misaligned planets/stars, disks and...

Misaligned Planets/Stars, Disks and Rings

Dong Lai

Cornell University

Nice Observatoire, 12/7/2016

Misaligned Planets/Stars, Disks and Rings

(1)  Binary-Disk-StarInterac4on!Misalignedprotoplanetarydisk

(2)  Secularperturba4onfrombinaryonplanet!MisalignedHotJupiters

(3) MissingKeplerMul4’s

(4)  Extended,misalignedring/diskaroundplanets/browndwarfs

(5)  PlanetIXandsolarobliquity

Othertopics:

•  CircumbinaryDisks(hydro)andcircumbinaryplanets(dynamics)

•  MMRcaptureandstability

MisalignedPlanets

ESO

Alsonote:Misalignedmul4-planetsystems:Kepler-56(2planets10.5&21days,40-55deg;Huber+2013);othercandidates(?):Hirano+2014

How to produce misaligned planets (HJs)?

--“Primordial”misalignmentbetweenspinanddisk

--“Lidov-Kozaimigra?on”inducedbyabinarycompanion--Planet-Planetinterac?ons:dynamicalsca\ering,secularchaos,coplanarhigh-emigra4on(Rasio&Ford96;Cha\erjeeetal.08;Juric&Tremaine08;Nagasawaetal.08;Wu&Lithwick11;Beauge&Nesvorny2012;Petrovich15,16;Petrovich&Tremaine16;Hamersetal.16)

Observa?onalHints:YoungHJs(Dona4+16;David+16)Ngo+15;Bryan+16(Externalcompanions)Huang+16(neighborsofWJs/HJs)

Schlaufman&Winn16(companionsinsideiceline)

Ideas for Producing Primordial Misalignments between Stellar Spin and Protoplanetary Disk

-- Star formation in turbulent medium (Bate+2010; Fielding+2014 ) -- Magnetic Star – Disk Interaction (Lai+2011, Foucart & Lai 2011) -- Perturbation of Binary on Disk (Batygin 2012; Batygin & Adams 2014; Spalding+2015; Lai 2014; Zanazzi & DL’17)

Star-Disk-Binary Interactions

LbLdS

disk

Mb

DL2014

Companion makes disk precess

Disk behaves like a rigid body (bending waves, viscous stress, self-gravity) e.g. Foucart & Lai 2015; Caveat ? (J. Zanazzi & Lai, in prep)

⌦

pd

' �5⇥ 10

�6

✓Mb

M?

◆ ⇣ rout

50 AU

⌘3/2

⇣ ab

300 AU

⌘�3

⇥ cos ✓db

✓2⇡

yr

◆

Disk makes the star precess

Due to gravitational torque from disk on rotating (oblate) star

⌦

ps

' �5⇥ 10

�5

✓Md

0.1M?

◆ ✓¯

⌦?

0.1

◆ ✓rin

4R?

◆�2 ⇣ rout

50 AU

⌘�1

⇥ cos ✓sd

✓2⇡

yr

◆

where

Two limiting cases:

|⌦ps|� |⌦pd| : =) ✓sd ' constant(1)

|⌦ps|⌧ |⌦pd| : =) ✓sb ' constant(2)

⌦

pd

' �5⇥ 10

�6

✓Mb

M?

◆ ⇣ rout

50 AU

⌘3/2

⇣ ab

300 AU

⌘�3

⇥ cos ✓db

✓2⇡

yr

◆

⌦

ps

' �5⇥ 10

�5

✓Md

0.1M?

◆ ✓¯

⌦?

0.1

◆ ✓rin

4R?

