the harmonic complexity of the model map with Tikhonov regularization, whose parameters are tuned to reproduce the fit quality of the eigenmapping model. We use JWST NIRSpec/PRISM full-orbit observations of the eclipsing WD 1202-024 system as a template to construct and run injection-recovery tests on simulated light curves, isolating both latitudinal structures as well as emission from a physically-realistic general circulation model (GCM). In the latter, the n

ALT The small Solar System bodies (SSSBs) preserve records of the formation and evolution of the Solar System. In particular, the near-infrared wavelength region around 3 μm provides crucial insights into the origin and transport of hydrated materials and organics, although it is difficult to observe from the ground because of strong telluric absorption. We assess the observability of SSSBs as complementary science to the ESA Ariel space mission, operating in the visible to mid-infrared wavelength range (0.5–7.8 μm). Using the NASA JPL Horizons ephemeris system, we evaluate the visibility of known SSSBs from 2032 to 2035. Our analysis shows that Ariel can spectroscopically characterize up to 402 unique SSSBs under a conservative limiting visual magnitude of V=13.6. If observations can be extended to somewhat fainter targets (V=16), the number of observable SSSBs could increase to 2144. Assuming operational scenarios in which one SSSB is observed every 3, 7, or 30 days over a four-year miss

ALT Context. The DART impact might have substantially modified the surface and near-surface structure of Dimorphos, affecting the morphology and gravity field that is to be measured by ESA's Hera mission. Aims. We investigate the post-impact redistribution of ejecta and its dependence on the assumed internal structure of Dimorphos. Methods. We performed high-resolution SPH simulations of the DART impact into two low-cohesion rubble-pile models, with and without a large central boulder. We followed the processes of ejecta re-accumulation and gravity evolution for six hours. Results. The impact ejects about 13% of Dimorphos's mass, most of which is re-accreted, producing near-global resurfacing. The ejecta blanket exceeds 8 m around the impact depression but is only a few tens of centimetres thick near the antipode, with similar large-scale deposition in both interior models. Local gravity changes reach about 10% of the pre-impact value. The central boulder affects the surface gravity only w

ALT The diversity of planetary orbital architectures calls for observational constraints on radial variations in disk-plane orientation, or warps, yet such variations in dust disks remain poorly characterized. CQ Tau is a promising target because its misaligned inner disk and candidate gas warp suggest a radially extended warp. We present the ALMA 1.3 mm dust continuum image reconstructed from the real part of the visibilities, extracting the centro-symmetric disk structure. At an effective spatial resolution of 0.052” × 0.042” (7.8 × 6.3 au), the image reveals a bright main ring at radii of ∼20–70 au and an unresolved compact emission component tracing the inner disk around the central star. Ellipse fits centered on the stellar position to contours tracing the inner and outer edges of the ring reveal radial variations in position angles and inclinations. At the inner edge (∼21–26 au), the position angle and inclination span 214°–233° and 23°–39°, respectively, while they span 231°–235° an

ALT The knowledge of Titan's near-surface atmosphere is sparse. The Huygens descent probe measured winds, and the multiple dune field observations and possible dust storms suggest active near-surface dynamics. The Dragonfly rotorcraft lander will fly close to the surface in the Shangri-La region, near the Huygens landing site, where complex dune orientations were observed. This study presents the first mesoscale modelling of the near-surface dynamics in this region. However, due to a lack of high-resolution topography data, synthetic maps of surface properties were built. The surface was divided into different topographical units, such as plains, mountains, etc. The slopes and height of those units were then parametrised. Maps of thermal inertia, albedo and the aerodynamic roughness height were also built. The mesoscale model is coupled to a comprehensive radiative transfer code and forced by a global climate model. No moist processes are considered in this study. Topography has a major im

ALT In the outer regions of protoplanetary disks, dust grains are often mantled with a layer of ice containing simple molecules. The irradiation of the disk by far-ultraviolet (FUV) photons breaks such molecules, producing photoproducts (radicals, ions, and intermediary molecules) in the ice layer that can act as precursors to complex organics. As grains drift towards the warmer, inner region of the disk, their consequent sublimation of ices causes organic synthesis on their surfaces, potentially enhancing grain sticking and dust growth. In addition to interstellar medium radiation, FUV emission from the central star and nearby massive stars can contribute to photoproduct formation. We perform a vertical dust size evolution simulation including grain growth and fragmentation, and calculate photoproduct formation under irradiation from these three sources, treating the central star's FUV continuum and Lyman-α emission separately. We find that enhanced UV irradiation, particularly from stell

