[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 […]
Comet
![Initial 𝑎c–𝑒c distribution of the 32,000 comets used in each end-to-end calculation. Dashed lines mark the semimajor axes of P7 and P8. The circular and eccentric planet calculations use identical comet initial states.-- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/Planetary.png?resize=1200%2C604&ssl=1)
Posted inComets and Asteroids
Planetary Eccentricity Enhances Inward Comet Transport But Suppresses Gentle Impacts
[astro-ph.EP] Comets can supply volatile and prebiotic material to rocky planets, but survival of fragile molecules depends on atmospheric entry and impact. Compact planet chains can transfer comets inward at […]
![Median protoplanetary disk composition predicted by the chemical model at different metallicities [Fe/H]. LEFT: Median overall composition. RIGHT: Median refractory composition. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/10/On-the.png?resize=1200%2C719&ssl=1)
Posted inInterstellar
On The Compositions Of Interstellar Objects
[astro-ph.EP] As physical samples of distant planetary systems, the compositions of interstellar objects (ISOs) should correlate with the properties of their diverse parent stars.
Posted inAstrochemistry
Nonequilibrium Formation of C4 Carbonyls in Interstellar Ices Linked to Amino Acids
[ACS Central Science] Complex organic molecules in interstellar ices and carbonaceous asteroids record key steps in the chemical evolution toward life, yet the origin of branched carbonyl compounds a fundamental […]
Posted inComets and Asteroids
Multiband Color Monitoring of 3I/ATLAS Through Ground-Based Relay Observations
[astro-ph.EP] We present multiband, long-baseline photometric observations of interstellar comet 3I throughout its 2025–2026 apparition using coordinated ground-based global relay observations.
![Sky-coverage of the four surveys utilized in this study, with celestial coordinates displayed. It depicts three consecutive observation sectors of TESS, labeled as i−1, i, and i+1. Each of the four TESS cameras is represented by a different color. The beginning of each sector is marked in gray at an ecliptic latitude of 6 deg. The green area indicates the observing region of the fourth camera, which begins at an ecliptic latitude of 78 deg and encompasses the entire ecliptic pole. The magenta, yellow, and grey areas depict the typical 15-day observation coverage of LSST, Pan-STARRS, and ATLAS-W68, respectively. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/1IOumuamua.png?resize=1200%2C717&ssl=1)
Posted inInterstellar
1I/’Oumuamua-like Objects’s SFDs With Older, Current And Future Surveys
[astro-ph.EP] Interstellar Objects (ISOs) may provide direct evidence of planetesimals ejected from early-stage solar systems. Studying these objects and predicting their detection through various surveys is vital for enhancing our […]
![Orbit of 3I/ATLAS showing the 17 UVES/VLT observing epochs. Open and filled circles represent pre- and post-perihelion observations, respectively. Planet positions with filled circles are shown for the date of perihelion. The open diamond marks Earth’s position at the discovery of 3I/ATLAS, while the open circles along Earth’s orbit indicate its position at each observing epoch. [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/High-resolution.png?resize=1200%2C720&ssl=1)
Posted inComets and Asteroids
High-resolution Optical Spectroscopy Reveals The Distinctive Volatile Composition Of The Interstellar Comet 3I/ATLAS
[astro-ph.EP] Comets preserve volatile material from the early stages of planetary-system formation. The discovery of the interstellar comet 3I/ATLAS enables a direct comparison between a comet formed around another star […]
![LDPI–ReTOF mass spectrum obtained after the deposition of 40 ML pure NH3 ice at 15 K (red), without VUV irradiation. A reference mass spectrum obtained for a bare, clean substrate is presented for comparison (black). The spectra are offset for clarity -- [astro-ph.IM]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Quantifying.png?resize=1200%2C720&ssl=1)
Posted inAstrochemistry
Quantifying The Temperature-dependent Yields Of N2 And N2H4 Formation In Vacuum-ultraviolet-irradiated NH3 Ice
[astro-ph.IM] Gas–grain astrochemical models predict that a substantial fraction of elemental nitrogen in dense cores and protoplanetary disks is locked in molecular nitrogen (N2), in the gas or ice phase, […]
Posted inAstrochemistry
JWST Reveals Refractory-Rich Water Ice in Interstellar Comet 3I/ATLAS: Evidence for a Continuum of Grain Properties across Protoplanetary Disks
[astro-ph.EP] We present JWST/NIRSpec PRISM observations of the interstellar comet 3I/ATLAS obtained on 2025 August 6 (Epoch 1), 2025 December 22 (Epoch 2), and 2026 April 1 (Epoch 3), spanning […]
Posted inComets and Asteroids
Fragmentation Dynamics of Pristine Interstellar Comets: An Exploratory Multi-Physics Simulation Study
[astro-ph.EP] We present an exploratory numerical model for the thermal evolution and fragmentation of pristine interstellar comets during a first passage through the inner Solar System, and we apply it […]