ドップラー振動撮像装置を用いた

木星自由振動観測
内部構造と起源の解明に向けて

生駒 大洋
東京大学大学院理学系研究科

共同研究者：佐藤文衛，井田茂 (東工大)，T. Guillot (OCA)
JOVIAL チーム

木星内部構造
T. Guillot & D. Gautier / Treatise on Geophysics, 2nd Edition 00 (2014) 1–42

17

Phase Diagram of Hydrogen &T-P profile in Jupiter’s envelope
T=TP ga

6b5+HmplasaRo

Co

29l2

HD2

lar3uolec

H2 m

epNs,nua
Ur2iter
Jup rntu
Saetunlidic
H atom 8 b0945

lic-202letamlidsoIVIgas uidIImolecularliq1BG+4H+ metallic

15T-Hsolog
log T T[K][K]H2 molecular

F=P rsnSu

composed of H & He

and a small fraction of heavy elements

ad7

EnvelopeCore?
III468log P [bar]composed of “heavy elements”

metallic

10

that were present in a proto-solar disk

12

in the form of ice and rocklog P [bar]Figure 5. Phase diagram for hydrogen in the pressure-temperature plane, with pressure in bars (1 bar = 105 Pa = 106 dyn cm−2 ). The thick lines
indicate the first order (discontinuous) phase transitions, the black circles the critical points (McMahon et al., 2012; Morales et al., 2013b). Phasetransitions in solid hydrogen with the diﬀerent known phases are labelled I, II, III, IV (McMahon et al., 2012). The region where 50% of allhydrogen is in atomic form (from Saumon et al., 1995) is shown by a thin contour. The approximate location of the molecular to metallic hydrogen

Figure from Guillot & Gautier (2014)

木星内部の不明な点
中心に高密度コアは存在するのか？その大きさは？
コアとエンベロープに明確な境界は存在するのか？

Envelope

composed of H & Heand a small fraction of heavy elements

H2 molecularH+ metallic

エンベロープに重元素はどの程度含まれているのか？また, 分布は一様なのか？
分子/金属水素層境界の深さは？
また, 遷移は不連続なのか？
水素とヘリウムの分布に偏りはあるのか？

Core

composed of “heavy elements”
that were present in a proto-solar disk

in the form of ice and rock従来の内部構造の推定法
重力ポテンシャル
=

観測

GM
1r

Rer

n=12nJ2n P2n (cos )重力モーメント
12n 1 + 1)1/2RJanuary
The Astrophysical Journal, 726:15 (7pp),M2011
e (4nJ2n =Jupiter

4Contribution functions

J4J22and Neptune that fit their measured gravitational fields aderived using Monte Carlo searches (Marley et al. 1995; Podolet al. 2000). This approach is free of preconceived notions abo
planetary structure and composition and is not limited by t
EOSs of assumed materials. Once the density profiles that fit t
gravitational coefficients are found, conclusions regarding thpossible compositions can be inferred using theoretical EO(Marley et al. 1995).
In this paper, we apply the method previously used in omodels of Saturn (Anderson & Schubert 2007; Helled et2009a) to derive continuous radial density and pressure profithat fit the mass, radius, and gravitational moments of Uranand Neptune. The use of a smooth function for the denswith no discontinuities allows us to test whether Uranus a
Neptune could have interiors with no density (and compositiodiscontinuities. Section 2 summarizes the models and results.

エンベロープの浅い部分の構造に敏感で, 深部の情報は取れない

J01
core00.0

Helled et

重力モーメントと整合的な内部密度分布を理論的に決定する

J63P2n (cos )r2n (r)d3 r

超高圧の物性に大きく依存する
0.20.4
0.6
Normalized Mean Radius βNeptune

0.81.0従来の内部構造の推定法：コア質量J.J. Fortney, N. Nettelmannsfe%
ed27,yeZ2 )ng

コア質量 [地球質量=1]

ofREOS-3

Equation of state fromab initio calculations

Fortney & Nettelmann (2010, SSRv)

エンベロープに含める重元素の総質量 [地球質量=1]

コア質量に大きな不定性あり
エンベロープに含まれる重元素量にも大きな不定性

木星型惑星形成モデル
Ikoma, Nakazawa & Emori (2000, ApJ)

100

二段階集積

801) 微惑星の集積によってコアが成長し、臨界コ収縮によるエネルギー供給

6040

微惑星によるエネルギー供給

200

ア質量に到達する

エンベロープ質量 [Earth=1]

エンベロープの2) 円盤ガスの獲得が暴走的に起きる

臨界コア質量コア
01020

時間 [Myr]
木星形成過程の解明にはコア質量が鍵となる

超高圧物性の不明点
Fig. from Guillot et al. (2004)

密度 [g/cc]

Laser compression

Envelope
H2 molecular
H+ metallic

Magne&c compression~1-2Mbar~40MbarCore
圧力 [Mbar]

分子水素→金属水素への転移の仕方および場所が不明

超高圧物性の不明点
PHYSICAL REVIEW B 84, 235109 (2011)

REDMER

028000gH-H (r)present work
Morales 2009

er
upit

1.5
10.5
06000

gHe-He (r)nSatur

He不混和領域

4000

3
2
101

2000

CPlting lin

liquid-liquidHe me

FIG. 6. (Color) Snapshot of a simulation for x = 1/3, ϱ =4 g/cm3 , T = 6000 K, and P ≈ 20 Mbar visualized with the VMD
program (Ref. 72). Shown are the ions (small spheres) and isosurfacesof the specific particle density for ni = 0.5/Å3 . Blue: helium; red:hydrogen.