ALT A recent study reported a transiting giant-planet candidate with a mass of 9.4⁺⁴.⁹₋₄.₁ M_J and a radius of 1.7±0.1 R_J on a wide orbit around Boyajian's star (KIC 8462852, also called Tabby's star), which is well known for its irregular, deep flux dips. The reported radius is puzzling, because cool giant planets of ∼10 MJup are expected to have radii close to Jupiter's, so the companion appears ∼60–70% larger than standard models allow. Here we explore the solution that the planet is actually ringed. We develop a fast and accurate code to compute the transit light curve due to a ringed planet, and apply it to the TESS light curve. The ring model is marginally favoured by the data by Δχ²>10 and a difference in Bayesian information criterion (BIC) of <2. The preferred configuration is a Jupiter-sized (1.1 R_J) planet surrounded by an opaque, highly flattened ring extending to 3.1–4.4 planetary radii with a nearly polar obliquity. While the ring geometry is uncertain, simple estimates sug

ALT We present time-series observations of the long period comet C/2025 K1 (ATLAS) obtained in 2025-2026, bracketing the comet's fragmentation in early November 2025. We show that a simple radiation pressure model can explain many of the comet's properties: the rapid fading after fragmentation, the increasing mean particle size in the projected photometry aperture, and the time dependence of the surface brightness profile. Small dust particles (≲ 100 μm) dominate the coma, with average dust velocity ∼ a few × 1 meter s⁻¹. The nucleus radius is estimated at ∼0.5 km and the dust properties are consistent with, but do not prove, an origin in nucleus rotational breakup, followed by being swept down the tail by radiation pressure.

ALT Comet C/2025 K1 (ATLAS) underwent major fragmentation after its 2025 October 8 perihelion passage at q 0.33 au. We present four epochs of Johnson-Cousins BVR imaging obtained with the Mount Laguna Observatory 40-inch reflector on 2025 November 26, November 29, December 5, and December 8, sampling the subsequent evolution of the integrated fragment-coma complex. The images were homogenized to common circular two-dimensional effective point-spread functions before morphology was measured along the projected fragment axis. We evaluated 324 profile-extraction configurations and removed solutions whose localized peak landed on the search-window boundary. The fragment-axis surface-brightness enhancement relocates inward between November 26 and 29 and outward between December 5 and 8; the sign of both changes is recovered in every valid configuration and at all tested common target PSFs from 5.3 to 6.0 arcsec. Calibrated BVR photometry using Gaia DR3 synthetic Johnson-Kron-Cousins standards i

ALT The regular satellites of Jupiter and Saturn are substantially enriched in ice relative to the rock-rich solids of the outer Solar System. In addition, the satellites interior to Titan and distant Iapetus are icier than Titan itself. Collisional processes and subsequent migration can readily alter compositions deep in the planetary potential well, but producing a distant, ice-rich satellite with Iapetus's radius of about 700 km is a challenge. We show that differential ablation and capture of icy and rocky fragments from differentiated outer Solar System bodies can explain the bulk Jovian and Kronian satellite ice enrichment and supply the substantial ice-rich inventory needed for Iapetus. For 1 m–1 km fragments with the canonical size-distribution index p=3.5 and a source containing 30% ice by mass, the fixed radial distance Saturn calculation deposits material with ice fractions of 0.66 (delivery of vapor-only rock) or 0.50 (with retained rock melt) at 20 Saturn radii and nearly pure

ALT Rocky exoplanets orbiting M dwarf stars are often assumed to be synchronously rotating, such that water-trapping in ice sheets on the permanent nightside may pose a threat to habitability. However, in compact M dwarf systems, gravitational interactions between planets may cause the substellar point to librate or circulate on millennial timescales and sporadically change direction or speed. Here, we use a 3D global climate model to quantify, for the first time, the water-trapping capabilities of these "near"-synchronously rotating exoplanets, with TRAPPIST-1e as our test case. Across a range of synodic day lengths, we find that there is a permanent polar ice reservoir and an increasingly large build-up of lower-latitude transient nightside ice for longer days. A persistent ice-free region develops on the dayside where surface conditions can sustain liquid water. However, this steady-state ice distribution may never be realized since the accumulation timescale may be slower than changes

