![Evolution of impact-generated debris for the high-velocity impact cases. Rows correspond to different impact scenarios with varying orbital periods (Porb) and impact velocities (vimp), as labeled. Columns show snapshots at 0.35, 2.65, 14.69, and 18.05 hr after impact. Particles are shown in a midplane slice with |z| < 0.1 R⊕, and colors indicate material origin and composition. In the 2.65 and 14.69 hr snapshots, particles are additionally highlighted according to their final fate, identifying those incorporated into the disk and those that later escaped from the system.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/A-Formation.png?resize=1200%2C716&ssl=1)
[astro-ph.EP] Massive moons around rocky exoplanets are expected outcomes of giant impacts, yet no exomoon has been securely confirmed.
astro-ph.EP
![Vertical cut through the best-fit disk model on a logarithmic radial scale. Shown are temperatures, where the gas density, ϱdisk, exceeds an assumed ISM density of ϱISM = 2.7 × 10−24 g cm−3 (Ferrière 2001) by a factor of 1000. The snowline at Tsnow = 170 K and the 100 K-line, as well as the unity optical depth lines at a wavelength of 3.1 µm (computed for the best-fit model described in Sect. 5.2.2) measured from the star to the observer and from observer to the star, illustrate the temperature and dust density structure of the disk. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Spatial.png?resize=1200%2C715&ssl=1)
Posted inAstrochemistry
Spatial Distribution Of Water Ice In The Protoplanetary Silhouette Disk d216-0939
[astro-ph.EP] The composition of rocky planets depends on the dust in their natal protoplanetary disk (PPD), potentially containing water ice. Crystalline water ice was detected in the PPD d216-0939 in […]
![[LEFT]: Schematic of the star–planet–observer geometry defining the phase angle α, measured between the star–planet and planet–observer directions. The hemisphere of the planet facing the star is fully illuminated (gold) at all times, while the opposite hemisphere remains in shadow. The observer sees only the portion of the illuminated hemisphere that is visible at a given α, with full illumination visible only at α = 0◦. [RIGHT]: Illustration of planetary phases along an edge-on orbit, with the star at the center and the observer direction indicated below the orbit. Although the star-facing hemisphere remains illuminated throughout the orbit, the visible fraction of this hemisphere changes with phase angle. Full phase occurs at α = 0◦, quadrature at α = 90◦, and new phase at α = 180 , with gibbous and crescent phases spanning the intermediate ranges. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/The-Impact.png?resize=1200%2C714&ssl=1)
Posted inAstronomy & Telescopes
The Impact of Planetary Phase Functions On Exo-Earth Detectability With EXOSIMS
[astro-ph.EP] The under-development NASA Habitable Worlds Observatory (HWO) aims to provide breakthroughs in exoplanet science, yet the most effective approaches to modeling the detection and characterization of potentially Earth-like worlds […]
![Proposed reaction network for the radiolysis of PCN:N2 ice by 40 MeV 40Ar9+ ions at 10 K. The scheme summarizes the main fragmentation, radical recombination, isomerization, and nitrogen incorporation pathways inferred from the infrared identifications and kinetic analysis. The radicals shown in the "Primary fragmentation" box are representative examples of how reactive intermediates are inferred from the experimental results and do not constitute an exhaustive list of all fragments produced during irradiation. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Formation.png?resize=1200%2C706&ssl=1)
Posted inAstrochemistry
Formation Of Nitriles And Isonitriles By The Heavy-ion Irradiation Of Propionitrile In N2-rich Astrophysical Ices
[astro-ph.EP] Context. Nitriles are key nitrogen-bearing organic molecules in dense clouds, star-forming regions, and nitrogen-rich icy environments. Understanding their stability and chemical evolution under energetic processing is essential for understanding […]
Posted inExoplanets, -moons, -comets
CHEOPS Photometry From 2024 Reveals A Reversal In The Transit-timing Variations Of AU Mic c
[astro-ph.EP]. We present new CHEOPS transit observations of AU Mic b and AU Mic c obtained between June and September 2024, extending the baseline of transit-timing measurements of this young […]
Posted inExoplanets, -moons, -comets
ESCAPE: A Small Explorer Mission To Study The Stellar Drivers Of Exoplanet Evolution
[astro-ph.EP] The long-term stability of exoplanetary atmospheres depends critically on the extreme-ultraviolet (EUV) photon and high-energy particle fluxes from the host star, which are poorly constrained.
Posted inComets and Asteroids
A JWST Study of Stardust. I. Infrared Spectroscopy of Comet 81P/Wild 2 and Overall Composition
[astro-ph.EP] We report observations of comet 81P/Wild 2, target of the Stardust sample return mission, on UT 2023 March 20 and 24 at a heliocentric distance (rH) of 1.85 au […]
![Retrieved emission spectra (blue regions) plotted with the true planet’s flux from our forward model (red) for each redox state considered (IW-6 to IW+6). The retrieved spectra denser region represents the 1𝜎 confidence level, intermediate region 2𝜎, thin region the 3𝜎 level. The observational noise from LIFEsim is shown as a gray envelope. The retrieved spectra capture most spectral features in observed planets, especially in the more pronounced oxidised cases (bottom row). -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/Characterizing-the.png?resize=1200%2C720&ssl=1)
Posted inExoplanets, -moons, -comets
Characterizing The Oxidation State Of Rocky Exoplanets With The Large Interferometer For Exoplanets (LIFE)
[astro-ph.EP] The oxidation state of rocky exoplanets is expected to play a fundamental role in shaping the chemical composition of their secondary atmospheres by influencing the chemical composition of volcanically […]
![Stellar influence on planetary habitability. Figure credit: solar images from NASA/ESA and KPNO/NSO/AURA/NSF, background pictures generated through OpenAI’s image-generation system (i.e., Adobe Firefly and ChatGPT Images 2.0). Illustration: K. Herbst - [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/StellarActivity.jpg?resize=1200%2C720&ssl=1)
Posted inHabitable Zones
Stellar Activity, Exoplanet, Habitability, Planetary Atmospheres
[astro-ph.EP] This chapter will review the deep connection of planetary habitability and stellar irradiation. We present the long-term stellar evolution as one of the drivers of atmospheric escape and climate […]
![Orbital trajectories of two example scattering experiments. Left: An interaction that results in a free-floating planet-moon pair. Right: An interaction that results in a free-floating planet and a separate free-floating moon. The starting points of the bodies are indicated by the black dots. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/07/Planet-moon.png?resize=1200%2C720&ssl=1)
Posted inStellar Cartography
Planet-moon Ejections In Close Stellar Encounters
[astro-ph.EP] Free-floating planet-moon pairs (FFPMs) may form when planetary systems experience close stellar encounters.