Planet-disc interactions and the early orbital evolution of planetary systems
Clément Baruteau CNRS / IRAP, Toulouse
ISSI-Beijing Workshop “The disk in relation to the formation of planets and their protoatmospheres”
26 August 2014
Talk outline
□ Exoplanet statistics → disc migration of terrestrial planets
□ Misaligned hot Jupiters → high-eccentricity migration, tides
□ Close-in, compact multiplanet systems → in situ growth vs. disc migration
Talk outline
□ Exoplanet statistics → disc migration of terrestrial planets
□ Misaligned hot Jupiters → high-eccentricity migration, tides
□ Close-in, compact multiplanet systems → in situ growth vs. disc migration
Need to slow down the migration of terrestrial planets
Planet mass [Earth masses]
OBSERVATIONS
+ Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
wakes wakes
Planet mass [Earth masses]
star planet + Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
Planet mass [Earth masses]
inner wake wakes
rp + Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
torque due to inner wake ~ rp x Fφ > 0
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
Planet mass [Earth masses]
wakes
rp + Jupiter
outer wake
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
torque due to inner wake ~ rp x Fφ > 0 torque due to outer wake ~ rp x Fφ < 0
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
wakes
Planet mass [Earth masses]
Coorbital density perturbations
star planet
+ Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
wakes
Planet mass [Earth masses]
Coorbital density perturbations
star planet
+ Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Need to slow down the migration of terrestrial planets OBSERVATIONS
MODELS
Planet mass [Earth masses]
wakes
rp + Jupiter
+ Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
planet
Baruteau+ 2013 (chapter at Protostars & Planets VI)
Perturbed density of a disc with a 5 Earth-mass planet
Torque exerted by the disc on the planet: Г = dJp / dt with Jp = Mp(G M* rp)1/2 the orbital angular momentum of a planet on a circular orbit (rp= orbital radius) → d rp / dt ~ Г / Mp
Need to slow down the migration of terrestrial planets OBSERVATIONS
IMPROVING MODELS
□ disc radiative properties
Planet mass [Earth masses]
Baruteau & Masset 2008; Paardekooper & Papaloizou 2008, Masset & Casoli 2010; Paardekooper+ 2011, Bitsch+ 2013 ...
star + Jupiter planet + Earth
Semi-major axis [AU] Ida & Lin 2008; Mordasini+ 2009
POPULATION SYNTHESES (1D)
Super-Earth in a non-isothermal disc
Need to slow down the migration of terrestrial planets OBSERVATIONS
IMPROVING MODELS
□ disc radiative properties
Planet mass [Earth masses]
Baruteau & Masset 2008; Paardekooper & Papaloizou 2008, Masset & Casoli 2010; Paardekooper+ 2011, Bitsch+ 2013 ...
104
star
3
10
planet 10
2
10 0.1
1 Semi-major axis [AU]
10
Dittkrist+ 2014
POPULATION SYNTHESES (1D)
Super-Earth in a non-isothermal disc
Need to slow down the migration of terrestrial planets OBSERVATIONS
IMPROVING MODELS
□ disc radiative properties □ disc turbulence
Planet mass [Earth masses]
Nelson & Papaloizou 2004; Baruteau & Lin 2010; Baruteau+ 2011; Uribe+ 2011
104 103 star 102
planet
10 0.1
1 Semi-major axis [AU]
10
Dittkrist+ 2014
POPULATION SYNTHESES (1D)
Saturn-mass planet in a MRI-turbulent disc
Need to slow down the migration of terrestrial planets OBSERVATIONS
IMPROVING MODELS
□ disc radiative properties □ disc turbulence □ disc magnetic properties
Planet mass [Earth masses]
Terquem 2003; Fromang+ 2005; Muto+ 2008; Guilet+ 2013
104 103 102
star planet
10 0.1
1 Semi-major axis [AU]
10
Dittkrist+ 2014
POPULATION SYNTHESES (1D) Super-Earth in a disc with a toroidal B field
Need to slow down the migration of terrestrial planets OBSERVATIONS
IMPROVING MODELS
□ migration of terrestrial planets is very
Planet mass [Earth masses]
sensitive to discs physical properties
104 103 102
Bitsch+ 2013
10 0.1
1 Semi-major axis [AU]
10
Dittkrist+ 2014
POPULATION SYNTHESES (1D)
→ ALMA discs observations will (hopefully) help constrain migration models
Talk outline
□ Exoplanet statistics → disc migration of terrestrial planets
□ Misaligned hot Jupiters → high-eccentricity migration, tides
□ Close-in, compact multiplanet systems → in situ growth vs. disc migration
Hot Jupiters' obliquities: constraints on migration scenarios?
