CO snowline Archives - Astrobiology

[LEFT] Evolution of the fiducial full 2D simulation. The simulation has run for ∼ 4 Myr; line opacity increases with time in intervals of 0.4 Myr. The top row shows the surface densities of dust (ice included), ice and vapour, whilst the second row shows the mid-plane temperature. The small noncontinuous deviations in the surface density appear due to integration over the tightly-constrained, discontinuous vertical structure of the ice. [RIGHT] Spatial distributions of CO ice and vapour density in the full 2D fiducial simulation. Temperature contours (in K) are over-plotted for reference. -- astro-ph.EP

CO Snow Lines Are Stabilised By The Vertical Transport Of Volatiles

by Keith CowingJuly 5, 2026July 5, 2026

[astro-ph.EP] Volatile evolution in protoplanetary discs determines the compositional evolution of forming planets. Below their sublimation temperatures, volatiles freeze out from the vapour phase onto dust grains in the disc […]

Azimuthally averaged gas density (left) and gas radial velocity relative to the planet (right) for our FARGO3D disk model containing a Jupiter mass planet at 75 au. The CO sublimation surface at 30 K recovered from our RADMC-3D model is indicated in both panels by the red dashed line. The region near the embedded planet is heated from a combination of accretion heating onto the planet, disk viscous heating, and radiative heating from the star, resulting in higher temperatures at the midplane in the gap. Gas advection relative to the local sound speed is also indicated by white arrows. Gas advection is primarily outward along the midplane near the planet, with significant vertical flows away from the midplane at the gap edge and in the pressure bump at 100 au. -- astro-ph.EP

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

Dust Recycling and Icy Volatile Delivery (DRIVE): A Novel Method of Volatile Enrichment in Cold Giant Planets

by Keith CowingNovember 13, 2025November 13, 2025

Giant planet atmospheres are thought to reflect the gas phase composition of the disk when and where they formed.

Upper panel: top view of one of the non-porous (npASW) (left) and porous (pASW) ice models. Each periodic surface contains 500 water molecules. Lower panel: altitude plot relative to the same two structures (see Appendix D). Periodic cell dimensions are included. Distances in Å. -- astro-ph.GA

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

CO Adsorption Sites On Interstellar Water Ices Explored with Machine Learning Potentials. Binding Energy Distributions And Snowline

by Keith CowingAugust 21, 2025August 21, 2025

Context. Carbon monoxide (CO) is arguably the most important molecule for interstellar organic chemistry. Its binding to amorphous solid water (ASW) ice regulates both diffusion and desorption processes. Accurately characterizing […]

Dynamical excitation of the planetesimal disk at 0.75, 2 and 5 Myr in the four simulated scenarios. Dynamical excitation accounts for the contributions of both eccentricity and inclination and is defined as p e 2 + sin2 (i) (Petit et al. 2001). The colour bar indicates the region in the disk from which the planetesimals originated (in units of au). The dashed grey line at 40 au indicate the division between inner and outer disk. The rectangles in the rightmost panels mark the “fountain” feature we refer to in the main text, i.e. the damping of the orbital eccentricities of the excited planetesimals by aerodynamic drag that creates the implanted planetesimals. The light blue filled circles indicate the location of the four simulated planets in the disk. First row: High Disk Mass - High Planetary Mass; Second row: High Disk Mass - Low Planetary Mass; Third row: Low Disk - High Planetary Mass; Fourth row: Low Disk Mass - Low Planetary Mass -- astro-ph.EP

Astrochemistry, Astrogeology, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Brown Dwarfs, Comets and Asteroids, Exoplanets, -moons, -comets, Gas Giants, Icy Worlds, Imaging & Spectroscopy, Interstellar, Status Report

HD 163296 And Its Giant Planets: Creation Of Exo-comets, Interstellar Objects And Transport Of Volatile Material

by Keith CowingMarch 11, 2025March 11, 2025

The birth of giant planets in protoplanetary disks is known to alter the structure and evolution of the disk environment, but most of our knowledge focuses on its effects on […]

Schematic illustrating transport mechanisms of volatiles that produce the C/H enhancement seen within the CO snowline in HD 163296 as observed by Zhang et al. (2020). The process begins in the outer disc with dust growing to pebbles as the CO and water vapour freeze out onto the pebbles. As the grains grow, they decouple from the gas and drift inwards towards the CO snowline; within the snowline, the CO sublimates and enhances the C/H ratio of the gas and vapour present; the CO vapour is transported to the upper layers of the disc via diffusion. It also advects inwards, indicated by the grey arrows. Water ice remains on the pebbles and is transported further inward as the pebbles continue to drift toward the water snowline, which is around 1 AU in our model in this paper. Here, water sublimates and becomes readily available for planet formation in the region where terrestrial planets may be forming. Note that the illustrated emission line probe region is specific to CO rotational lines in this context. This schematic was inspired by Fig. 2 of Cuzzi & Zahnle (2004). -- astro-ph.EP

Astrochemistry, Astrogeology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Interstellar, Status Report

The CO-Fuelled Time Machine: Tracing Birth Conditions and Terrestrial Planet Formation Outcomes in HD 163296 through Pebble Drift-induced CO Enhancements

by Keith CowingJanuary 11, 2025January 11, 2025

The architecture and composition of planetary systems are thought to be strongly influenced by the transport and delivery of dust and volatiles via ices on pebbles during the planet formation […]