Icy Volatile Enhancements in Evolving Protoplanetary Disks

2026/04/15 by Elizabeth Yunerman, Ellen Price, Karin Öberg · 1 voice
Physics and Astronomy · #astro-ph.EP

paper · pdf · doi:10.3847/1538-4357/ae60fe

Abstract

Protoplanetary disk ice lines shape a multitude of planet formation processes, setting the environmental composition through evolution. Ice line locations depend on molecular sublimation and deposition properties, but in dynamic disks where temperature and density structures change, so do the expected compositions of planets and planetesimals. In turbulent viscous disks with particle drift, thermal evolution, and desorption/adsorption, Price et al. 2021 demonstrated that the CO/H₂O ice ratio beyond the CO ice line can become enhanced by ∼10×. We expand on their work by incorporating additional carbon, nitrogen, and oxygen species, more particle sizes, and a broader disk parameter exploration. We find that before ∼0.5Myr, volatile ices are enhanced relative to H₂O as the outer disk is desiccated by drift, while at later disk times outward advection and volatile deposition further increase relative volatile icy enhancements beyond the evolving critical disk radius. The outcome of these combined relative icy enhancement to H₂O mechanisms is solid C/O ∼ N/O ∼1 beyond the hypervolatile ice lines, much higher than expected in static disks. Hypervolatiles (N₂, CO, and CH₄) robustly increase to ∼100× across the explored parameter space, while mid-volatiles (CO₂ and NH₃) are sensitive to model choices, with enhancements ranging from ∼2-50×. Together these results demonstrate that coupling disk dynamics with simple sublimation and deposition chemistry is fundamental to predicting grain, planetesimal, and planetary compositions, particularly the role of advection in redistributing volatiles across disk radii.

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Discussions

• Icy Volatile Enhancements in Evolving Protoplanetary Disks Yunerman et al. arXiv (ApJ) arxiv.org/abs/2604.14124 [bsky, 1 points, 0 comments]