interstellar medium Archives

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

H182O In The Terrestrial Planet-forming Regions Of Protoplanetary Disks

by Keith CowingJanuary 29, 2026January 29, 2026

Isotopologues play an important role in solar system cosmochemistry studies, revealing details of early planet formation physics and chemistry.

A color–magnitude Hess diagram of Sextans A with JWST/ NIRCam photometry at 2.7 and 4.4 μm with the positions of the JWST/LRS targets overplotted. COLIBRI isochrones with [M/H] = −1.7 are plotted for log(age) = 8.3 in orange and log(age) = 9 in blue (P. Marigo et al. 2013), both showing prominent branches of thermally pulsing AGB stars at red colors (F277W − F444W > 0 mag). The population of faint red objects is dominated by unresolved background galaxies and young stellar objects (J. T. Warfield et al. 2023; L. Lenkić et al. 2024). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Press Release

JWST Captures Growth of Aromatic Hydrocarbon Dust Particles in the Extremely Metal-poor Galaxy Sextans A

by Keith CowingJanuary 13, 2026January 13, 2026

The mid-infrared spectrum of star-forming, high metallicity galaxies is dominated by emission features from aromatic and aliphatic bonds in small carbonaceous dust grains, often referred to as polycyclic aromatic hydrocarbons […]

Distribution of the targets observed in this work across the Milky Way in white “+” symbols along with their identifiers, as listed in Table 1. The red asterisk and Sun symbols mark the Galactic centre at (0, 0) kpc and the position of the Solar System at (0, −8.15) kpc, respectively (Reid et al. 2019). The sources are projected onto the Galactic plane with parallax-based distances from Reid et al. (2019). The underlying Milky Way spiral arm pattern follows the log-periodic model from the same study, with colours adapted from Jacob et al. (2022). The background image, is an artist’s impression of the large-scale structure of the Milky Way, courtesy of ESA/Gaia/DPAC/Stefan Payne-Wardenaar. -- astro-ph.GA

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

APEX Survey Of Interstellar HCl: 35Cl/37Cl Isotopic Ratios In Dense Cores And Outflows

by Keith CowingDecember 28, 2025December 28, 2025

Despite being only the 19th most abundant element in the interstellar medium, chlorine’s reactivity and volatility give rise to a unique interstellar chemistry, favouring the formation of several chlorine-bearing hydrides.

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Genomics, Proteomics, Bioinformatics, Imaging & Spectroscopy, Interstellar, Origin & Evolution of Life, Press Release

The Emergence Of Prebiotic Chemistry In The Interstellar Medium (ISM)

by Keith CowingDecember 19, 2025December 19, 2025

Contrary to popular belief, the interstellar medium (ISM) is not empty; it is filled with atoms, dust particles, and molecules.

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

Photochemistry Of Interstellar Ice Forming Complex Organic Molecules

by Keith CowingDecember 16, 2025December 16, 2025

Processes expected to play a role in interstellar ice are simulated in the laboratory. Energetic photons and ions lead to fragmentation or desorption of molecules from the ice. The end […]

A zoomed-in view of NGC1566, one of the 66 galaxies. Left: continuum-subtracted intensity image of the galaxy in the F770W MIRI band. The 2 σ CO intensity contours from PHANGS-ALMA are represented in black. Right: The PAH cloud structures identified by SCIMES are color-coded by their F770W intensities. The green, blue, and red contours indicate the spiral arm, bar, and central region masks, respectively. The interarm region, in this case, consists of the remaining clouds that are not enclosed by the contours. The number of PAH clouds identified in this galaxy is represented in the bottom right. The color bar on top of the image shows the 7.7µm intensity range of the identified clouds. -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Press Release

PHANGS-JWST: The Largest Extragalactic Molecular Cloud Catalog Traced By Polycyclic Aromatic Hydrocarbon Emission

by Keith CowingDecember 8, 2025December 8, 2025

High-resolution JWST images of nearby spiral galaxies reveal polycyclic aromatic hydrocarbon (PAH) emission structures that trace molecular gas, including CO-dark regions.