He

H melting line

001V. DIRECT SIMULATION OF DEMIXING

23Pressure [Mbar]

gH-He(r)Temperature [K]J

4To study the effect of demixing directly, i.e., without using

5 the ideal entropy of mixing or thermodynamic integration,

we have performed simulations with 2048 electrons for x =1/3, i.e., 1024 hydrogen atoms and 512 helium atoms, at aconstant density of ϱ = 4 g/cm3 and temperatures between
6000 and 12 000 K. With this high (and demanding) particle
number it was possible to see demixing effects directly inside
the simulation box. A typical snapshot of such a simulation at
6000 K, i.e., inside the demixing region, is shown in Fig. 6. We
can identify helium-rich (blue) and helium-poor (red) regions.
Note that we did not prepare a demixed state but started from ahomogeneously mixed one and then let the system equilibrate.
After a simulation time of ∼1 ps (a few thousand time steps)
the demixing could be seen clearly and was stable until the endof the simulation (a further 3-ps simulation time). At higher
temperatures the demixing effect decreases.
For a more quantitative evaluation we have calculated
the radial distribution functions from these simulations—seeFIG. 5. (Color online) Demixing region (yellow/light gray area)
ヘリウム不混和層は本当に存在するのか？
for a helium fraction of x = 0.086 in comparison with the isentropes(black) of Jupiterヘリウム分離はどのように進行するのか？
(Ref. 2) (solid line) and Saturn (dashed line). The
filled circles are the calculated data from Fig. 4 and Ref. 22, and theopen circle at 2 Mbar is extracted from thedata in Fig. 1.
→conductivity
惑星放射量や年齢の問題と関係

0.5

00

FIG. 7. (ColorHe, and H-He at ϱ12 000 K.

With increasing
droplet decrease
vanished, in agre
as derived from thfinite-size effects
at the moment noentropy of mixing

10.8

ction xum
lso
Mottolar

Lorenzen, Holst, & Redmer (2011, PRB)HeMETALLIZATION IN HYDROGEN-HELIUM MIXTURES

0.6

内部をもっと直接見たい日震学/星震学を木星に応用
折り返し点の位置 [RJ=1]「木震学」

Jackiewicz+ 121.0

Mol. H2

0.8
0.6

Met. H+

0.4
0.20.0Core110100103

方位量子数 `

折返点の位置・音速と方位量子数の関係

c2s (rt )4⇡ 2 ⌫ 2=2rt`(` + 1)

on here
the frequenciesof theanpulsationeffects
have beenmodes
correspondto roughlyn & 22.
The ‘ ¼
0 modes are
the r
goal
is to provide
overallmodes,
studywhoseon theusefulstrongly
enoughto reachdetectablelevels.
Convectivemodestudied previously (e.g., Vorontsov, 1981; Mosser, 1990; Lee,
dial solutions, whose eigenfunctions have no nodes on the surfac
pulsations on structure determination and these small
tation mechanisms are complex and a full understanding of a1993). While rotation imparts non-negligible shifts in the freIt is unknown whether all modes that we expect to exist in Jup
will quency
not affectour main conclusions.
processes responsible, including damping, is still lacking.
spectrum for non-radial pulsations (on the order of

木震学：理論モデル

ter based on interior models will in fact be excited, or excite
27 lHz), our goal here is to provide an overall study on the useful- We
finallyenoughnote thatthe solution
the differential
strongly
to reachdetectablefinderlevels. ofConvectivemode-exceness of the pulsations on structure determination and these smalltions tationis sensitive
to theareinput
frequency
guess,
and a solution
mechanisms
complexand a fullunderstandingof all th
deviations will not affect our main conclusions.
processes responsible, including damping, is still lacking.
We finally note that the solution finder of the differential equtions is sensitive to the input frequency guess, and a solution is nb)(a)

方位量子数と振動数の関係

周波数 [mHz]

音速 [km/s] 密度 [g/cc]

a)

内部構造の計算結果(b)

中心からの距離 [木星半径=1]

