From planetary embryos to planetary systems:
integrated models of planet formation
Yann ALIBERT
Q1 of ELSI: What is the origin of the Earth?
Outline
1- Planet formation
2- Why do we need to consider giant planets
3- Integrated models
Planet formation
1- Planet formation
2- Why do we need to consider giant planets
3- Integrated models
Planet formation
2.5 Light years ~160000 AU
NGC2264
1000 AU
~100s AU
Model
Giant planets form by accreting gas from protoplanetary disks
Protoplanetary disks: observations
HH-30; Burrows et al.;NASA Protoplanetary disks in the Orion Nebula; HST
disks lifetime gives maximum formation time Giant planets must form in < 10 Myr
disks mass and gas-to-solids ratio give available material Typical mass from 0.001 to 0.1
Msun
Extrasolar planets: observations
The disk instability model
Mayer et al. 2004
Origin of enrichment in heavy elements/formation of low mass (Earth,Neptune) planets?
Clump formation depends critically on disk cooling
formation of massive planets
formation in outer parts of the disk
The nucleated instability model (1)
+ +
+
embryoPlanetThe nucleated instability model (2)
gas giant ice giant
terrestrial planet
Giant planets and planetary systems
1- Planet formation
2- Why do we need to consider giant planets
3- Integrated models
Walsh et al. 2011
gap merging
outward migration
resonant system
}
Formation of the Solar System - the Grand Tack model
Walsh et al. 2011
Formation of the Solar System - the Grand Tack model
Mixing of asteroids Formation of terrestrial planets possible source of water on Earth
Integrated models
1- Planet formation
2- Why do we need to consider giant planets
3- Integrated models
Processes involved during planet formation
planetesimal-planetesimal interactions gas disk structure and evolution
planetesimal accretion
planetesimal-gas disk interactions planet-disk interactions
planet internal structure and gas capture planet-planet interactions
many others
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Integrated models
1000 AU
What is the effect of the combined processes in shaping planetary systems?
Integrated models
specialized models
integrated models
extraction
process
- while you get the essence, you have lost the subtlety of the original
- but what is left is a concentrate of many effects
- and lets you see the big picture (hopefully)
- you need specialized models to know what is important
Disk truncation by magnetic field
excitation accretion
ang. momentum exchange -
eccentricity damping
gas drag ang. momentum
exchange - eccentricity damping
grav.
interactions
Irradiation Bern model
Seen from the edge protoplanetary disk = gas disk + planetesimals
gas disk
number of growing planets (initially of Moon mass) is a free parameter
Mass (Earth masses)
Semi-major axis (AU)
Time
fraction of icy planetesimals
Icy
Rocky Mercury
1 planetary system - 10 planetary seeds/system
Population synthesis
lifetime mass
Population synthesis
specialized models
integrated models
extraction
process
- while you get the essence, you have lost the subtlety of the original
- but what is left is a concentrate of many effects
- and lets you see the big picture (hopefully)
- you need specialized models to know what is important
Run the formation model with many different initial conditions
0.1 1 10
Semi major axis [AU] 1e 01 1e+00 1e+01 1e+02 1e+03 1e+04
Mass [M ]0 0.2 0.4 0.6 0.8 1
Masses and semi-major axis of planets at the end of formation
5000 planetary system - 1 planetary seed/system
0.1 1 10
Semi major axis [AU] 1e 01 1e+00 1e+01 1e+02 1e+03 1e+04
Mass [M ]0 0.2 0.4 0.6 0.8 1
Masses and semi-major axis of planets at the end of formation
500 planetary system - 10 planetary seeds/system
Q2 of ELSI: Why is water on Earth so little?
Number of planetary embryos
500 planetary system - 1/2/510/20/40 planetary seeds/system
Back to the Solar System
Walsh et al. 2011
gap merging
outward migration
resonant system
}
Time (Myr)
0 2 gap merging
outward migration
resonant system
}
Back to the Solar System
0
20%
40%
60%
80%
Saumon & Guillot, 2004; Helled et al. 2011; Leconte & Chabrier 2012
Jupiter Saturn Uranus Neptune
‘observations’
model Back to the Solar System
Conclusions
1- Considering the system is mandatory to
2- Testing our understanding requires
predict/explain terrestrial planet properties
both specialized and integrated models
Thank you!
ありがとうございました！
Mass (Earth masses)
Semi-major axis (AU)
Time
Mercury fr
action of icy planetesimals
Icy
Rocky
100 planetary systems - 10 planetary seeds/system
