Cps Hokudai

Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems Takanori Sasaki, Shigeru Ida (Tokyo Tech) Glen R. Stewart (U. Colorado)

Jovian System v.s. Saturnian System rocky rocky icy icy, undiff. Io Europa Ganymede Callisto mutual mean motion resonances (MMR) icy only one big body (~95% of total satellite mass) Titan

Questions; Motivation of this study Satellites’ size, number, and location Jovian: 4 similar mass satellites in MMR Saturnian: only 1 large satellite far from Saturn What is the origin of the different architecture? Among Galilean satellites Io & Europa: rocky satellite Ganymede & Callisto: icy satellite Callisto: undifferentiated What is the origin of the satellites’ diversity?

Overview of this study Circum-Planetary Disk Satellite Formation Canup & Ward, 2002, 2006 Ida & Lin, 2004, 2008, in prep. Satellites formed in c.-p. disk Analytical solution for Actively-supplied accretion disk accretion timescale Supplied from circum-stellar disk type I migration timescale → Analytical solution for T, Σ trapping condition in MMR

Overview of this study Circum-Planetary Disk Satellite Formation Canup & Ward, 2002, 2006 Ida & Lin, 2004, 2008, in prep. Satellites formed in c.-p. disk Analytical solution for Actively-supplied accretion disk accretion timescale Supplied from circum-stellar disk type I migration timescale → Analytical solution for T, Σ trapping condition in MMR Adding New Ideas Disk boundary conditions Difference of Jovian/Saturnian systems is naturally reproduced?

Overview of this study Circum-Planetary Disk Satellite Formation Canup & Ward, 2002, 2006 Ida & Lin, 2004, 2008, in prep. Satellites formed in c.-p. disk Analytical solution for Actively-supplied accretion disk accretion timescale Supplied from circum-stellar disk type I migration timescale → Analytical solution for T, Σ trapping in MMR Adding New Ideas Disk boundary conditions Difference of Jovian/Saturnian system is naturally reproduced

Canup & Ward (2002, 2006) Actively-Supplied Accretion Disk Uniform mass infall Fin from the circum-stellar disk Infall regions: rin < r < rc (rc ~ 30Rp) Diffuse out at outer edge: rd ~ 150Rp Infall rate decays exponentially with time Temperature: balance of viscous heating and blackbody radiation Viscosity: α model

Canup & Ward (2002, 2006) +α Inﬂow ﬂux Fin = Fin (t = 0)exp("t # in ) [g/s] 12 +1 4 +3 4 # Mp & # )G & # r & Temperature Td " 160% ( % 6 ( % ( [K] $ M J ' $ 5 *10 yrs ' $ 20RJ ' ! Gas density [g/cm2] ! Dust density [g/cm2] (2 3 (1 (1 34 Increasing rate df d " Mp % " f % " )G % " r % = 0.029$ ' $ ' $ 6 ' $ ' [/years] of dust density dt # MJ & #100 & # 5 *10 yrs & # 20RJ &

Overview of this study Circum-Planetary Disk Satellite Formation Canup & Ward, 2002, 2006 Ida & Lin, 2004, 2008, in prep. Satellites formed in c.-p. disk Analytical solution for Actively-supplied accretion disk accretion timescale Supplied from circum-stellar disk type I migration timescale → Analytical solution for T, Σ trapping in MMR Adding New Ideas Disk boundary conditions Difference of Jovian/Saturnian system is naturally reproduced

Ida & Lin (2004, 2008, in prep.) Timescales of satellite’s accretion & type I migration M ' & *1 3 ' M *1 3 ' M *$5 / 6 ' - * 2 ' r * 5 4 " acc = # 10 6 f d$1%$1 ) , ) $4 ice ) , ) p, ) , ) , )10 M , M , [years] ˙ M ( 10 + ( 20RJ + ( &p + ( p+ ( J + r 1 % M ($1% M ($1% r (1 2 % " ($1 4 " mig = # 10 5 ' $4 * ' p* ' ' 10 M * M * ' G 6* [years] ! ˙ r fg & p) & J ) & 20RJ ) & 5 +10 ) Resonant trapping width of migrating proto-satellites ! 1/6 −1/4 m i + mj vmig btrap = 0.16 rH M⊕ vK These approximate analytical solutions are based on the results of N-body simulations

Overview of this study Circum-Planetary Disk Satellite Formation Canup & Ward, 2002, 2006 Ida & Lin, 2004, 2008, in prep. Satellites formed in c.-p. disk Analytical solution for Actively-supplied accretion disk accretion timescale Supplied from circum-stellar disk type I migration timescale → Analytical solution for T, Σ trapping condition in MMR Adding New Ideas Disk boundary conditions Difference of Jovian/Saturnian systems is naturally reproduced?

