Formation of moon systems around giant planets: Capture and ablation of planetesimals as foundation for a pebble accretion scenario

Abstract

The four major satellites of Jupiter, known as the Galilean moons, and Saturn's most massive satellite, Titan, are believed to have formed in a predominantly gaseous circum-planetary disk, during the last stages of formation of their parent planet. Pebbles from the protoplanetary disk are blocked from flowing into the circumplanetary disk by the positive pressure gradient at the outer edge of the planetary gap, so the gas drag assisted capture of planetesimals should be the main contributor to the delivery of solids onto circum-planetary disks. However, a consistent framework for the subsequent accretion of the moons remains to be built. Here we use numerical integrations to show that most planetesimals being captured within a circum-planetary disk are strongly ablated due to the frictional heating they experience, thus supplying the disk with small dust grains, whereas only a small fraction 'survives' their capture. We then construct a simple model of a circum-planetary disk supplied by ablation, where the flux of solids through the disk is at equilibrium with the ablation supply rate, and investigate the formation of moons in such disks. We show that the growth of satellites is driven mainly by accretion of the pebbles that coagulate from the ablated material. The pebble-accreting protosatellites rapidly migrate inward and pile up in resonant chains at the inner edge of the circum-planetary disk. We propose that dynamical instabilities in these resonant chains are at the origin of the different architectures of Jupiter's and Saturn's moon systems. The assembly of moon systems through pebble accretion can therefore be seen as a down-scaled manifestation of the same process that forms systems of super-Earths and terrestrial-mass planets around solar-type stars and M-dwarfs.

20 pages, 13 figures; accepted for publication in A&A

References in corpus (16)

• Coagulation, fragmentation and radial motion of solid particles in protoplanetary disks
• Separating gas-giant and ice-giant planets by halting pebble accretion
• Global simulations of protoplanetary disks with ohmic resistivity and ambipolar diffusion
• The structure of protoplanetary discs around evolving young stars
• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• Dust flow in gas disks in the presence of embedded planets
• Global Simulations of the Inner Regions of Protoplanetary Disks with Comprehensive Disk Microphysics
• Characterization of exoplanets from their formation III: The statistics of planetary luminosities
• Temperature Structure in the Inner Regions of Protoplanetary Disks: Inefficient Accretion Heating Controlled by Nonideal Magnetohydrodynamics
• Dust accretion onto high-mass planets
• Effects of the Planetary Temperature on the Circumplanetary Disk and on the Gap
• On the Viability of the Magnetorotational Instability in Circumplanetary Disks
• Infall of planetesimals onto growing giant planets: onset of runaway gas accretion and metallicity of their gas envelopes
• The Galilean Satellites Formed Slowly from Pebbles
• Pebble accretion at the origin of water in Europa
• Satellitesimal Formation via Collisional Dust Growth in Steady Circumplanetary Disks

Cited by in corpus (21)

• A Circumplanetary Disk Around PDS70c
• Formation of Giant Planet Satellites
• Pebble-driven Planet Formation around Very Low-mass Stars and Brown Dwarfs
• A Tale of Planet Formation: From Dust to Planets
• Meridional Circulation of Dust and Gas in the Circumstellar Disk: Delivery of Solids onto the Circumplanetary Region
• On the Detection of Exomoons Transiting Isolated Planetary-Mass Objects
• An N-body population synthesis framework for the formation of moons around Jupiter-like planets
• Building the Galilean moons system via pebble accretion and migration: A primordial resonant chain
• The fate of planetesimals formed at planetary gap edges
• Circumplanetary disk ices. I. Ice formation vs. viscous evolution and grain drift
• Delivery of gas onto the circumplanetary disk of giant planets: Planetary-mass dependence of the source region of accreting gas and mass accretion rate
• Effective dust growth in laminar circumplanetary discs with magnetic wind-driven accretion
• Size-selective accretion of dust onto CPDs: Low CPD masses and filtration of larger grains
• Predictions of the Nancy Grace Roman Space Telescope Galactic Exoplanet Survey. III. Detectability of Giant Exomoons of Wide Separation Giant Planets
• Survival of satellites during the migration of a Hot Jupiter
• The influence of dust growth on the observational properties of circumplanetary discs
• Forming Massive Terrestrial Satellites through Binary-Exchange Capture
• A constraint on the density of Jupiter's moon Thebe from primordial dynamics
• Interpreting ALMA Multiwavelength Continuum Observations of PDS 70 c: An Optically Thick Dust Ring in the Circumplanetary Disk
• Delivery of complex organic molecules to the system of Jupiter
• Not Just Gas: How Solid-Driven Torques Shaped the Migration of the Galilean Moons