Astrochemistry

Carbon From Interstellar Clouds To Habitable Worlds

By Keith Cowing
Press Release
February 12, 2026
Filed under , , , , , , ,
Carbon From Interstellar Clouds To Habitable Worlds
Schematic of some of the key processes throughout planet formation that influence carbon supply and retention. (a) Key ice/grain sublimation fronts in the disk noted (CO2 between water–CO and that of Silicates at inner disk edge not shown). Planets forming in these locations will receive different compositions at birth (Öberg et al. 2011). Dust that grows beyond the “soot” line (Lodders 2004, Kress et al. 2010, Li et al. 2021) will be rich in refractory carbon content and at greater distances molecular ices. (blow-out:) The drift of carbon-rich pebbles from the outer disk is a key process in carbon supply. Drift itself is influenced by pressure bumps that can lead to a pile-up of pebbles that can be potential sites for planetesimal and planet formation (shown on left side of disk). (b) Solids accrete ice mantles, sublimate key components at sublimation fronts and can collide leading to both growth and fragmentation. (c) Rocky planets and cores of gas-rich planets grow and gain carbon through accretion of pebbles (top) and/or planetesimals (bottom). Impacts of larger planetesimals can also strip atmospheric gas and also supply material. (d) heavy element differentiation can take carbon to the core, and the resulting magma ocean/atmosphere equilibrium can influence atmospheric composition with lighter gases escaping depending on the planet mass. Figure credit to N. Fuller and Sayo Studio. — astro-ph.EP

Carbon is an essential element for a habitable world. Inner (r < 3 au) disk planetary carbon compositions are strongly influenced by supply and survival of carbonaceous solids. Here we trace the journey of carbon from the interstellar medium to the processes leading to planet formation. The review highlights the following central aspects:

  • Organics forming in evolved star envelopes are supplemented by aromatic molecules forming in the dense ISM to represent the seeds of (hydro)carbon supply through pervasive pebble drift to rocky planets and sub-Neptune cores.
  • Within the protoplanetary disk the sharp gradient in the C/Si content of Solar System bodies and mineral geochemistry outlines a tale of carbon loss from pebbles to within planetesimals and planets, and from planetary atmospheres.
  • Within two planet formation paradigms (pebble and planetesimal accretion) a range of planetary carbon content is possible that is strongly influenced by early (< 0.5 Myr) formation of a pressure bump that titrates drift.

Overall, it is unlikely that the carbon architecture of our Solar System applies to all systems. In the absence of giant planets, carbon-rich rocky worlds and sub-Neptunes may be common. We outline observations that support their presence and discuss habitability of terrestrial worlds.

Edwin A. Bergin, Marc M. Hirschmann, Andre Izidoro

Comments: Review to be published in Annual Reviews of Astronomy and Astrophysics Volume 64 (authors version, 52 Pages, 14 figures, 2 tables)
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2602.10308 [astro-ph.EP] (or arXiv:2602.10308v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2602.10308
Focus to learn more
Submission history
From: Edwin A. Bergin
[v1] Tue, 10 Feb 2026 21:27:06 UTC (33,165 KB)
https://arxiv.org/abs/2602.10308
Astrobiology, Astrochemistry,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

Follow on Twitter
MORE FROM Astrochemistry