方位量子数

`

2. Computed frequencies0 m0n‘ for each of the three models in ‘ ' m space fFig. 2. Fig.
Computed
frequencies mn‘ for each of the three models in ‘ ' m sp
‘ 6 25 and m 6 3:5 mHz. Several radial orders (n) are labeled for reference. TFig. 1. (a) Density and (b) sound-speed profiles for the three models as a function of‘ 6 25 and m 6 3:5 mHz. Several radial orders (n) are labeled for referenc
ty and (b) sound-speed profiles for the three models as a function ofscaled Jupiter radius, RJ . Noted by arrows are small jumps in density for the LMR
dashed line along the lowest ridge denotes the dispersion relation for the surfac
adius,
RJ . Noted
dashedgravity
line alongthe lowest
denotes
dispersion
the sfbyRJarrows
jumps
densityfor theLMR are also
(fundamental
n ¼ ridge0) mode.
Black thesquares
highlightrelation
the fourfor
modes
model
at ! 0:63
and forare
the small
SCV model
at in! 0:8
RJ . Similarfeaturesgravitywhich(fundamental
n ¼ 0) inmode.
3 RJpresent
and forthesound
SCV speed.
model at ! 0:8 RJ . Similar features are alsokernels are plottedFig. 7. Black squares highlight the four modin theound speed.

which kernels are plotted in Fig. 7.

Jackiewicz+ 12

SYMPA Project
Seismographic Imaging Interferometer for Monitoring Planetary Atmospheres
Gaulme+ 2011`=1800-3000μHzに強度過剰
振幅30cm/s±10cm/sのピークが約20個
ピーク振動数間隔Δν0= 154.5 µHz ± 1.5 µHz→内部構造モデルと整合的

Jovian Oscillations through radial Velocimetry ImAgingobservations at several Longitudes

JOVIAL ネットワーク
Goal: Simultaneous observations from 3 sites
Target: Duty-cycle > 50 % over two weeks
Observatoire de Calern (France)
2015• C2PU: 1 m telescope with DSI prototype
New Mexico (USA)2017• Dunn Solar telescope (Sacramento Peak)Okayama Observatory (Japan)
1.88 m telescope2018 •• Backup: Ishigaki observatory (1m telescope)

The JOVIAL TeamInvolvement(Man-Month)

Organisation

Last nameFirst nameCurrent position

Contribution to the projectLaboratoire Lagrange

SchmiderFrançois-Xavier

Directeur de Recherche

24Principal Investigator

Laboratoire Lagrange

Guillot

TristanDirecteur de Recherche

12

Science Team Leader, Internal structure and evolution model

Laboratoire Lagrange

Goncalves

Ivan

Doctorant18

Data processing

Laboratoire Lagrange

Mekarnia

DjamelChargé de Recherche

6

Observation and data processing

Laboratoire Lagrange

BressonYves

Ingénieur d’Etudes

10

Optical studies, tests

Laboratoire Lagrange

Preis

OlivierIngénieur d’Etudes

12

Project Manager

Laboratoire Lagrange

DejongheJulien

Ingénieur d’Etudes

12

Mechanical studies and integration

Institut d'Astrophysique Spatiale

AppourchauxThierry

Directeur de Recherche

24Partner n°2 Leader
Data analysis

Institut d’Astrophysique Spatiale

BaudinFrédéric

Astronome

10

Data analysis

Institut d’Astrophysique Spatiale

BoumierPatrick

Chargé de Recherche

6Instrumental expertise

Institut d’Astrophysique Spatiale

Le Clec’hJean-Christophe

Ingénieur d’Etudes

4

Thermal control study

Institut d’Astrophysique Spatiale

MorinaudGilles

Ingénieur de Recherche

4

Vacuum tank study

Institut d’Astrophysique Spatiale

Ballans

HervéIngénieur de Recherche

12

Data analysis and archiving

NMSU

GaulmePatrick

Astronomer

9

Commissioning and operation

NMSU

Jackiewicz

Jason

Professor

9

Seismic model

NMSU

Voelz

David

Professor

6

Optical interface

NMSU

UnderwoodTom

PHD student

12

Instrument control software

Tokyo Inst. Of Technology

SatoBu'nei

Associate Professor

6Coordination of the Okayama observations

Tokyo Inst. Of Technology/ELSI

Ida

Shigeru

Full Professor

4Science Interpretation: Solar System formation models

University of TokyoIkoma

Masahiro

Associate Professor

6Science Interpretation: Interior models

観測期間

観測期間

観測装置
Doppler Spectro-Imager (DSI)
木星表面で反射された太陽スペクトルのドップラーシフトを測定

DSI



Mach-Zehnder 干渉計
位相が90度ずつずれた4つの干渉像から時々刻々の位相変化を測定→ 木星表面各点の速度変化
ノイズレベル < 4cm/s in 2 weeks (photon noise)• On sky で ~3 cm/s (in 2.5夜) を達成• 速度精度は ~ 20m/s/“ in 1h (2014年1月時点)

位相が90度ずつずれた

木星の干渉像

設置予定場所
クーデ焦点 (クーデ室内)
HIDESと干渉しないようにする
今年7月にフランスチームが現地視察．泉浦さん・神戸さんを交えて議論

まとめ
木星内部の組成分布には不明な点が多く，それが木星の起源・進化の理解を妨げている
重力場観測に基づいた現行の内部構造推定法では, 深部の情報は取れない
星震学の手法を木星に適用すること(木震学)で, 深部の組成情報を得ることができる
188cmを用いたネットワーク観測(JOVIAL)を提案したい