Internal structures and compositions of (giant) exoplanets Tristan Guillot (OCA, Nice) Exoplanets in Lund Lund 6-8 May 2015
Linking interior & atmospheric composition Interior Atmosphere If(h clou low and 209 If(hot(Jupiter(atmospheres(are(assumed(to(be((
Linking interior & atmospheric composition 15 no core Radius / 10 9 cm 10 5 0 isolated no core H-He, no core 15 M core 100 100 M core 100 M core planets Teq=2000K T eq =1000K brown dwarfs stars 0.1 1.0 10.0 100.0 Mass / M Jup Interior Atmosphere If(h clou low and 209 Moutou et al. (2013) If(hot(Jupiter(atmospheres(are(assumed(to(be(( Madhusudhan et al. (2014)
Outline Jupiter & Saturn Theoretical considerations Giant exoplanets Perspectives
Jupiter & Saturn
Constraints on atmospheric composition
Interior compositions 165-170 K 1 bar Molecular H 2 (Y~0.23) 6300-6800 K 2 Mbar Helium rain 135-145 K 1 bar 15000-21000 K 40 Mbar Metallic H + (Y~0.27) Jupiter Ices + Rocks core? Molecular H 2 (Y~0.20?) Helium rain Metallic H + (Y~ 0.30?) Saturn 5850-6100 K 2 Mbar 8500-10000 K 10 Mbar
Interior compositions M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth
Interior compositions Fortney & Nettlemann (2010) M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth Helled & Guillot (2013)
Interior compositions M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth
Interior compositions M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth
Interior compositions M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth
Interior compositions M core /M Earth 30 25 20 15 10 5 0 Forbidden region "Slow" 1 Mbar 2 Mbar "Fast" 1 Mbar 2 Mbar atmospheric 3 Mbar atm + 8xSolar(H 2 O) 8xSolar(Z elements) 4 Mbar 0 2 4 6 8 10 M Z /M Earth
Theoretical considerations
The low-z content of accreted gas
The low-z content of accreted gas In standard core-accretion models, most of the heavy elements are accreted during the core growth phase. (A small fraction is accreted during the envelope collapse phase, when the increased gravitational reach brings a fresh supply of planetesimals). Pollack et al. (1996)
The low-z content of accreted gas In standard core-accretion models, most of the heavy elements are accreted during the core growth phase. (A small fraction is accreted during the envelope collapse phase, when the increased gravitational reach brings a fresh supply of planetesimals). With pebble accretion, pebbles are efficiently accreted until the planet reaches the pebble isolation mass (~20 MEarth). The rest of the accretion then most of the heavy elements are accreted during the core growth phase. (A small fraction is accreted during the envelope collapse phase, when the increased gravitational reach brings a fresh supply of planetesimals). (see Lambrechts et al. 2014) Log (Mprotoplanet) [MEarth] 2 0-2 -4 Pollack et al. (1996) -6-4 -2 0 2 4 Log(Dust size) [cm] 1.0 1.0 0.1 0.1 1.0 10.0 Guillot et al. (2014) 30 10 5 3 1 0.5 0.3 0.1 r Xfilter=1 [AU]
The low-z content of accreted gas In standard core-accretion models, most of the heavy elements are accreted during the core growth phase. (A small fraction is accreted during the envelope collapse phase, when the increased gravitational reach brings a fresh supply of planetesimals). With pebble accretion, pebbles are efficiently accreted until the planet reaches the pebble isolation mass (~20 MEarth). The rest of the accretion then most of the heavy elements are accreted during the core growth phase. (A small fraction is accreted during the envelope collapse phase, when the increased gravitational reach brings a fresh supply of planetesimals). (see Lambrechts et al. 2014) Once the planet is formed, the efficiency of planetesimal capture drops (e.g., Guillot & Gladman 2000, Matter et al. 2009) Log (Mprotoplanet) [MEarth] 2 0-2 -4 Pollack et al. (1996) -6-4 -2 0 2 4 Log(Dust size) [cm] 1.0 1.0 0.1 0.1 1.0 10.0 Guillot et al. (2014) 30 10 5 3 1 0.5 0.3 0.1 r Xfilter=1 [AU]
Enrichment of the envelopes Core accretion: planetesimals are delivered onto the central core. Core accretion: planetesimals cannot reach the core intact. (Podolak et al. 1988; Pollack et al. 1996) Envelope capture: accretion efficiency drops (Guillot & Gladman 2000): core erosion? Present: enriched atmospheres.
