The giant challenges in our understanding of giant planet internal - - PowerPoint PPT Presentation

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The giant challenges in our understanding of giant planet internal - - PowerPoint PPT Presentation

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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 )

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

The giant challenges in our understanding

  • f 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 Jupiter & Saturn: EOS, standard models, new approaches Uranus & Neptune: ices and ice-rich models

Republic of Kasakhstan UCSC Keck NASA Cassini / NASA

  • M. French / VASP

Sun

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

1-100 bar , ~100-1000 K

  • mostly H-He

M-R

  • high pressures ( < ~100 Mbar)

M-R

  • warm (~10 000 K)

luminosity, formation theory

  • non-ideal, dense matter,

conducting , H+, e-, ionized C,N,O

plasma / conducting, convective, adiabatic

fluid, mostly H2 , convective, adiabatic ~1 Mbar, few 1000 K ~5 - 50 Mbar, ~5 - 150,000 K

Introduction

<100 Mbar transition region

2 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

1-100 bar , ~100-1000 K ~1 Mbar, few 1000 K ~5 - 50 Mbar, ~5 - 150,000 K

Introduction

<100 Mbar what do we mean by “internal structure“ ?

  • composition (e.g. bulk water content, bulk

rock content)

  • size and number of chemically

distinct layers (e.g. core)

what do we want to know, and why ?

  • core mass -> formation (!?!)
  • bulk enrichment -> formation
  • atmospheric energy balance ->

fundamental science

  • magnetic dynamo operation -> fundamental

science

fluid, mostly H2 , convective, adiabatic transition region

plasma / conducting, convective, adiabatic 3 / 37

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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

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

EGP structure: general assumptions

ad

∇

  • 2 Layer (core + envelope)
  • adiabatic interior
  • radiative atmosphere (BC)
  • hydrostatic equilibrium

a t m

  • s

p h e r e 5 / 37

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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

  • utput:

internal Temperature – Pressure – Density profile input: (i) entropy (ii) EOS of single components, (ii) composition LOW-MASS STARS / BROWN DWARFS thermal convection because of high opacity adiabatic EARTH: thermal convection + thermal diffiusion (Fe) core -- (Mg,Si,O) mantle boundary: magnetic field

T ad

( ) ∇ > ∇

5 T ad

( ~10 )

−

∇ −∇

T ad

( ) ∇ ∇

  • T

ad

( ) ∇ = ∇

T (

, , , ,..., )

tot T

F κ γ η κ ∇

log T log d T d P

∇ ≡

6 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

atmosphere (boundary condition)

  • utput:

entropy s input: inbound heat flow Teq (Tstar, obital a) ;

  • utbound heat flow Teff ;

model atmosphere (composition, opacities, Teff, ...)

9.5 AU (Saturn) 0.1 AU atmospheric Pressure – Temperature profiles

hot / young / weakly irradiated cold / old / strongly irradiated ➢ Fortney, Marley, Barnes 2007

7 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

general assumptions : 2-Layer structure

He H O , C , N , S i , M g rocks, ices

adiabatic, convective, homogeneous

Free parameters:

  • core mass (Mcore)
  • envelope Z (Zenv)
  • composition of Z-material (Zi)

8 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

hydrostatic equilibrium

Boundary Conditions: (i) P(M) ~ 0 , (ii) r(0) = 0 input: P-ρ- relation , i.e. EOSs & composition { Mcore, Zenv, Zi }

  • utput:

R(M) for given ρ(P) -> M-R relations alternative output: bulk Z, i.e. one of { Mcore, Zenv, Zi } for given R(M)

4

4 dP Gm dm r π = −

2 1

(4 ) dr r dm π ρ − =

0....

p

m M =

9 / 37

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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

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

M-R relations for given compositions

➢ Fortney, Marley, Barnes 2007

  • Zenv = 0
  • Zice = Zrocks = 0.5
  • Mcore = 10...100 MEarth

11 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

EGP composition estimates for observed Mp-Rp

weakly irradiated (Miller &Fortney 2011) (Guillot 2006) (Maciejewski et al 2011) (Deleuil et al 2011) perhaps brown dwarfs (Leconte, Baraffe, Chabrier 2009) Jup

12 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

results for Mz, Zp for weakly irradiated planets

➢ Miller & Fortney 2011

MZ ~ 10 ME, Zp ~ 2-10x Zstar

Zplanet / Zstar Mz / MEarth

Z p planet

M Z M =

? ?

