67P/Churyumov-Gerasimenko Archives

Images of comet 7P/Pons–Winnecke taken during a period of quiescence (left, taken at 2021 July 28 10:25:23 UTC) and the 2021 July 10 outburst (right, taken at 2021 July 10 02:29:58 UTC). The outburst ejecta is apparent as distortions in the observed surface brightness as compared to the ambient coma image. The bottom row shows the logarithmically scaled data with contours spaced every 0.5 mag/arcsec2 . A color bar provides the surface brightness scale. Images are oriented with north up, and east to the left. -⊙ represents the anti-solar direction and V is the heliocentric velocity direction, and a linear scale bar is shown. The blue arrows highlight two linear features as a result of the ejecta distribution that are meeting at a near-right angle in front of the nucleus. -- astro-ph.EP

A Look At Eight Outbursts Of Comet 7P/Pons-Winnecke

by Keith CowingJune 26, 2026June 26, 2026

Cometary outbursts may be used as a means to infer the physical processes occurring on cometary nuclei. To that end, we studied eight outbursts of comet 7P/Pons-Winnecke identified between 2021 […]

D/H ratios in solar system and extrasolar sources. Ratios are for methane except when noted otherwise. Sources for which the D/H ratio in c−C3H2 was used to estimate the D/H in CH4 are denoted with a ⋆. References and values for each object are given in Extended Data Table 3. -- astro-ph.EP

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

Isotopic Signature of Organic Molecules from Beyond the Solar System: An Enriched Methane D/H Ratio in the Interstellar Object 3I/ATLAS

by Keith CowingMarch 27, 2026March 27, 2026

Interstellar objects are interlopers from other planetary systems, and their volatile compositions provide a glimpse into planet formation around their host star. We present near-infrared spectra of the coma of […]

Averaged 18 cm OH lines (scaled to 1667 MHz) of 3I obtained in four observations with both a Gaussian and a trapezoid fit: September 8 and 9 (top), September 18 and 23 (bottom). The Astrophysical Journal

Astrochemistry, Astronomy & Telescopes, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Unique Water Release Mechanism Uncovered In Interstellar Comet 3I/ATLAS

by Keith CowingMarch 23, 2026June 11, 2026

A research team from the Shanghai Astronomical Observatory (SHAO) of the Chinese Academy of Sciences (CAS) has conducted high-sensitivity radio observations of the interstellar comet 3I/ATLAS using the Tianma Telescope, […]

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report

Recent Chemo-morphological Coma Evolution of Comet 67P/Churyumov-Gerasimenko

by Keith CowingJuly 21, 2025July 21, 2025

We present VLT/MUSE observations of comet 67P/Churyumov-Gerasimenko during its 2021 perihelion passage, from which we generated simultaneous maps of dust, [OI], C2, NH2, and CN comae across 12 pre- and […]

Water ice absorption bands taken on Nov. 2. The normalized spectrum (blue circles) is compared with the best-fit model (red line) and two alternative models in which the ice compositions are amorphous ice at 120 K (dashed lines) and crystalline ice at 80 K (dash-dotted lines). The error bars account for both random and systematic errors. Systematic errors in the JHK bands are estimated band-wise using the standard deviation within the continuum regions of 1.25–1.34, 1.70–1.80, and 2.15–2.45 µm, respectively. -- astro-ph.EP

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

Optical And Near-Infrared Spectroscopy Of The Outbursting Comet 12P/Pons-Brooks

by Keith CowingJuly 9, 2025July 9, 2025

We present optical and near-infrared (NIR) observations of the outbursting, Halley-type comet 12P/Pons-Brooks.

The 134Xe/132Xe versus 136Xe/132Xe diagram showing the composition of Tatahouine (#13349) and Shalka (#6766 C) measured at different heating steps, including those of Michel & Eugster (1994) and Eugster & Michel (1995) for comparison. The 238U and 244Pu fission Xe data are from Porcelli et al. (2002). Q-Xe (Q phase is the main carrier of heavy noble gases in chondrites) is from Busemann et al. (2000), SW-Xe (SW stands for solar wind) is from Meshik et al. (2020), U-Xe is from Pepin & Porcelli (2002) and Air (corresponding to Earth’s atmosphere) -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Gas Giants, Meteorites & Asteroids, Status Report

Asteroids Fail To Retain Cometary Impact Signatures

by Keith CowingJuly 3, 2025July 3, 2025

A bombardment of comets is thought to have occurred in the inner solar system as a result of a dynamical instability among the giant planets after gas disk dispersal.

The ER potential energy surface along the minimum energy path for (a) H atom approaching an hydroxyl group from infinity and (b) H2 molecule abstraction from the enstatite nanocluster. -- astro-ph.GA

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Comets and Asteroids, Imaging & Spectroscopy, Press Release

Hydroxylated Mg-rich Amorphous Silicates as Catalysts for Molecular Hydrogen Formation in the Interstellar Medium

by Keith CowingJune 17, 2025June 17, 2025

We present results from an experimental study on the interaction of atomic deuterium with Mg-rich amorphous enstatite and forsterite type silicates. Infrared spectroscopy was used to examine the process.

Identified COMs towards the disk of V883 Ori. The horizontal dotted line in gray represents the noise level in the data (1σ), the black line represents the data, and different colors represent the best fit of the model of different species. --astro-ph.GA

Astrochemistry, Astrogeology, Astronomy & Telescopes, Biochemistry & Organic Chemistry, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

A Deep Search For Complex Organic Molecules Toward The Protoplanetary Disk Of V883 Ori

by Keith CowingApril 9, 2025September 18, 2025

Complex Organic Molecules (COMs) in the form of prebiotic molecules are potentially building blocks of life.

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Status Report

Primordial Origin of Methane on Eris and Makemake Supported by D/H Ratios

by Keith CowingMarch 26, 2025March 26, 2025

Deuterium, a heavy isotope of hydrogen, is a key tracer of the formation of the Solar System. Recent JWST observations have expanded the dataset of D/H ratios in methane on […]