Core erosion A 5-20 MEarth core is expected for Jupiter, Saturn, Uranus and Neptune from formation models (see e.g. Mizuno 1980, Ikoma et al. 2001) Is the energy required to erode a primodial core available?
Core erosion A 5-20 MEarth core is expected for Jupiter, Saturn, Uranus and Neptune from formation models (see e.g. Mizuno 1980, Ikoma et al. 2001) Is the energy required to erode a primodial core available? Energy required to mix the core upward:
Core erosion A 5-20 MEarth core is expected for Jupiter, Saturn, Uranus and Neptune from formation models (see e.g. Mizuno 1980, Ikoma et al. 2001) Is the energy required to erode a primodial core available? Energy required to mix the core upward: Maximal core mass flux given intrinsic luminosity L 1 (t): ϖ 3/10 χ 0.1: assumes that 10% of the energy in the first convective cell is used to mix chemical elements
Core erosion A 5-20 MEarth core is expected for Jupiter, Saturn, Uranus and Neptune from formation models (see e.g. Mizuno 1980, Ikoma et al. 2001) Is the energy required to erode a primodial core available? Energy required to mix the core upward: Maximal core mass flux given intrinsic luminosity L 1 (t): Jupiter Saturn ϖ 3/10 χ 0.1: assumes that 10% of the energy in the first convective cell is used to mix chemical elements Guillot, Stevenson, Hubbard & Saumon (2004)
Core erosion Are elements in the core miscible with metallic hydrogen?
Core erosion Are elements in the core miscible with metallic hydrogen? Water Wilson & Militzer (2011)
Core erosion Are elements in the core miscible with metallic hydrogen? Water Silicates Wilson & Militzer (2011) Wilson & Militzer (2012)
Core erosion Are elements in the core miscible with metallic hydrogen? Water Silicates Wilson & Militzer (2011) Wilson & Militzer (2012) Core erosion is possible because the elements involved are miscible in metallic hydrogen
The noble gases (+N2) Delivered with ices as clathrates PH 3-5.67H 2 O Xe-5.75H 2 O Thermodynamic path of the Solar nebula between 5 and 20 AU Kr Ar
The noble gases (+N2) Delivered with ices as clathrates Gautier et al. (2001), Alibert et al. (2005), Mousis et al. (2009) PH 3-5.67H 2 O Xe-5.75H 2 O Thermodynamic path of the Solar nebula between 5 and 20 AU Kr Ar Guillot & Hueso (2006)
The noble gases (+N2) Delivered with ices as clathrates Gautier et al. (2001), Alibert et al. (2005), Mousis et al. (2009) or PH 3-5.67H 2 O Xe-5.75H 2 O Kr Thermodynamic path of the Solar nebula between 5 and 20 AU Ar Guillot & Hueso (2006)
The noble gases (+N2) Delivered with ices as clathrates Gautier et al. (2001), Alibert et al. (2005), Mousis et al. (2009) PH 3-5.67H 2 O Xe-5.75H 2 O Thermodynamic path of the Solar nebula between 5 and 20 AU or Kr Ar Disk enriched by H-He photoevaporation Guillot & Hueso (2006) see also Throop & Bally (2010) 1 2 3 4 H-He photoevaporation 3a T~10,000K 4 T~100K Low-temperature grains capture gases and settle to the disk mid-plane. Grains migrate in. Some volatiles may be released, but they do not reach the higher altitudes of the disk due to the negative temperature gradient there. The upper atmosphere of the disk evaporates due to radiation from the parent star (3a) and from external radiations (3b). This upper atmosphere contains moslty hydrogen and helium. Giant protoplanets gradually capture a disk gas which is enriched in non-hydrogen-helium species. 2 H-He photoevaporation 3b T~50~600K 1 T~10-30K
Interior vs. Atmosphere
Giant exoplanets
Mass-Radius diagram 30 0.60 25 [Fe/H] 0.00 Radius [R Earth ] 20 15 10 Transit Rad Vel Imaging -0.60 3.0 5 0 2013.09.30 1 10 10 2 10 3 10 4 Mass [M Earth ] M * [M Sun ] 1.0 0.3
Examples of bulk composition determination
Examples of bulk composition determination Models by M. Havel using CESAM CoRoT-20b CoRoT-17b Deleuil et al. (2012) CoRoT-27b Csizmadia et al. (2011) Parvainen et al. (2014)
