The giant challenges in our understanding of giant planet internal structures Nadine Nettelmann (U Rostock) acknowledgements: R. Redmer, M. French, M. Bethkenhagen, A. Becker ( U Rostock ), J.J. Fortney, ( UCSC ), S. Hamel ( LLNL ) Introduction Method of GP internal structure modeling EGPs: M-R relations & composition estimates Keck Jupiter & Saturn: EOS, standard models, new approaches Sun Uranus & Neptune: ices and ice-rich models M. French / VASP Republic of Kasakhstan Cassini / NASA NASA UCSC OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Introduction 1-100 bar , ~100-1000 K • mostly H-He fluid, mostly H 2 , M-R convective, adiabatic • high pressures ( < ~100 Mbar) M-R • warm (~10 000 K) transition region luminosity, formation theory ~1 Mbar, few 1000 K • non-ideal, dense matter, plasma / conducting, conducting , H + , e - , ionized C,N,O convective, adiabatic ~5 - 50 Mbar, ~5 - 150,000 K <100 Mbar 2 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Introduction what do we mean by “internal structure“ ? 1-100 bar , ~100-1000 K • composition (e.g. bulk water content, bulk rock content) fluid, mostly H 2 , convective, adiabatic • size and number of chemically distinct layers (e.g. core) what do we want to know, and why ? transition region • core mass -> formation (!?!) ~1 Mbar, • bulk enrichment -> formation few 1000 K • atmospheric energy balance -> plasma / conducting, fundamental science convective, adiabatic • magnetic dynamo operation -> fundamental science ~5 - 50 Mbar, ~5 - 150,000 K <100 Mbar 3 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Outline Method of EGP internal structure modeling EGPs: M-R relations & composition estimates Jupiter & Saturn Uranus & Neptune OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
EGP structure: general assumptions s p h o e a t m r • 2 Layer (core + envelope) e • adiabatic interior ∇ ad • radiative atmosphere (BC) • hydrostatic equilibrium 5 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
general assumptions : adiabatic interior 2D EOS { T, P, ρ (T, P), s(T,P) } -> 1D path { T(P) s , ρ (P) s } at constant entropy s d log T ∇ ≡ T d log P LOW-MASS STARS / BROWN DWARFS 5 ( ~10 ) − thermal convection because of high opacity ∇ −∇ T ad ( ) adiabatic ∇ = ∇ T ad EARTH: thermal convection + thermal diffiusion ( ) ∇ > ∇ T ad T ( F , , , ,..., ) ∇ κ γ η κ tot T (Fe) core -- (Mg,Si,O) mantle boundary: magnetic field ( ) � ∇ ∇ T ad output: internal Temperature – Pressure – Density profile input: (i) entropy (ii) EOS of single components, (ii) composition 6 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
atmosphere (boundary condition) output: entropy s input: inbound heat flow T eq (T star , obital a) ; outbound heat flow T eff ; model atmosphere (composition, opacities, T eff , ...) atmospheric Pressure – Temperature profiles 0.1 AU 9.5 AU hot / young / (Saturn) weakly irradiated cold / old / strongly irradiated ➢ Fortney, Marley, Barnes 2007 7 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
general assumptions : 2-Layer structure C , O H He , N , , i S g M adiabatic, Free parameters: convective, homogeneous • core mass (M core ) • envelope Z (Z env ) • composition of Z-material (Z i ) rocks, ices 8 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
hydrostatic equilibrium dP Gm = − 4 dm 4 r π m 0.... M = p dr 2 1 (4 r ) ρ − = π dm Boundary Conditions: (i) P(M) ~ 0 , (ii) r(0) = 0 input: P- ρ - relation , i.e. EOSs & composition { M core , Z env , Z i } output: R(M) for given ρ (P) -> M-R relations alternative output: bulk Z, i.e. one of { M core , Z env , Z i } for given R(M) 9 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Outline Method of GP internal structure modeling EGPs : M-R relations & composition estimates Jupiter & Saturn Uranus & Neptune OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
M-R relations for given compositions • Z env = 0 • Z ice = Z rocks = 0.5 • M core = 10...100 M Earth ➢ Fortney, Marley, Barnes 2007 11 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
