astrochemistry Archives

This artist’s impression compares the semi-heavy water content of the interstellar comet 3I/ATLAS (left) and Earth (right). Insets illustrate the relative abundance of deuterated water (HDO) molecules, showing that 3I/ATLAS contains over 30 times more HDO than is found in Earth’s oceans. This elevated ratio suggests the comet formed in an extremely cold environment, very different from the conditions that shaped our Solar System. Credit: NSF/AUI/NSF NRAO/M.Weiss

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

ALMA Reveals Interstellar Comet 3I/ATLAS Formed in a Far Colder World Than Our Own

by Keith CowingApril 23, 2026April 23, 2026

New observations from the Atacama Large Millimeter/submillimeter Array (ALMA) have yielded the first-ever measurement of deuterated water — also known as semi-heavy water — in an interstellar object. The discovery […]

The (H2O)18 cluster used in the present work, optimized at the B97X-D3/def2-TZVP level. Panels a, b, and c represent the three different initial N2 adsorption sites. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Status Report

The Reaction Between Atomic Carbon And Molecular Nitrogen As A Source Of Cyanamide And Carbodiimide On Interstellar Ices

by Keith CowingApril 23, 2026April 23, 2026

Reactions occurring on the ice-covered surfaces of interstellar dust grains are considered to be among the most important sources of complex species in the interstellar medium. Despite this, molecules such […]

SLC of comet 3I/ATLAS. The MPC observations show a much larger dispersion of the data than the COBS observations. There is a significant increase in brightness starting at -45 days before perihelion that we interpreted as the onset of water sublimation. The maximum reduced magnitude reached by the comet was mV(max)=6.8±0.15 mag. This plot and the next one may be considered as two of the highlights of the SLC Methodology. The other highlight is the Comet Evolutionary Diagram. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Interstellar, Status Report

Secular Light Curve of Exocomet 3I/ATLAS, and its Location on a Comet Evolutionary Diagram

by Keith CowingApril 23, 2026April 23, 2026

In this work we will create the Secular Light Curve (SLC) of exocomet 3I/ATLAS, using the SLC-Methodology (Ferrin 2010-2023). The SLCs give a throve of new information and allow the […]

Representative adsorption geometries for HCSCN (panels a–c) and HCSCCH (panels d–f) on the TIP4P (𝐻2𝑂)10 cluster at the 𝜔B97XD/def2-TZVP level of theory, illustrating the three structurally distinct binding topologies sampled across the full 𝑛 = 6–16 survey. Atom colours: O (red), H (white), C (tan), N (blue), S (yellow); cyan distances mark resolved intermolecular hydrogen-bond contacts. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Ice as a Photochemical Shield: Adsorption Energetics and Spectroscopic Modulation of Interstellar Thiocyanates HCSCN and HCSCCH in TMC-1

by Keith CowingApril 22, 2026April 22, 2026

The recent detections of thioformyl cyanide (HCSCN) and propynethial (HCSCCH) in TMC-1 provide critical insights into the interstellar sulfur inventory, yet their sequestration and survivability on dust grain mantles remain […]

Predicted relative transit depth change from the equilibrium chemistry CO2-only model retrieved for CRIRES+ data (green). The model predictions are plotted in high-resolution in the wavelength region overlapping with the CRIRES+ measurements indicated by the grey shaded areas and in low-resolution for the rest of the wavelength range. Space-based measurements from HST (blue) and JWST (orange) are also shown. The 1σ and 1.5σ uncertainties of the model are indicated as darker and lighter green shaded areas, respectively. We also mark the lower 1.1σ uncertainty boundary with a dotted green line as a potential match to the amplitude of the CO2 bump in the JWST measurements at 4200 nm. The HST-WFC3 and JWST NIRSpec G359H measurements were taken from the online data provided by Schlawin et al. (2024) containing the HST data adapted from Kreidberg et al. (2014).-- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Cloudy With A Chance Of Metals: Indications Of CO2 In The Atmosphere Of GJ 1214 b From High-resolution K-band Spectroscopy

by Keith CowingApril 19, 2026April 19, 2026

Sub-Neptune exoplanets frequently exhibit muted transmission spectra, with GJ 1214 b being the most prominent example. Following years of intense observing campaigns yielding featureless planetary spectra, recent observations with JWST […]

a) Large area EDS map of Nantan meteorite sample showing the distribution of detected elements. b) XPS SnapMaps of Nantan fragment showing the distribution of Fe and Ni. c) XRF maps of individual elements detected, with a focus on Fe and Ni. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Meteorites & Asteroids, Sample Return, Status Report

Correlative Microstructural Analysis of a Weathered Nantan Meteorite Fragment

by Keith CowingApril 19, 2026April 19, 2026

The weathering of iron-rich phases within meteorites is a multi-stage process that significantly alters the microstructure and chemical composition based both on the environmental condition at the location of landing […]

Top row: coma maps of H2O, CO2, and CH4, computed as the molecular column density from a pixel-by-pixel retrieval analysis for Observations 6, 15, and 6, respectively. The sunward and target velocity directions are denoted by the white arrows. The target centroids, computed as the photocenter in the median-stacked images (Figure 1), are marked with the black points. For H2O and CO2, the white contours correspond to emission levels of 50% and 20% relative to the maximum value and illustrate the slight anti-sunward extension of the respective comae. The contours are omitted in the CH4 panel due to the poorer signal-to-noise ratio of the data. Bottom row: corresponding median-stacked images across the continuum wavelengths within each fluorescence region. The H2O coma map shows significant enhancement in emission level at large nucleocentric distances relative to the dust continuum, indicating extended H2O production within the coma. -- arxiv.org

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Intelligence & Language, Interstellar, Press Release

Interstellar Comet Reveals Methane On Its Journey Through Our Solar System

by Keith CowingApril 18, 2026April 18, 2026

Interstellar comet 3I/ATLAS is now on its way out of our solar system, never to return.