The Ideas Jupiter inner cavity opened up gap in c.-s. disk → infall to c.-p. disk stop abruptly Saturn no cavity did not open up gap in c.-s. disk → c.-p. disk decay with c.-s. disk Difference of “inner cavity” is from Königl (1991) and Stevenson (1974) Difference of gap conditions is from Ida & Lin (2004)

Inner Cavity (Analogy with T-Tauri stars) 974 HERBST & MUNDT number of stars Herbst & Mundt (2005) spin period [day]

Inner Cavity (Analogy with T-Tauri stars) weak magnetic ﬁeld strong magnetic ﬁeld → coupling with disk No Cavity Cavity 974 HERBST & MUNDT If the magnetic torque is stronger than the viscous torque, the disk would be truncated at the number of stars corotation radius Herbst & Mundt (2005) spin period [day]

Inner Cavity (Analogy with T-Tauri stars) weak magnetic ﬁeld strong magnetic ﬁeld → coupling with disk No Cavity Cavity 974 HERBST & MUNDT Saturnian Jovian number of stars Herbst & Mundt (2005) spin period [day]

Estimates of Cavity Opening Cavity Stevenson (1974) proto-Jovian magnetic field 1000 Gauss < Königl (1991) magnetic field for the magnetic coupling accretion rate 10-6MJ/yr → a few hundred Gauss < Present Saturnian magnetic field < 1 Gauss No Cavity ≒ late stage of Saturnian satellite formation

Jovian System inner cavity outer proto-satellite @corotation radius grow faster & migrate earlier Because the infall mass ﬂux per unit area is constant, the total mass ﬂux to satellite feeding zones is larger in outer regions.

Jovian System Type I migration is halted near the inner edge The outer most satellite migrates and sweeps up the inner small satellites.

Jovian System MMR Proto-satellites grow & migrate repeatedly They are trapped in MMR with the innermost satellite

Jovian System Total mass of the trapped satellites > Disk mass → the halting mechanism is not effective → Innermost satellite is released to the host planet

Jovian System after the gap opening → c.-p. disk deplete quickly

Saturnian System No inner cavity outer proto-satellite grow faster & migrate earlier

Saturnian System fall to Saturn Large proto-satellites migrate from the outer regions and fall to the host planet with inner smaller satellites

Saturnian System c.-p. disk depleted slowly with the decay of c.-s. disk

Monte Carlo Simulation (n=100) Parameters: Disk viscosity (α model) α = 10−3 − 10−2 Disk decay timescale τin = 3 × 10 − 5 × 10 6 6 yr Number of “satellite seeds” N = 10 − 20

Results: Distribution of the number of large satellites Jovian Saturnian 40 80 Total count of the case 60 20 40 20 0 0 0 1 2 3 4 5 6 7 0 1 2 3 4 number of produced satellites

Results: Distribution of the number of large satellites Jovian Saturnian 40 80 Total count of the case 60 20 40 20 0 0 0 1 2 3 4 5 6 7 0 1 2 3 4 number of produced satellites inner two bodies: rocky icy satellite & outer two bodies: icy & large enough (~MTitan)

Results: Properties of produced satellite systems Jovian Saturnian 1e-3 Galilean Satellites Titan 1e-4 Ms/Mp 1e-5 rocky component icy component 1e-6 0 10 20 30 0 10 20 30 a/Rp

Results: Properties of produced satellite systems Jovian Saturnian 1e-3 Galilean Satellites Titan 1e-4 Ms/Mp 1e-5 rocky component icy component 1e-6 0 10 20 30 0 10 20 30 a/Rp inner three bodies the largest satellite are trapped in MMR has ~90% of total satellite mass

Summary • Jovian Satellite System v.s. Saturnian Satellite System Difference of size, number, location, and compositions • Satellite Accretion/Migration in Circum-Planetary Disk Canup & Ward (2002, 2006) + Ida & Lin (2004, 2008, in prep.) • The Ideas of Disk Boundary Conditions Difference of inner cavity opening and gap opening conditions • Monte Carlo Simulations Difference of Jovian/Saturnian system are naturally reproduced • Application to Solar/Super-Earths Systems

Cps Hokudai

by noinoi79528 on Nov 12, 2009

Accessibility

Upload Details

Usage Rights

1 Embed 30

Statistics

Cps Hokudai — Presentation Transcript