Heavily irradiated planets & missing physics CoRoT-11b Gandolfi et al. (2010)
Heavily irradiated planets & missing physics CoRoT-11b Missing physics Gandolfi et al. (2010)
Heavily irradiated planets & missing physics CoRoT-11b Missing physics magnitude frequency a dependence [Fe/H] dependence age dependence Refs interior/atmosphere opacities ~ yes weak Guillot et al. (2006), Burrows et al. (2007), Guillot(2008) Semi-convection? X yes weak Chabrier & Baraffe (2007) K.E. model no no Gandolfi et al. (2010) Ohmic dissipation yes no/yes Thermal tides no no Obliquity tides? X no weak Eccentricity tides? no strong Guillot & Showman (2002), Burkert et al. (2005), Guillot et al. (2006, 2008) Laine et al. (2009), Batygin & Stevenson (2010) Arras & Socrates (2010), [but see Gu & Ogilvie (2009), Goodman (astroph)] Winn & Holman (2005), Levrard et al. (2006), Fabrycky et al. (2006) Bodenheimer et al. (2001), Gu et al. (2003), Jackson et al. (2008a,b), Ibgui & Burrows (2009), Miller et al. (2009)
Mass of heavy elements vs. stellar [Fe/H]
Mass of heavy elements vs. stellar [Fe/H] Guillot et al. (2006), Burrows et al. (2007), Guillot (2008), Miller & Fortney (2012), Moutou et al. (2013)
The importance of the radiative zone
The importance of the radiative zone Guillot & Showman (2002)
The importance of the radiative zone Can upward mixing persist in the radiative zone? Guillot & Showman (2002)
The importance of the radiative zone Can upward mixing persist in the radiative zone? Parmentier et al. (2013) Kzz~5x10 8 /Pbar cm 2 /s Guillot & Showman (2002)
The importance of the radiative zone Can upward mixing persist in the radiative zone? Parmentier et al. (2013) Kzz~5x10 8 /Pbar cm 2 /s Guillot & Showman (2002) tmix~ Hp δrp / Kzz ~10 Pbar Myr
The importance of the radiative zone Can upward mixing persist in the radiative zone? Parmentier et al. (2013) Kzz~5x10 8 /Pbar cm 2 /s Guillot & Showman (2002) tmix~ Hp δrp / Kzz ~10 Pbar Myr Mixing is prevented when radiative zone reaches the ~1kbar level! Rough estimate! Jupiter Saturn
Possible scenario
Possible scenario Hot Jupiters
Possible scenario Hot Jupiters Gentle accretion
Possible scenario Hot Jupiters Gentle accretion Low atmospheric abundance No correlation atmosphere/ interior
Possible scenario Hot Jupiters Gentle accretion Low atmospheric abundance No correlation atmosphere/ interior Giant impacts Moderate to high atmospheric abundance correlation atmosphere/ interior
Possible scenario Hot Jupiters Warm Jupiters Gentle accretion Low atmospheric abundance No correlation atmosphere/ interior Giant impacts Moderate to high atmospheric abundance correlation atmosphere/ interior correlation atmosphere/ interior
Perspectives
Perspectives Test formation models by comparing atmospheric abundances of known planets to bulk composition. CHEOPS, TESS PLATO Juno
Juno project overview Spacecraft: Spinning, polar orbiter spacecraft launches in August 2011 5-year cruise to Jupiter, JOI in July 2016 1 year operations, EOM via de-orbit into Jupiter in 2017 Elliptical 11-day orbit swings below radiation belts to minimize radiation exposure 2 nd mission in NASA s New Frontiers Program First solar-powered mission to Jupiter Payload of eight science instruments to conduct gravity, magnetic and atmospheric investigations, plus a camera for E/PO Science Objective: Improve our understanding of giant planet formation and evolution by studying Jupiter s origin, interior structure, atmospheric composition and dynamics, and magnetosphere Principal Investigator: Dr. Scott Bolton Southwest Research Institute
Deep atmosphere & Interior structure zonal harmonic degree n Guillot et al. (2004) Kaspi et al. (2010)
Radiometry Radiometry probes deep into meteorological layer Determines and maps the water and ammonia abundances