EGP composition estimates for observed M p -R p weakly irradiated (Miller &Fortney 2011) (Guillot 2006) (Maciejewski et al 2011) (Deleuil et al 2011) perhaps brown dwarfs Jup (Leconte, Baraffe, Chabrier 2009) 12 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
results for M z , Z p for weakly irradiated planets M Z ~ 10 M E , Z p ~ 2-10x Z star M z / M Earth ? M Z planet / Z star Z Z = p M planet ? ➢ Miller & Fortney 2011 13 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Tidal Love number k 2 breaks the degeneracy Given: M p , R p , . + temperature profile and atmospheric boundary condition The total heavy element content can be determined, but not the core mass or envelope enrichment . He H H He envelope metallicity core Given: M p , R p , and the Love number k 2 . + temperature profile and atmospheric bounday condition Assuming a 2L structure, He H both M core and Z env can be determined. ➢ Kramm et al. (2011), A&A 14 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
HAT-P13b, the only planet with inferred k 2 M p = 0.85 M J , R p = 1.3 R J , and also k 2 = 0.27-0.38 HAT-P-13b model, similar to Jupiter e t m a He l H s ➢ Kramm, Nettelmann, Fortney et al 2012 ➢ Batygin et al 2009 ➢ Winn et al 2010 15 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Observational constraints observational constraints Observable Solar GP Extrasolar GP Mass M p 14.5 – 318 M Earth RV & Transit Radius R p equatorial radius R eq mean R (Transit) Pressure P (R p ) 1 bar 1 mbar T (R p ) 70 - 170 K 500 - 2000 K mean helium mass fraction Y 0.27 (solar) 0.25 - 0.28 atmospheric He mass fraction Y 1 0.27 Y 1 = Y ≤ atmospheric metallicity Z 1 ≥ 2 x solar spectroscopy period of rotation ω ω orbital period (days) ≈ 9 – 17 h gravitational moments J 2n J 2 , J 4 , J 6 - Love number k 2 - k 2 (e, TTV ) age 4.56 Gyr 0.3 – 10 Gyr T eff 60 - 120 K secondary eclipse / imaging 16 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Outline Method of GP internal structure modeling EGPs: M-R relations & composition estimates Jupiter & Saturn EOS, standard models, new approaches Uranus & Neptune OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
EOS from simulations in comparison with experiments DEUTERIUM [1,2] quasi-isentropic and isothermal compression WATER [3] single & double shock compression M. French / VASP [1] Becker et al 2013 [2] Loubeyre et al 2007 [3] Knudson et al 2012 18 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Single shock experiments to probe the H EOS The different H EOS are stiff/compressible at individual pressure levels. Sesame: chem. picture ➢ Los Alamos database SCvHi: chem. picture ➢ Saumon et al. (1995), ApJS H-REOS: simulations ➢ Holst et al. (2008), PRB Experiments: ➢ Knudson & Desjarlais (2009) ➢ Boriskov et al. (2005) ➢ Knudson et al. (2004), PRB ➢ Nellis et al (1983) 19 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Jupiter standard models spacetelescope.org Z outer = Z inner (J 2 ) T 1bar =165-170 K ➢ Saumon & Guillot 2004 hydrogen Y atm =0.238 ➢ Militzer, Hubbard et al . 2008 (Y=0.238) OCNSP... 1-10 Mbar, 6-11 000 K m u i l e h Z outer (J 4 ), Z inner (J 2 ) ➢ Chabrier et al 1992 ➢ Guillot 1999 ~40 Mbar, 17-21 000 K ➢ Nettelmann et al 2008,2012, . Becker et al 2014 20 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Core mass and outer envelope metallicity of Jupiter models with different EOS The maximum core mass is predicted to be 3 M E (Sesame), 5 M E (SCvHi), and 8 M E (LM-REOS). LM-REOS SCvHi Sesame Ab initio LM-REOS.2 gives Jupiter models in agreement with the measured noble gas abundances, heavy while SCvHi and Sesame EOS element abundance support the values of N,C. (solar units) in the outer envelope ➢ Atreya et al. 2003, PSS ➢ Lodders 2003, ApJ ➢ Saumon & Guillot (2004), ApJ P 1-2 ➢ Fortney & Nettelmann (2010) 21 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
Expected O/H measurement by Juno (2016) A discrimination of the competing Jupiter models (and EOS) is in reach if the O:H abundance will be measured by Juno. 3--12x solar SCvHi EOS outer envelope metallicity 4--7 Sesame EOS (solar units) < 4.5 NASA LM-REOS.2 22 / 37 OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models
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