Temporal evolution of selected species and D/H ratios during the cloud (top panels) and core stages (lower panels). Panels (a) and (e) show the abundances of selected species during the cloud and core stages, respectively. Solid, dashed, and dotted lines denote models with Z = 1, 0.5, and 0.2, respectively. The remaining panels show the temporal evolution of the D/H ratios and the H2 OPR for Z = 1 (b, f), Z = 0.5 (c, g), and Z = 0.2 (d, h). In all panels, time is normalized by τfreeze for the corresponding density and metallicity. -- [astro-ph.EP]

High Water D/H Ratio of the Interstellar object 3I/ATLAS is Consistent With a Low-metallicity Origin

by Keith CowingSeptember 16, 2026September 16, 2026

[astro-ph.EP] Recent JWST observations have revealed unusually high 12C/13C ratios in carbon-bearing molecules of the interstellar object 3I/ATLAS, consistent with formation in a lower-metallicity environment than the present-day local interstellar […]

This artist’s concept depicts a Trans-Neptunian Object, a small, faint, icy body orbiting the Sun beyond the orbit of Neptune. These objects are so small that even with NASA’s Hubble and Webb space telescopes, they appear only as tiny points of light. Artwork: NASA, ESA, Leah Hustak (STScI)

Astrogeology

Trans-Neptunian Objects Remember Their Past

by Keith CowingSeptember 9, 2026September 9, 2026

[NASA]. For the first time, scientists used the joint power of NASA’s Hubble and James Webb Space Telescopes to study some of the most far-flung bodies in our solar system, […]

Uncategorized

Multi-Wavelength Post-Perihelion Polarimetry of Interstellar Comet 3I/ATLAS

by Keith CowingSeptember 8, 2026September 8, 2026

[astro-ph.EP] We present new post-perihelion polarimetric observations of the third discovered interstellar object, 3I/ATLAS (C/2025 N1; hereafter 3I), obtained using FORS2 at the Very Large Telescope, ALFOSC at the Nordic […]

LT solution with 2036 launch. Continuous thick curve: trajectory, Short segments: thrust law, Dashed lines: planet and comet orbits. -- [astro-ph.EP]

Comets and Asteroids

Double Gravity-Assist Rendezvous Trajectory to Halley’s Comet Using Deep-Space Low Thrust

by Keith CowingSeptember 6, 2026September 6, 2026

[astro-ph.EP] The perihelion of comet 1P/Halley in 2061 is an excellent chance to revisit this object of outstanding scientific and cultural relevance. During its 1986 approach to the Sun, it […]

Schematic of PDS 70, containing PDS 70 b and PDS 70 c in black, and the inner and outer discs in orange

Exoplanets, -moons, -comets

Comets May Have Transported Water To A Young Planetary System

by Keith CowingSeptember 3, 2026September 3, 2026

[Lund University] Astronomers at Lund University in Sweden have found evidence of exocomets – comets in other solar systems – orbiting a young star similar to our Sun. The observations […]

Occam’s razor-based deconvolution result of the subset of signals associated with CnHmN parent and fragment species detected by the DFMS on 3 August 2015. The measured signals (measured) are given in arbitrary units (a. u.) with 30 % error margins. The different contributions of the chosen candidate molecules are colour-coded according to their molecular structure – in shades of red and purple for chain-based molecules and in shades of green and blue for cyclic molecules. -- [astro-ph.EP]

Comets and Asteroids

Nitrogen- And Nitrogen-oxygen-bearing Organic Molecules In Comet 67P/Churyumov-Gerasimenko: An Untargeted Investigation

by Keith CowingAugust 27, 2026August 27, 2026

[astro-ph.EP] Comets provide a unique window into the history of the Solar System as they carry some of the best-preserved material and make it available to in situ exploration.

Example of the stacking procedure for the Maidanak data obtained on 2025 August 15, based on ten 60 s exposures in each of the B, V , and R filters. Left: Comet-centered stack, showing the coma morphology without trailing of the comet signal. The pink circle indicates an aperture radius of 10 000 km. Right: Sidereal stack used for photometric calibration, in which the comet appears trailed.-- [astro-ph.EP]

Comets and Asteroids

The Inbound Gas and Dust Evolution of Interstellar Comet 3I/ATLAS from Optical Spectroscopy and Multi-band Photometry

by Keith CowingAugust 24, 2026August 24, 2026

[astro-ph.EP] Interstellar objects (ISOs) provide direct constraints on the composition and evolution of extrasolar planetary systems. As the third confirmed ISO, comet 3I/ATLAS offers a rare opportunity to study pristine […]