![Top left: (pgas, Tgas) cross-section through the terminators of WASP-69 b, with the location of the CH4 quench point overlaid (light blue line). We define the CH4 quench level as the pressure where the absolute relative difference between the equilibrium and disequilibrium concentrations first exceeds 10−3. Top right: Column densities in the line-of-sight direction in the atmosphere of WASP-69 b for [M/H] = 1.0, and C/O = 0.55 for CH44. Bottom: The same as for CH4 but now for SO2 (left) and CO2 (right). The terminator pressure scale is used as a radius axis. The hotspot offset at 10−4 bars is reflected in the column density of SO2, with larger concentrations being formed on the evening terminator. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Chemical-Tracers.png?resize=1200%2C716&ssl=1)
[astro-ph.EP] Warm giant exoplanets exhibit strong three-dimensional temperature contrasts that can significantly alter atmospheric chemistry through quenching and photochemistry, yet transmission spectra are commonly interpreted using one-dimensional, limb-averaged models. Such […]
astro-ph.EP
Posted inVenus
Altered Cosmic Organics As Venus’ Ultraviolet Absorbers
[astro-ph.EP] Venus’ ultraviolet (UV) absorbers significantly contribute to the atmosphere’s energy budget. However, the composition of these absorbers remains a mystery.
![(a) Schematic of Europan ice-ocean system [related image in 11]. (b) Map of sea surface temperature (◦C) showing the transition between the temperature-stratified North Atlantic Ocean and the salt-stratified Arctic Ocean; (c) Potential temperature (left) and salinity (right) profiles with depth from location near the North Pole. Different water-mass characteristics are labeled. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/What-can.png?resize=1200%2C582&ssl=1)
Posted inWater/Hycean Worlds & Oceanography
What Can Planetary Ice Shells Teach Us about Ocean Mixing and Life, and Why Salt Matters
[astro-ph.EP] Past and present climates, both on Earth and in planetary systems, maintain ice covers with underlying oceans. This can range from sea ice in the Arctic Ocean to global […]
Posted inExoplanets, -moons, -comets
Atmospheric Diversity of Giant Planet Analogs from 3-5µm with SPHEREx
[astro-ph.EP]. The emergent spectra of giant planets peak at thermal infrared wavelengths (3-5um) and possess atmospheric features in this regime that trace carbon chemistry, vertical mixing, clouds, and composition.
Posted inAstrogeology
Setting The Stage: The Early History Of The Solar System
[astro-ph.EP] This article reviews the early history of our solar system from an astrobiological perspective and presents evidence from meteorites and astronomical observations. The purpose is to trace the formation […]
![Benchmark test between chemcat (dashed black lines) and GGchem (solid colored lines) for a network of neutral species at 1 bar and temperatures from 100–6000 K (only selected species are shown). Both codes produced results typically consistent within 0.1 dex, with noticeable differences resulting from missing thermochemical data or at the lowest temperatures T ≲ 200 K. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Pyrat-Bay.png?resize=1200%2C713&ssl=1)
Posted inExoplanets, -moons, -comets
Pyrat Bay 2.0: An Upgraded Framework for Exoplanet Atmosphere Modeling in the JWST Era
[astro-ph.EP] This article presents a major update to the open-source Pyrat Bay modeling framework (version 2.0), tailored for the characterization of exoplanet atmospheres with the observational capabilities of current facilities, […]
![Illustration of the VHS 1256 b data used in this study. (Top) Full ERS #1386 program (V2) spectrum of VHS 1256 b with overlapping wavelengths between orders shown in grey. With 12 spectral orders populating the NIRSpec and MIRI data combination we have 11 overlaps present across the global spectrum. (Middle) NIRSpec data at its native resolution and the binned spectrum used in our retrieval analysis. (Bottom) MIRI data at its native resolution and the binned spectrum used in our retrieval analysis. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-JWST.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems VIII: Patchy Forsterite and Enstatite Clouds in the Atmosphere of VHS 1256 b.
[astro-ph.EP] 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.
![Illustration of the TRAPPIST-1 system and the most recent JWST constraints on planetary atmospheres. Planet size and distance roughly to scale. - [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/veiled.png?resize=1200%2C820&ssl=1)
Posted inTRAPPIST-1
Veiled in Starlight: Impacts of Stellar Contamination On Retrievals of TRAPPIST-1f’s Atmospheric Composition
[astro-ph.EP] The TRAPPIST-1 system offers seven terrestrial exoplanets with tight orbits and large radii ratios to the host star. If an atmosphere exists, transmission spectroscopy can be used to detect […]
![Inclination vs. semimajor axis for the NEOs. The main asteroid families that have been linked to ordinary chondrites are represented by gray squares. The ν6 secular resonance with Saturn and the 3:1 and 5:2 mean motion resonances with Jupiter are represented with dashed lines. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Size-Constraints.png?resize=1200%2C718&ssl=1)
Posted inAstrogeology
Size Constraints For The Pre-atmospheric Parent Bodies Of Ordinary Chondrites
[astro-ph.EP] The study of S-complex near-Earth objects (NEOs), the parent bodies of ordinary chondrites, has shown that they are dominated by asteroids with LL chondrite-like compositions. This is surprising because […]
![The mass-radius-period parameter spaces for short-period exoplanets. In (a), the radii and orbital periods of known planets are shown with systems coloured by the stellar effective temperature. The TASSIE II TOIs are highlighted as points with 3σ error bars for their radii. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-TASSIE-Program.png?resize=1200%2C719&ssl=1)
Posted inExoplanets, -moons, -comets
The TASSIE Program. II: Three Close-In Companions Orbiting Sun-Like Stars
[astro-ph.EP] We present three southern transiting giant planet candidates alerted by the Transiting Exoplanet Survey Satellite (TESS) mission and investigated at the University of Tasmania Greenhill Observatory (UTGO).