◆�2 ⇣ rout

50 AU

⌘�1

⇥ cos ✓sd

✓2⇡

yr

◆

Ini4allyMddecreasesover~1Myr

|⌦ps|� |⌦pd|

✓sd = 5�✓db = 5�Initial:

DL2014

In the frame rotating at rate ⌦pdˆLb

Resonance ⌦ps = ⌦pd

⌦eLe

dSdt

= ⌦psLd ⇥ S

dSdt

!

rot

= ⌦ps

Ld

⇥ S� ⌦pd

Lb

⇥ S

=⇣⌦

ps

Ld

� ⌦pd

Lb

⌘⇥ S

GeometricInterpreta?onLai2014

✓sd = 5�

Initial: ✓db = 30�

Complica?ons:

Accre?onandmagne?cinterac?on

Magnetic Star - Disk Interaction: Basic Picture

Magne4cstar

Nacc ' Mp

GM?rin

Nmag ⇠ µ2/r3inMagnetic (misalignment) torque:

Accretion torque:

Accre?on&Magne?cTorques(Order-of-Mag):

Nacc ' Mp

GM?rin

Nmag ⇠ µ2/r3inMagnetic (misalignment) torque:

rin ⇠✓

µ4

GM?M2

◆1/7

For ! Nacc ⇠ Nmag

Accretion torque:

Accre?on&Magne?cTorques(Order-of-Mag):

Note:Massive(>1.3Sun)TTauristarshaveweakerdipolefieldsthanlessmassivestars.Consequenceonspin-orbitmisalignment?

Star-Disk-Binary Interactions

Gravitational interactions… Now include Accretion and Magnetic Torques

DL2014

No accretion/magnetic

Accretion/magnetic damps SL-angle

Accretion/magnetic increases SL-angle

Summary(#1)Star-disk-binaryinterac?ons

•  Withabinarycompanion,spin-diskmisalignmentis“easily”generated•  Thekeyis“resonancecrossing”•  Accre4on/magne4ctorquesaffectit,butnotdiminishtheeffect!“primordial”misalignmentofstellarspinanddisk

Toorobust??Realis4cdiskevolu4on,diskwarping,planet-diskcoupling(J.Zanazzi’sThesis)

Formation of Hot Jupiters: Lidov-Kozai Migration Driven by a Companion

Holmanetal.97;Wu&Murray03;Fabrycky&Tremaine07;Naozetal.12;Petrovich15,….

Lidov-Kozai Oscillations

planetorbitalaxis

binaryaxis

•  Eccentricityandinclina4onoscilla4onsinducedifi>40degrees.

•  Ifilarge(85-90degrees),getextremelylargeeccentrici4es(e>0.99)

Lidov-Kozai Oscillations: Octupole Effecte.g.Fordetal2000;Naozetal11;Katzetal11;Lithwick&Naoz11;Lietal14;Antognini15

Octupole!--Verylargeeevenformodesti--Lpcanflipwrtouterbinary

IncludingShort-RangeForces!--emaxisreduced/limited--flipisdelayed/suppressed

B.Liu,D.Munoz&DL2015

Lidov-Kozai Oscillations: Octupole Effect + Short-Range Forces

BinLiu,D.Munoz,DL2015

elimWindowofoctupole

Lidov-Kozai Oscillations: Octupole Effect + Short-Range Forces

WindowofOctupole Munoz,DL&Liu16

✏oct

=✓

a

ab

◆eb

1� e2

b

Hot Jupiter formation

"  Planetformsat~afewAU"  Companionstarperiodicallypumpsplanetintohigh-eorbit(Lidov-Kozai)"  Tidaldissipa4oninplanetduringhigh-ephasescausesorbitaldecay!Combinedeffectscanresultinplanetsin~fewdaysorbit

Holmanetal.97;Wu&Murray03;Fabrycky&Tremaine07;Naozetal.12,Katzetal.12;Petrovich15

Q: What is happening to the stellar spin axis ?

Chaotic Dynamics of Stellar Spin Driven by Planets Undergoing Lidov-Kozai Oscillations

With

Natalia Storch (Ph.D.15# Caltech) Kassandra Anderson

Storch, Anderson & DL 2014, Science Storch & DL 2015 MNRAS (Theory I) Anderson, Storch, DL 2016 (Pop Study) Storch, DL & Anderson2016 (Theory II)

Precession of Stellar Spin

•  Starisspinning(3-30days)#oblate#willprecess

Ωs

Mp

Spin Dynamics

•  Stellar spin axis S wants to precess around planet orbital axis L. LB

S

L

θsl θlb

θsb

Ωps

OuterbinaryaxisPlanetorbitalaxisStellarspinaxis

Spin Dynamics

•  Stellar spin axis S wants to precess around planet orbital axis L.