Schlaufman 2010
□ Rossiter-MacLaughlin effect e.g., Winn+ 2005
□ Planet-starspot crossings
lin e
of
si gh t
e.g., Sanchis-Ojeda+ 2011
λ : projected obliquity n : star's spin axis s
n : planet's orbital axis p
ψ = acos(n .n ) : true obliquity s
p
□ Constraining true obliquity (ψ) with stellar spin axis angle (is) e.g., Huber+ 2013, Chaplin+ 2013
Hot Jupiters' obliquities: constraints on migration scenarios? OBSERVATIONS
data extracted from exoplanets.org (06/2014)
□ (Why) do hot Jupiters around hot stars tend to have high obliquities?
Hot Jupiters' obliquities: constraints on migration scenarios? OBSERVATIONS
MODELS □ Disc migration is a natural source of aligned hot Jupiters → disc misaligned by nearby stars? Bate+ 2010, Batygin 2012
→ tidal flip of stellar axis? Cebron+ 2013, Barker & Lithwick 2014 55 Cnc e Bouvier & Hébrard 14
data extracted from exoplanets.org (06/2014)
□ (Why) do hot Jupiters around hot stars tend to have high obliquities?
Hot Jupiters' obliquities: constraints on migration scenarios? OBSERVATIONS
MODELS □ Disc migration is a natural source of aligned hot Jupiters → disc misaligned by nearby stars? Bate+ 2010, Batygin 2012
→ tidal flip of stellar axis? Cebron+ 2013, Barker & Lithwick 2014
□ High-eccentricity migration followed by tidal circularization is a natural source of misaligned hot Jupiters → can all hot Jupiters form this way? data extracted from exoplanets.org (06/2014)
□ (Why) do hot Jupiters around hot stars tend to have high obliquities?
Triaud+ 2010, Albrecht + 2012, but see Rogers & Lin 2013, Lai 2012
Hot Jupiters' obliquities: constraints on migration scenarios? □ Disc misaligned by nearby stars
□ High-eccentricity migration + tides
Crida & Batygin 2014
Hot Jupiters' obliquities: constraints on migration scenarios? □ Disc misaligned by nearby stars
□ High-eccentricity migration + tides
Crida & Batygin 2014
→ disc migration needed to account for number of aligned hot Jupiters. → observations cannot (yet) distinguish between misalignement mechanisms
Talk outline
□ Exoplanet statistics → disc migration of terrestrial planets
□ Misaligned hot Jupiters → high-eccentricity migration, tides
□ Close-in, compact multiplanet systems → in situ growth vs. disc migration
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
data extracted from exoplanets.org (06/2014)
□ Many planet pairs are not in resonance, but those near resonances tend to have period ratios slightly greater than resonant
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 171 planets in 68 systems 66% of 2 planets, 23% of 3, 11% of 4 and more
data extracted from exoplanets.org (06/2014)
□ Same trend for RV-detected multiple systems near the 2:1 resonance?
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
data extracted from exoplanets.org (06/2014)
□ Unseen companions? Steffen 2013
5:4 ?
3:2
3/2 x 5/4 = 1.875!
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
MODELS □ In-situ growth of planet embryos Hansen & Murray 2013; see also Raymond & Cossou 2014
data extracted from exoplanets.org (06/2014)
□ Many planet pairs are not in resonance, but those near resonances tend to have period ratios slightly greater than resonant
Hansen & Murray 2013
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
MODELS □ In-situ growth of planet embryos □ Tidal dissipation of close-in resonant planetary systems Papaloizou 2011, Lithwick & Wu 2012, ...
data extracted from exoplanets.org (06/2014)
□ Many planet pairs are not in resonance, but those near resonances tend to have period ratios slightly greater than resonant
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
MODELS □ In-situ growth of planet embryos □ Tidal dissipation of close-in resonant planetary systems Papaloizou 2011, Lithwick & Wu 2012, ...
data extracted from exoplanets.org (06/2014)
□ Many planet pairs are not in resonance, but those near resonances tend to have period ratios slightly greater than resonant
Architecture of Kepler's confirmed multiplanet systems OBSERVATIONS → 836 planets in 335 systems 66% of 2 planets, 22% of 3, 12% of 4 and more
MODELS □ In-situ growth of planet embryos □ Tidal dissipation of close-in resonant planetary systems □ Disc-migration of partial gapopening planets Baruteau & Papaloizou 2013
data extracted from exoplanets.org (06/2014)
□ Many planet pairs are not in resonance, but those near resonances tend to have period ratios slightly greater than resonant
How important are planet-disc interactions in shaping exoplanetary systems? □ Disc migration is inevitable! → diversity of outcomes linked to expected variety in disc structures
□ Many mechanisms contribute to the orbital evolution of planetary systems → disc and high-eccentricity migrations, interactions with host and nearby stars all play some role
□ More observations to constrain migration models → CHEOPS, TESS, SPIRou, ESPRESSO, SPHERE, PLATO, ...
ISSI-Beijing Workshop
26 August 2014