Set of iCOMs considered in this work. Color code: red for oxygen, white for hydrogen, gray for carbon, and blue for nitrogen. -- The Astrophysical Journal

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

Binding Energies of Interstellar Complex Organic Molecules on Water Ice Surfaces: A Quantum Chemical Investigation

by Keith CowingNovember 10, 2025November 10, 2025

Interstellar dust grains are enveloped by ices of frozen molecules in cold, dense regions of the interstellar medium (ISM), which are also observed in the gas phase.

Depiction of the reaction network of the C2H4 + CH2CCH+ reaction. The energies are calculated at the DLPNO-CCSD(T)/aug-cc-pvtz level with the ωB97XD/def2-TZVPD harmonic zero point energy. In the diagram EQ are used to refer to the wells (local minima) on the PES, TS refer to transition states, and DC means “Dissociation channels”. This nomenclature is chosen to be consistent with the one provided by the GRRM code (Maeda et al. 2023b). -- astro-ph.GA

Astrochemistry, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Imaging & Spectroscopy, Interstellar, Press Release

Ion-molecule Routes Towards Cycles In TMC-1. An Automated Study Of The C2H4 + CH2CCH+ Reaction

by Keith CowingNovember 9, 2025

Cyclopentadiene (c-C5H6) is considered a key molecule in the formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium (ISM).

The normalized JWST spectra of the atomic PDR region and DF3 regions of the Orion Bar (black and red solid lines, respectively) after subtraction of the continuum and plateau emission. The units of the surface brightness are MJy sr−1. For comparison the normalized ISO spectrum of NGC 7027 from Tokunaga & Bernstein (2021) is shown (black dashed line). The JWST spectra of IRAS 21282, M17, NGC 1333, and NGC 2023 (grey solid lines) are from Boersma et al. (2023). Note that the ISO spectrum of NGC 7027 was taken with a 14′′× 20′′ aperture while the JWST spectra were taken with a 3′′ diameter aperture. -- astro-ph.GA

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

A Critical Examination Of The PAH Hypothesis

by Keith CowingNovember 6, 2025November 6, 2025

The polycyclic aromatic hydrocarbon (PAH) hypothesis proposes that the aromatic infrared bands (AIBs) observed at 3.3, 6.2, 7.7, 8.6, 11.3, and 12.7 mic originate from gas-phase PAH molecules.

Channel maps of the D2O emission compared to that of HDO. The grey line indicates the emission above 3σ attributed to the HDO line at 225 GHz. The white contours indicate the 3 and 4σ level for the emission of D2O and the neighbouring COMs. -- astro-ph.EP

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Comets and Asteroids, Exoplanets, -moons, -comets, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Pristine Ices In A Planet-forming Disk Revealed By Heavy Water

by Keith CowingOctober 27, 2025October 27, 2025

Water is essential to our understanding of the planet-formation process and habitability on Earth.

interstellar medium

H182O In The Terrestrial Planet-forming Regions Of Protoplanetary Disks

JWST Captures Growth of Aromatic Hydrocarbon Dust Particles in the Extremely Metal-poor Galaxy Sextans A

APEX Survey Of Interstellar HCl: 35Cl/37Cl Isotopic Ratios In Dense Cores And Outflows

The Emergence Of Prebiotic Chemistry In The Interstellar Medium (ISM)

Photochemistry Of Interstellar Ice Forming Complex Organic Molecules

PHANGS-JWST: The Largest Extragalactic Molecular Cloud Catalog Traced By Polycyclic Aromatic Hydrocarbon Emission

Binding Energies of Interstellar Complex Organic Molecules on Water Ice Surfaces: A Quantum Chemical Investigation

Ion-molecule Routes Towards Cycles In TMC-1. An Automated Study Of The C2H4 + CH2CCH+ Reaction

A Critical Examination Of The PAH Hypothesis

Pristine Ices In A Planet-forming Disk Revealed By Heavy Water

Well-Preserved Polygons In Elysium Planitia on Mars

Long-term Performance Of Thermoacidophilic Methanotrophic Biotrickling Filters

Diversity Of Planetary Origins And Compositions Traced By Stellar Abundance Differences Of Co-natal Star Systems

Coupled Evolution Of Earth’s H2-rich Proto-atmosphere And Oxidized Magma Ocean

Prebiotic Synthesis of L-Homochiral Peptides on Primordial Earth