•  But L itself is moving: –  Nodal precession (L precesses

around binary axis Lb) –  Nutation (cyclic changes in

inclination of L relative to Lb)

LB

S

L

θsl θlb

θsb

Ωpl

Ωps


Spin Dynamics

•  Q: Can S keep up with L? •  Answer depends on

LB

S

L

θsl θlb

θsb

Ωpl

Ωps


⌦ps vs ⌦pl

If|Ωps|>>|Ωpl|:YES(“adiaba4c”)


θsl=constant,i.e.ini4alspin-orbitmisalignmentismaintainedforall4me

N.Storch

If|Ωps|<<|Ωpl|:NO(“non-adiaba4c”)


N.Storch

Toanswer,needtosolveorbitalevolu4onequa4onstogetherwithspinprecessionequa4on….

If|Ωps|~|Ωpl|:“trans-adiaba4c”


OuterbinaryaxisPlanetorbitalaxisStellarspinaxisQ:Isitreallychao4c?

N.Storch


Storch,Anderson&DL14

Lyapunov4me~6Myrs

LB

SL

θsl θlb

θsb

Ωpl

Ωps

Complication & Richness Ωps&Ωplarestrongfunc4onsofeccentricity(and4me)

✏ =⌦pl0

⌦ps0

Key parameter:

/ a9/2

Mp⌦s

Thera4ooforbitalprecessionfrequencytospinprecessionfrequencyatzeroeccentricity

Bifurcation Diagram

Valuesrecordedateccentricitymaxima,for1500LK-cycles

Periodicislandsintheoceanofchaos

Quasi-chao4cregionsinthe“calm”sea

Storch,Anderson&DL14;Storch&DL15

Whatabout?daldissipa?on?

Lidov-Kozai + Tidal Dissipation

af

✓fsl

A tiny spread in initial conditions can lead to a large spread in the final spin-orbit misalignment

Memory of Chaos

Initial orbital inclination θlb=85± 0.05°, with spindown

Storch,Anderson&DL14

Distribu?onsofthefinalspin-orbitangle

Parameters:ab=200AUM*=Mb=1MsunStellarspin-downcalibratedsuchthatspinperiod=27daysat5Gyr(Skumanichlaw)Uniformdistribu4onofini4alsemi-majoraxes(a=1.5–3.5AU)

Anderson,Storch&DL16

Solar-typestar FStar(1.4Msun)


Forma?onofHotJupitersinStellarBinariesAnderson,Storch&DL2016

GStars

Forma?oninofHotJupitersinStellarBinariesAnderson,Storch&DL2016

FStars

TheoryofSpinChaos/Evolu?on

InHamiltoniansystem,Chaosarisesfromoverlappingresonances(Chirikovcriterion;1979)

Ωps&Ωplarestrongfunc4onsofeandt(withperiodPe)Whatresonances??

LB

SL

θslθlb

θsb

Ωpl

Ωps

Storch&DL15Storch,DL&Anderson16

Spinprecession Orbit’snodalprecession Orbit’snuta4on

HamiltonianPerturba?onTheory

!

!

Spin-OrbitResonances

Averagespinprecessionfrequency

Integermul4pleofmeanLidov-Kozaifrequency

=

¯

⌦ps = �↵ cos ✓sl = N2⇡

Pe

IndividualResonance

BoundaryofChao?cZoneAnaly4caltheory:Fromoutmostoverlappingresonances

NumericalBifurca?onDiagramStar4ngfromzerospin-orbitangle

Storch&DL2015

Numerical

Theory

TidalDissipa?on:PathstoFinalMisalignmentsStorch,DL,Anderson2016

Experiments with given a0 = 1.5 au, ab = 300 au, etc

I0 = 89�

I0 = 87�

varying stellar rotation period (S-L coupling strength)