ALT Close-in gas giant atmospheres are in chemical disequilibrium. Solving 3D kinetics to capture one source of this disequilibrium, transport-induced quenching, is computationally demanding, so simplifications are used. General circulation models (GCMs) relax abundances on the timescale of a single conversion pathway. 1D models place a quench level and hold abundances vertically uniform above it. We test both simplifications on CH4 against aerosol-free, solar-composition GCM simulations with thermochemical kinetics for HAT-P-11b, HD 189733b, HD 209458b and WASP-17b. We find ten CH4-to-CO conversion pathways, varying with depth, longitude and planet. A single pathway controls CH4 quenching on the three cooler planets; on WASP-17b two compete. The CH4 quench level is 3D: where the atmosphere is hotter, or a faster pathway takes over, the conversion timescale shortens, the quench level rises and the quench-level abundance falls. On WASP-17b the pathway switch lifts the quench level over the

ALT Saturn's bulk metallicity and atmospheric volatile enrichments exceed those of Jupiter. Combined with their similar heavy-element masses, this suggests that Saturn formed farther out in a protoplanetary disk whose metallicity increased with heliocentric distance. Numerous models argue that Jupiter formed near the H₂O iceline; Saturn's composition is therefore expected to reflect accretion beyond this region. We test whether Saturn's elemental enrichments can be reproduced by formation near the CO₂ or CO icelines using a one-dimensional viscous α-disk model that tracks the transport, sublimation, and recondensation of 13 volatile carriers. We compute time-dependent radial distributions of solids and vapors for α=5×10⁻⁴–5×10⁻³ and varied CO/CO₂ abundance ratios, and compare the resulting metallicities and enrichments with Saturn's observed composition. Strong carbon and oxygen enrichment peaks result from the cold-finger effect, most prominently at the CO₂ iceline, where supersolar metal

ALT Around luminous A-type stars, retaining micrometer-sized dust grains is difficult owing to the high radiation pressure that repels particles with sizes below the blowout limit. Yet such particles have been evidenced in the terrestrial zone around those stars, via pronounced silicate spectral features. An in situ planetesimal belt that collisionally replenishes the dust is expected to deplete quickly, limiting the lifetime of observable features. However, modeling of such systems often relies on a power-law description of the grain size distribution that has a lower size limit owing to blowout. Using more complex, collisional simulations instead, we investigated the temporal evolution of hypothetical planetesimal belts in the terrestrial zone around five A-type stars showing strong spectral silicate features. A collisional cascade that is modified by radiation pressure results in dust distributions that replicate observed spectral features without requiring other physical processes. Whi

ALT Recent studies have shown the traditional comet brightening model, Hn, with a constant activity index n (i.e., single slope in log₁₀(rₕ)), fails to accurately describe heliocentric lightcurves at large distances, where water-ice sublimation is inefficient. We present a new empirical model, Hab, for distant comet brightening in which the effective brightening slope varies with heliocentric distance, rₕ. Using a multi-year pre-perihelion dataset from uniform instrumentation for 23 comets, we found that Hab provides the best match to long inbound arcs spanning a wide range in rₕ. The best-fit coefficients a and b cluster tightly for our best-observed comets, suggesting a common brightening behavior; we therefore also tested one- and two-parameter Hab variants in which a and/or b are fixed to anchor values derived from these comets (A₁ = 0.40 ± 0.09, B₁ = -1.78 ± 0.68), either individually, jointly, or via a linear relation. The three-parameter Hab model is strongly favored by the Bayesian