13 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Tidal Love number k2 breaks the degeneracy

Given: Mp , Rp , . + temperature profile and atmospheric boundary condition The total heavy element content can be determined, but not the core mass or envelope enrichment . Given: Mp , Rp , and the Love number k2 . + temperature profile and atmospheric bounday condition Assuming a 2L structure, both Mcore and Zenv can be determined. H H H He

core envelope metallicity

He He

➢ Kramm et al. (2011), A&A

14 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

➢ Kramm, Nettelmann, Fortney et al 2012 ➢ Batygin et al 2009 ➢ Winn et al 2010

Mp = 0.85 MJ , Rp = 1.3 RJ , and also k2 = 0.27-0.38

HAT-P-13b model, similar to Jupiter H He m e t a l s

HAT-P13b, the only planet with inferred k2

15 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Observable Solar GP Extrasolar GP

Mass Mp 14.5 – 318 MEarth RV & Transit Radius Rp equatorial radius Req mean R (Transit) Pressure P (Rp) 1 bar 1 mbar T (Rp) 70 - 170 K 500 - 2000 K mean helium mass fraction Y 0.27 (solar) 0.25 - 0.28 atmospheric He mass fraction Y1 0.27 Y1 = Y atmospheric metallicity Z1 2 x solar spectroscopy period of rotation ω 9 – 17 h

ω orbital period (days)

gravitational moments J2n J2, J4, J6

  • Love number k2
  • k2 (e, TTV )

age 4.56 Gyr 0.3 – 10 Gyr Teff 60 - 120 K secondary eclipse / imaging

≤

≈

≥

Observational constraints

  • bservational constraints

16 / 37

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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

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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

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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

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Jupiter standard models

Yatm=0.238 h e l i u m hydrogen

Zouter = Zinner(J2)

➢ Saumon & Guillot 2004 ➢ Militzer, Hubbard et al . 2008 (Y=0.238)

Zouter(J4), Zinner(J2)

➢ Chabrier et al 1992 ➢ Guillot 1999 ➢ Nettelmann et al 2008,2012, . Becker et al 2014 1-10 Mbar, 6-11 000 K ~40 Mbar, 17-21 000 K T1bar=165-170 K OCNSP...

spacetelescope.org

20 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Core mass and outer envelope metallicity

  • f Jupiter models with different EOS

Ab initio LM-REOS.2 gives Jupiter models in agreement with the measured noble gas abundances, while SCvHi and Sesame EOS support the values of N,C.

SCvHi Sesame LM-REOS heavy element abundance (solar units) in the outer envelope

The maximum core mass is predicted to be 3 ME (Sesame), 5 ME (SCvHi), and 8 ME (LM-REOS). P1-2

➢ Atreya et al. 2003, PSS ➢ Lodders 2003, ApJ ➢ Saumon & Guillot (2004), ApJ ➢ Fortney & Nettelmann (2010) 21 / 37

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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 4--7 < 4.5

LM-REOS.2 SCvHi EOS Sesame EOS

  • uter

envelope metallicity (solar units)

NASA

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challenge: Jupiter‘s atmospheric helium depletion

Observed He depletion suggests helium rain.

23 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

challenge: SATURN’s excess luminosity

Jupiter: standard models reproduce all observational constraints Saturn: standard models predict too low luminosity

7 / 32 24 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

challenge: SATURN‘s dipolar magnetic field

➢ Stevenson 1980, 1982 ➢ Cao, Russell, Christensen et al 2011 ➢ Cao, Russell, Wicht et al 2012 H2, He poorly conducting convective H/He demixing zone?

(gradual He concentration? stably stratified? differentially rotating ? filtering of non-dipolar components?)

H+, He rain dynamo-generation of mag. field

(convective, metallic)

core

Saturn‘s magnetic field is highly axis-symmetric. A thick stable, and/or differentially rotating region can axisymmetrize the B-field. Such a region may result from H/He demixing or core erosion.

1 Mbar, ~ 5000 K

H+, He

Cassini / NASA

www.lasp.colorado.edu/~bagenal/

< 1°

Magnetic axis Rotation axis

25 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Inhomogeneous & Superadiabatic interior with layered instead of overturning convection?

➢ Leconte & Chabrier 2012, A&A

µ

An inhomogeneous, superadiabatic planet may be ~50% more enriched in heavy elements.

26 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Semi-convection can dramatically change the cooling behavior. Figures show L(t) for different mixing lengths of layered-convection.

1 MJup, Z-gradient (Vazan et al 2015) 1 MSat, Z-gradient (Leconte & Chabrier 2013) 1 MJup, He-gradient (Nettelmann et al 2015) log L / Lsun log time (Gyr) time (Gyr) Teff (K) Teff (K) 27 / 37

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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: ices and ice-rich models for Uranus

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models Voyager 2 flyby 1986 Voyager 2 flyby 1989

Uranus Neptune

  • Mass: 14.5 M , Radius: 4 R
  • mean densitiy : 1.3 g/cm3
  • orbital distance : 19.2 AU
  • heat flow Teff ~ 59 K
  • irradiation Teq ~ 59 K

⊕ ⊕

  • Mass: 17 M , Radius: 3.9 R
  • mean densitiy : 1.7 g/cm3
  • orbital distance : 30 AU
  • Teff ~ 59 K
  • Teq ~ 46 K

⊕ ⊕

  • bservational constraints

EGPs:

  • GJ 436b
  • HAT-p 11b
  • Kepler 4b

Cassini/NASA Sun

29 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

phase diagrams

WATER

➢ Redmer et al 2010, Icarus ➢ Bethkenhagen, French, Redmer 2013. PRB

AMMONIA Superionic Dissociated

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

phase diagram of 1:1 water-ammonia mixture

➢ Bethkenhagen, Cebulla, Redmer, Hamel 2015

31 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Phase diagram of synthetic URANUS mixture

(H:O:C:N ~ 28:7:4:1)

➢ Chau, Hamel, Nellis 2011

Carbon clustering or superionic deep interior?