[LEFT] Final planet mass vs pebble flux across the snowline at time of insertion. Plots A and B are coloured by the planet’s initial and final semi-major axes respectively. Plot C is coloured by the planet’s insertion time 𝑡0, and plot D is coloured by the characteristic disk radius 𝑅0. Plot E is coloured by the disk’s 𝛼 parameter, and plot F is coloured by the fragmentation velocity 𝑣frag. All plots contain outlined numbered points, which correspond to the points numbered in Fig. 2. [RIGHT Final planet mass vs pebble flux across the snowline at 1 Myr. Plots A and B are coloured by the planet’s final and initial semi-major axes respectively. Plot C is coloured by the planet’s insertion time 𝑡0, and plot D is coloured by the characteristic disk radius 𝑅0. Plot E is coloured by the disk’s 𝛼 parameter, and plot F is coloured by the fragmentation velocity 𝑣frag. All plots contain outlined numbered points, which correspond to the points numbered in Fig. 2. -- astro-ph.EP

Astrochemistry, Astrogeology, Comets and Asteroids, Exoplanets, -moons, -comets, Status Report

Simulating The Interplay Between The Snowline Pebble Flux And Ongoing Planet Formation And Migration

by Keith CowingApril 18, 2026April 18, 2026

Pebble drift plays a central role in modern planet formation models. In this work we carry out planet formation simulations (including pebble accretion and migration) for a range of disc […]

Outer disk regions become increasingly H2O ice poor as compared to dominating N2, CO, and CO2 ices over a disk’s lifetime. The leftmost pie displays the assumed initial abundances across all species that arrive in the disk frozen-out on solid particles. Individual species making up the total volatile ice composition are labeled and color-coded. Radial ice abundances from 1 to 300 au are displayed at 3 Myr in the six small pies to the right of the initial abundances. Species labels are only included in the radial 3 Myr pies if their ice abundance makes up at least 10% of the total ice composition. Displayed to the right of the 3 Myr radial ice composition pies are those of representative solar system carbon-depleted and carbon-enriched comets adapted from D. Jewitt & D. Z. Seligman (2023), which use the average of measured H2O, CO2, and CO ice production rates from a number of solar system and interstellar comets for the carbon-depleted comet, detailed in D. Z. Seligman et al. (2022), and comet C/2006 W3 (Christensen) from T. Ootsubo et al. (2012) for the carbon-enriched case. Refractory species are not considered in these pies, only volatile species. -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Status Report

Icy Volatile Enhancements in Evolving Protoplanetary Disks

by Keith CowingApril 17, 2026April 17, 2026

Protoplanetary disk ice lines shape a multitude of planet formation processes, setting the environmental composition through evolution.

The formation mechanism of the lower haze. Cosmic dust entering from space is incorporated into sulfuric acid clouds. As sulfuric acid evaporates at the cloud base, the dust particles remain and coagulate to form the lower haze. ©Hiroki Karyu et al.

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Status Report, Venus

Cosmic Dust Identified As The Source Of Venus’ Enigmatic Lower Haze

by Keith CowingApril 17, 2026April 17, 2026

Venus, often called Earth’s twin, is in fact a planet of extremes. Beneath its thick carbon dioxide atmosphere lie crushing surface temperatures and dense clouds of sulfuric acid. While the […]

astrochemistry

ALMA Reveals Interstellar Comet 3I/ATLAS Formed in a Far Colder World Than Our Own

The Reaction Between Atomic Carbon And Molecular Nitrogen As A Source Of Cyanamide And Carbodiimide On Interstellar Ices

Secular Light Curve of Exocomet 3I/ATLAS, and its Location on a Comet Evolutionary Diagram

Ice as a Photochemical Shield: Adsorption Energetics and Spectroscopic Modulation of Interstellar Thiocyanates HCSCN and HCSCCH in TMC-1

Cloudy With A Chance Of Metals: Indications Of CO2 In The Atmosphere Of GJ 1214 b From High-resolution K-band Spectroscopy

Correlative Microstructural Analysis of a Weathered Nantan Meteorite Fragment

Interstellar Comet Reveals Methane On Its Journey Through Our Solar System

Simulating The Interplay Between The Snowline Pebble Flux And Ongoing Planet Formation And Migration

Icy Volatile Enhancements in Evolving Protoplanetary Disks

Cosmic Dust Identified As The Source Of Venus’ Enigmatic Lower Haze

Astrobiologist Dale Andersen’s Antarctic Field Report: 9 November 2026: Lake Untersee Basecamp Update

Astrochemistry: Hubble and JWST Observe Star Formation in The Carina Nebula

Mapping the Historical Roots of Astrobiology: A Reference Publication Year Spectroscopy (RPYS) Analysis

The Agentic Observer Hackathon: Autonomous Decision-making in Simulated Astronomical Surveys

Tracking The Evolution of sub-Neptunes. I. Gyrochronology of Planet Hosting Stars