TidalDissipa?on:PathstoFinalMisalignmentsCHAOTIC

Adiaba?cResonanceAdvec?on

N.Storch

Bifurca?on!BimodalDistribu?onMisalignment

Pendulumwithgraduallydecreasinglength…

Summary(#2)Chao?cStellarSpinandForma?onofHotJupiters

•  Dynamicsofstellarspinisimportantfortheforma4onofhotJupiters,e.g.affectstheobservedspin-orbitmisalignments(dependenceonplanetmass,stellarrota4on/historyetc)

•  Spindynamicscanbechao4c•  Spindynamics/evolu4oncanbeunderstoodfromresonancetheory•  Migra4onfrac4onscanbecalculatedanaly4cally

Missing Kepler Multi’s?

DL & Bonan Pu arXiv:1606.08855

Multi-Planet System with an External Companion

Kepler:4700planetsin3600systems (mostlysuper-earthorsub-neptunes,<200days)

NumberofTransi?ngplanets

Num

bero

fsystems

ObservedTransitMul?plicityDistribu?onF(Ntran)

F(Ntran)===>theunderlyingmul?plicitydistribu?on(&mutualinclina?ons)DegeneracycanbebrokenbyRVdata(Tremaine&Dong12)Transitdura4onra4o(Fabrycky+14)

Keplercompactsystemsareflat,withmutualinclina?ondispersion<2degrees

Lissauer+11,Tremaine&Dong12,Figueira+12,Fabrycky+14;Fang&Margot12

ExcessofKeplerSingles(?)

Otherevidencethat(some)Keplersinglesare“special”:(1)  “singles”havehigherstellarobliqui4es(Morton&Winn14)(2)  Mul4’shavemoredetectableTTVsthan“singles”(Xie,Wu&Lithwick14)(3)  10-30%ofsingleshavehighere’s(Xie,S.Dongetal2016)(4)  Single“HotEarth”excess(JasonStaffen)

Modelswithsinglemutualinclina4ondispersion(inRayleigh)fallshorttoexplaintheobservednumberofKeplersingles(Lissauer+11;Johansen+12;Ballard&Johnson16)(dependssomewhatontheassumedmul4plicityfunc4on)

SomeKeplersinglesmightbemul?-planetsystemswithhighermutualinclina?ons…

EffectofExternalPerturberOnCompactMul?-PlanetSystem

Perturber:Giantplanet(~AUs)orCompanionStar(~10’sAUs)

Two-planetsystemwithanexternalinclinedperturber

✓p

m1 m2

mp

m1,m2ini4allyco-planar…

companionstaror“coldJupiter”(e.g.producedbyplanet-planetsca\erings)

✓p

m1

mpLp

L1

⌦1p ⇠ mp

M?

✓a1ap

◆3

n1 / mp

a3pa3/21

Precessionof“1”drivenby“p”:

m1 m2

mp

⌦1p

⌦2p

!12

!21

Mutualinclina4oninducedbyperturberdependsonCouplingParameter

/ mp

a3p

MaximumMutualInclina?onInducedbyexternalperturber

✓p = 10�

(✓12

)max

' ✏12

sin 2✓p

mp

m1 m2

⌦1p

⌦2p

!12

NodalPrecessionResonance

ResonanceFeature:exists when m2 & m1

✏12 ⇠ 1

In the m2 � m1 limit:Resonance occurs at ⌦2p = ⌦1p + !12 or ✏12 = 1

ResonanceFeature:✏12 ⇠ 1

Can produce much larger mutual inclination than ✓p

Mul?-planetsystemwithanexternalinclinedperturber

✓p

m1 m2

mp

m3 m4

4planetsystemwithanexternalperturber

averaged coupling parameter / mp/a3p

dispersionofmutualinclination

Recap:

✓p

m1 m2

mp

Anunderstandingandsemi-analy?cexpressionforthemutualinclina4onofmul4-planetsinducedbydistantperturber