32 / 37

Experiments (gas-gun): reverberating shock

single shock

Theory: computer simulations

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Standard URANUS model with H2O-CH4-NH3 EOS

assumptions:

heavy elements = water, ammonia, methane rocks confined to core 3-layer structure, adiabatic

  • utstanding property:

icy lower mantle

achievements:

presence of magnetic dynamo, O/C/N = solar

less convincing:

ice/rock ratio ~ 15x solar too high luminosity (~too long cooling time)

molecular ionic super- ionic poly- mers molecular: H2O, N2, H2, CH4 molecules ➢ Betkenhagen et al, in prep ➢ Podolak & Reynolds 1987 33 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

challenge: Uranus‘ low luminosity

too long cooling time (too high luminosity) of adiabatic models, whatever one varies

➢ Hubbard & Marley 1980 ➢ Hubbard et al 1995 ➢ Fortney et al 2011 ➢ Nettelmann et al 2013 34 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Uranus: compositional and thermal layer boundary

(cm2/s) 4.5 Gyr If the layer boundary is diffusive, it‘ll stay stably stratified forever. This suggests presence of thermal boundary layer.

35 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

First Uranus model with (very simplified) thermal boundary can explain both the luminosity and the gravity data.

➢ Nettelmann, Wang, Fortney, Hamel et al, submitted

1

Teff (K)

L = Linc

Teq

36 / 37

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Summary

  • EGP: measured M-R allow to derive bulk mass of heavy elements.
  • EGP: internal structure models indicate MZ >= 10 ME.
  • Tidal Love number k2 may break the degeneracy.
  • Interior models usually applied to EGPs do not hold for the solar GPs.
  • Jupiter: O/H to be measured by Juno
  • layered-convection consistent with luminosity of Jupiter and Saturn
  • Uranus‘ may be ice-rock rich, without solid ices.
  • Outlook: construction of solar GP models that also are consistent with

the observed magnetic fields

Thank you for attention

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Appendix

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

H phase diagrams

21 / 41

Log Pressure (Mbar)

solid H2 solid H degenerate TCP classical TCP fluid H2 fluid H

  • 2
  • 4
  • 6

2 4 6 2 3 4 5 Log T (K)

Liquid-Liquid Transition (ab initio sims)

➢ McMahon et al (2012), Rev. Mod. Phys. ➢ Stevenson (1982), Ann. Rev. E&Planet Sci.

1 Mbar

Wigner & Huntington (1935): prediction of metallization of solid H at sufficiently high densities as ,

2/3

~

kin el

E ρ

1/3

~

ie el

E ρ −

Ebeling et al 1985 Saumon, Chabrier et al 1995 Schlanges, Bonitz et al 1995 Fortov et al 2007, quasi-isentropic compression

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Reflectivity signal inferred from Z-machine experiment

24 / 41

absorption at 532 nm deuterium transparent deuterium metallizes ➢ Knudson et al (2015), . Science

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Liquid-Liquid transition in D found at 3 Mbar using Sandia‘s Z-machine

25 / 41 PIMD ➢ PIMD: Morales et al 2013, PRL ➢ PBE: Lorenzen et al 2010, Morales et al 2010 ➢ vdw-DF2: Lee et al 2010 PBE DF1 NQE vdW- DF2 NQE HSE DF2

➢ Knudson et al (2015), . Science

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

simple thermal boundary layer model for Uranus

ΔT across layer boundary is varied with time (linear increase with T1bar) ΔT (today) is adjusted to yield the proper cooling tome (luminosity)

11 / 20

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

Brown dwarf radii, effect of H-He-REOS.3

  • H-He REOS.3 predicts

~2 % larger radii for brown dwarfs.

  • PLATO (launch 2024)

accuracy <2%

  • possible test of BD

composition ~ stellar composition ➢ Becker, Lorenzen, Fortney, Nettelmann, Schöttler, Redmer 2014, ApJS

➢ Saumon, Chabrier, van Horn (1995), ApJS ➢ PLATO: Rauer et al 2013 17 / 41

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OHP colloquium, Okt2015 N.Nettelmann @ U Rostock Internal structure models

weak irradiation : Firr < 150 FEarth

➢ Miller & Fortney 2011

13 / 38