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

Ronnet, T. LU and Johansen, A. LU (2020) In Astronomy and Astrophysics 633.
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 that are captured within a... (More)

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 that are 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 constructed 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 we investigate the formation of moons in such disks. We show that the growth of satellites is mainly driven 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.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
formation, Galilean moons, gaseous planets, individual, Planets and satellites, Titan
in
Astronomy and Astrophysics
volume
633
article number
A93
publisher
EDP Sciences
external identifiers
  • scopus:85085282215
ISSN
0004-6361
DOI
10.1051/0004-6361/201936804
language
English
LU publication?
yes
id
d0b7576d-01fb-4faa-8a7b-5580aef4fcba
date added to LUP
2020-12-28 14:21:30
date last changed
2023-01-01 02:43:53
@article{d0b7576d-01fb-4faa-8a7b-5580aef4fcba,
  abstract     = {{<p>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 that are 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 constructed 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 we investigate the formation of moons in such disks. We show that the growth of satellites is mainly driven 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. </p>}},
  author       = {{Ronnet, T. and Johansen, A.}},
  issn         = {{0004-6361}},
  keywords     = {{formation; Galilean moons; gaseous planets; individual; Planets and satellites; Titan}},
  language     = {{eng}},
  publisher    = {{EDP Sciences}},
  series       = {{Astronomy and Astrophysics}},
  title        = {{Formation of moon systems around giant planets : Capture and ablation of planetesimals as foundation for a pebble accretion scenario}},
  url          = {{http://dx.doi.org/10.1051/0004-6361/201936804}},
  doi          = {{10.1051/0004-6361/201936804}},
  volume       = {{633}},
  year         = {{2020}},
}