For ✏12 & 2 : ✓12 ⇠ 2✓pFor ✏12 . 0.3 : ✓12 ⇠ ✏12 sin 2✓p

e.g., for m2 ⇠ m� at a2 ⇠ 0.3 au

1MJ perturber at 3 au gives ✏12 ⇠ 0.3

✏12 =⌦2p � ⌦1p

!12 + !21⇠

✓mp

m2

◆✓a2ap

◆3

for m2 ⇠ m1, a2 ⇠ 1.5a1

Applica?on:“Evaluate”/constrainexternalperturberofobservedsystems

Examples:(seeDL&Puformore)

Kepler-68:Twosuper-Earthsat0.06,0.09au,1MJplanetat1.4auisweakKepler-56:…WASP-47:...Kepler-48:Threetransi4ngplanets(0.012,0.046,0.015MJ)at0.053,0.085,0.23au,

>2MJcompanion(Kepler-48e)at1.85au(Marcy+14) !Kepler-48emustbealigned<2degree

Kepler-454:onesuper-Earthat0.1auwitha>5MJat524days(Ge\el+16) !anyneighbortotheinnerplanetcouldbestronglymisalignedbythegiant (Thiscouldofmul4-planetsystemthathasbeenturnedintoKeplersingle byanexternalgiantplanet)

ConfrontwithObserva?ons?

Some/significant(?)frac4onofKeplersingles(Ntran=1)are/weremul4-planetsystemsthathavebeenmisaligned(inmutualinclina4ons)ordisruptedbyexternalperturbers(coldgiantplanetsorstellarcompanions)

ColdGiantPlanets:Somehavebeenfound,butgeneralcensusnotclear?

(50%ofHJs/WJshave1-20MJcompanionat5-20au;Bryanetal2016)

StellarCompanions:J.Wangetal(2015):~5%ofKeplermul4shavestellarcompanion1-100au

(4xlowerthanfieldstars)

Morestudiesareneeded.

Extended&InclindedDisks/RingsaroundPlanets/BrownDwarfs

J.J.Zanazzi&DL2016

Lightcurveof1SWASPJ1407(~16Myr,0.9Msun)Aseries“eclipses”las4ng56daysaroundApril2007:

bigeclipse(3.5mag)withsymmetricpairsofsmaller(~mag)eclipses

Mamajeketal.2012vanWerkhovenetal.2014Kenworthyetal.2015

!Largering/disksystemaroundunseensubstellarcompanion(?)

Kenworthy&Mamajek2015

Claimedbestfitmodel:Ringsize~0.6AU,withgaps(moons?),totalmass~1M_earthOrbitalperiod10-30years(eccentric)

Ques?on:Underwhatcondi?onscananextended,inclinedring/diskexistaroundaplanet/BD?

•  Outerradiusofring

•  Howtoproduce/maintaininclina4on?

rout

. 0.3rH rH = a

✓Mp

3M?

◆1/3

planet

M?S

ring

lorb

l(r)

Ring at radius r experiences two torques

From star :

From oblate planet:

Slorb

l(r)

T? ⇠GM?r2

a3

Tp ⇠G(J2MpR2

p)r3

rL ⇠✓

J2Mp

M?R2

pa3

◆1/5

⇠ (3J2R2pr

3H)1/5

T? = Tp at Laplace radius :

�

Slorb

l(r)

�

EquilibriumState:LaplaceSurface

Howtomakethedisksufficiently“rigid”tohaveappreciable

•  Internalstresses(pressure,viscosity):Noteffec4veforthinrings

•  Self-gravity:

�(rout

)?

Tsg ⇠ ⇡Gr⌃

T? ⇠GM?r2

a3 Tp ⇠G(J2MpR2

p)r3Compareto

Howtomakethedisksufficiently“rigid”tohaveappreciable

•  Internalstresses(pressure,viscosity):Noteffec4veforthinrings

•  Self-gravity:

�(rout

)?

Tsg ⇠ ⇡Gr⌃

T? ⇠GM?r2

a3 Tp ⇠G(J2MpR2

p)r3Compareto

Tsg

(rout

) ⇠ GMd

rout

& T?(rout

)

� ⌘ Md

M?