ALT As clock performance improves, the instability and uncertainty of the clock's fractional frequency shift (FFS) become comparable to the FFS caused by the lunar tidal response (LTR), so the influence of the LTR on lunar time needs to be investigated. In this paper, we used the Keplerian expansions method to study the FFS to the level of 10⁻¹⁸ caused by the LTR between two clocks placed in different positions on the Moon. We consider the case of the Moon orbiting in an elliptical orbit, which is closer to the actual situation compared to the case of the Moon moving in a circular orbit. An interesting phenomenon is found that the longitude difference between two clocks can cause a change in the amplitude and phase of the FFS due to the LTR, but the latitude difference only changes the amplitude of the FFS. We further estimated the clock difference between two clocks near the Moon caused by the LTR. When one clock is on the lunar surface, and the other is on the Earth's surface, the LTR wi

ALT We present 14 optical imaging and eight optical spectroscopic epochs of interstellar comet 3I/ATLAS from Keck/LRIS and Gemini/GMOS, two near-infrared (NIR) imaging epochs from Keck/MOSFIRE, and four NIR spectroscopic epochs from Gemini/Flamingos-2 and GNIRS, obtained between 2025 July and 2026 May. Mean GMOS colors of g-r=0.732±0.029, r-i=0.237±0.025, and i-z=0.109±0.022 mag show no significant change across perihelion. Phase-corrected red-band activity follows Afρ∝ rₕ⁻².¹⁰±⁰.¹⁴ inbound and rₕ⁻³.³⁴±⁰.⁴³ outbound. Transverse-width and sunward-plume speeds imply dust losses of 2.7×10⁹ and 1.0×10¹⁰ kg over 2025 July 3–2026 May 15 for 1-μm–1-mm grains, equivalent to global layers of 0.26 and 0.99 m under the adopted grain and nucleus assumptions. The concentrated coma, compact sunward feature, and antisolar tail seen on 2025 August 27 broadened by 2025 November 26; extended dust persisted through 2026 February 17. C₂/CN nearly doubled from 0.257±0.014 on 2025 September 14–15 to 0.481±0.080

ALT We introduce a Python package called exoVetter that produces vetting metrics and visualizations to evaluate transiting exoplanet signals found in high-cadence time-series photometry. exoVetter is open source, modular, and independent of the mission data so that it can be easily expanded and used as part of different transit search pipelines tuned to different science cases and missions. We demonstrate its use in a pipeline as a way to distinguish real events found in a box-least squares exoplanet transit search of 324,530 light curves from the Transiting Exoplanet Survey Satellite mission; we limit our demonstration to stars also observed by the more sensitive Kepler telescope as a way to establish ground truth for the events found in the light curves. Using this ground truth, we provide baseline thresholds for several flux-level vetters and one centroid-offset vetter when using exoVetter metrics on TESS data. Our demonstration also indicates that it is possible to create a planet cata

ALT Co-natal stars, wide binaries that form from the same molecular cloud, should harbor the same stellar composition. Observations indicate stellar abundance differences in a small fraction of these co-natal systems. The stellar abundance differences have been attributed to the ingestion of planets by their host stars. We analyze a previous sample of co-natal stars to determine the composition of the planets that were ingested. The abundance differences in these co-natal pairs can show a positive abundance difference of the refractory elements (Fe, Mg, Si) paired with a positive, zero, or negative abundance difference of volatiles (O, C, S). Positive trends of refractory and volatile abundance differences can be explained (at minimum) with the ingestion of a single planet by one of the stars. Positive trends of refractory abundance differences paired with zero or negative abundance differences of oxygen and carbon imply that both stars are required to ingest planets formed at different lo

ALT Atmospheric escape shapes close-in planets mostly in their first tens of Myr. The young V1298Tau system (10-30Myr) is a benchmark for investigating photoevaporation and planetary evolution at early stages. The metastable HeI near-infrared triplet is a key proxy for atmospheric escape. We aim to detect and characterise HeI in the extended atmosphere of V1298Taub. We analysed four transits over a 4-year baseline using GIARPS (GIANO-B + HARPS-N) at the Telescopio Nazionale Galileo. We re-derived the projected spin-orbit angle by modelling the Rossiter-McLaughlin effect. Using simultaneous optical and near-infrared high-resolution transmission spectroscopy of V1298Taub, we monitored the HeI triplet alongside key chromospheric indicators (log R'ₕₖ, Hα, and NaI) to disentangle stellar activity from planetary evaporation. While the stellar spectra show significant night-to-night variability, transmission spectroscopy reveals persistent HeI absorption across all four epochs. This contrasts wit