Pebble accretion at the origin of water in Europa

Abstract

Despite the fact that the observed gradient in water content among the Galilean satellites is globally consistent with a formation in a circum-Jovian disk on both sides of the snowline, the mechanisms that led to a low water mass fraction in Europa ($\sim$$8\%$) are not yet understood. Here, we present new modeling results of solids transport in the circum-Jovian disk accounting for aerodynamic drag, turbulent diffusion, surface temperature evolution and sublimation of water ice. We find that the water mass fraction of pebbles (e.g., solids with sizes of 10${}^{-2}$ -- 1 m) as they drift inward is globally consistent with the current water content of the Galilean system. This opens the possibility that each satellite could have formed through pebble accretion within a delimited region whose boundaries were defined by the position of the snowline. This further implies that the migration of the forming satellites was tied to the evolution of the snowline so that Europa fully accreted from partially dehydrated material in the region just inside of the snowline.

Accepted for publication in ApJ

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• The Galilean Satellites Formed Slowly from Pebbles
• Building the Galilean moons system via pebble accretion and migration: A primordial resonant chain
• Early stages of Galilean moon formation in a water-depleted environment
• Constraints on PDS 70 b and c from the dust continuum emission of the circumplanetary discs considering in situ dust evolution
• Circumplanetary disk ices. I. Ice formation vs. viscous evolution and grain drift
• The role of ammonia in the distribution of volatiles in the primordial hydrosphere of Europa
• Journey of complex organic molecules: Formation and transport in protoplanetary disks
• Different arrival times of CM and CI-like bodies from the outer Solar System to the asteroid belt
• Delivery of complex organic molecules to the system of Jupiter