✓a

rout

◆3

=3Md

Mp

✓rH

rout

◆3

& 1

EquilibriumStatewithSelf-Gravity

T? + Tp + Tsg = 0

EquilibriumStatewithSelf-Gravity(modifiedLaplaceSurface)

Whatifdisknotinequilibrium?Candisk“precess”coherently?

Slorb

l(r)

�

Timeevolu?onofdiskr2⌦

@ l(r, t)@t

= T? + Tp + Tsg

Initial l(r, 0) aligned with S (at � = 40�)

Inner disk (Tp & Tsg, T?): stays aligned with S

Outer disk (Tsg & Tp): evolves coherently if Tsg(r) & T?(r)() � & 1

nutation in �, precession (smaller �)/libration (larger �) in �

Timeevolu?onofdisk

Summary(#4)Extended,InclinedDisk/RingAroundPlanets/BDs

•  Intriguing“eclipses”ofJ1407duetoextendeddisk/ring?•  rHandrL•  Ifrout<rL,diskisinclinedwrtorbit(provideSinclinedwrtorbit)•  Ifrout>rL,requiresufficientdiskmassforself-gravitytomaintaindiskcoherenceandoutdiskinclina4on--generalizedLaplacesurface(withself-gravity)--precessing/libra4ng/nuta4ngself-gravita4ngdisk

Md

Mp& 1

3

✓rout

rH

◆3

~10Earthmass,a~700AU,e=0.6(distance300-1000AU,period20,000years) inclinedby10-30degrees

Thanks

TidalDissipa?on:PathstoFinalMisalignments“Regular”

Condi?onforLKMigra?on,Frac?ons...Forgivenini4alaofplanet,emaxmustbesufficientlylargesothata(1–emax)issmallenoughforefficient4daldissipa4on

emax

= emax

(a, ab, M?, Mb, Mp, Rp, · · · ; i0

)

(1) elim(a, ab, M?, Mb, Mp, Rp, · · · ) large enough


Condi?onforLKMigra?on,Frac?ons...Forgivenini4alaofplanet,emaxmustbesufficientlylargesothata(1–emax)issmallenoughforefficient4daldissipa4on

emax

= emax

(a, ab, M?, Mb, Mp, Rp, · · · ; i0

)

(1)(2)i0largeenough(Octupolewindow)

elim(a, ab, M?, Mb, Mp, Rp, · · · ) large enough

Analy4ccalcua4onsofmigra4on/disrup4onfrac4onsforalltypesofplanets(Munoz,DL&Liu2016)

Modelswithsingleinclina?ondispersion(e.g.inRayleigh)donotfitwell:Under-predictKeplersinglesbyafactorof>2

Lissauer+11,Johansen,Davies+12,Weissbein+12,Ballard&Johnson+16

NumberofTransi?ngplanets

Num

bero

fsystems

Red:best-fittomu4ple-transitplanetsystemswithsingleInclina4ondispersion

“KeplerDichotomy”

Keplersystemsconsistofatleasttwounderlyingpopula?ons:(1) SystemsN>~6planetswithsmallmutualinclina4ons(~2degrees):AccountformostofKeplerMul4’s(Ntran>1)

(2)Systemswithfewerplanetsorwithhighermutualinclina4ons:Accountfora(large)frac4onKeplersingles(Ntran=1)

OriginofKeplerDichotomy

--Primordialin-situassemblyofplanetesimaldiskswithdifferentmass&densityprofile(Mariarty&Ballard15)--Dynamicalinstability4ghtlypackedsystem#unstable#collision/consolida4on(Volk&Gladman15;Pu&Wu15)--ExternalPerturber(Giantplanetorcompanionstar)

GeneralComment:InfluencesofExternalPerturberson(Inner)PlanetarySystems

---Mutualinclina4ons(DL&Pu2016)---Forma4onofHotJupitersandWarmJupiters(high-emigra4on)(manypapers…)e.g.High-emigra4oninducedbystellarcompanioncontrinutes

~10-15%ofHJs(Petrovich15;Anderson,Storch&DL16;Munoz,DL+16)---Evec4onresonance(Touma&Sridhar15;Xu&DL16)

misaligned planets/stars, disks and...

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