Origin of the Different Architectures
of the Jovian and Saturnian Satellite Systems


Takanori Sasaki, Shigeru Ida (Tokyo ...
Jovian System v.s. Saturnian System

                 rocky       rocky         icy      icy, undiff.



                 ...
Questions; Motivation of this study

Satellites’ size, number, and location
 Jovian: 4 similar mass satellites in MMR
 Sat...
Overview of this study

  Circum-Planetary Disk                  Satellite Formation
Canup & Ward, 2002, 2006            I...
Overview of this study

  Circum-Planetary Disk                   Satellite Formation
Canup & Ward, 2002, 2006            ...
Overview of this study

  Circum-Planetary Disk                   Satellite Formation
Canup & Ward, 2002, 2006            ...
Canup & Ward (2002, 2006)

Actively-Supplied Accretion Disk
 Uniform mass infall Fin from the circum-stellar disk
 Infall ...
Canup & Ward (2002, 2006) +α

Inflow flux Fin = Fin (t = 0)exp("t # in )     [g/s]

                            12          ...
Overview of this study

  Circum-Planetary Disk                   Satellite Formation
Canup & Ward, 2002, 2006            ...
Ida & Lin (2004, 2008, in prep.)

    Timescales of satellite’s accretion & type I migration

                M           ...
Overview of this study

  Circum-Planetary Disk                   Satellite Formation
Canup  Ward, 2002, 2006             ...
The Ideas

Jupiter

          inner cavity         opened up gap in c.-s. disk
                                 → infall t...
Inner Cavity (Analogy with T-Tauri stars)




            974                                HERBST  MUNDT
         number...
Inner Cavity (Analogy with T-Tauri stars)
  weak magnetic field                     strong magnetic field → coupling with di...
Inner Cavity (Analogy with T-Tauri stars)
   weak magnetic field                     strong magnetic field → coupling with d...
Estimates of Cavity Opening

                                                   Cavity
Stevenson (1974)
  proto-Jovian mag...
Jovian System




      inner cavity                           outer proto-satellite
    @corotation radius               ...
Jovian System




         Type I migration is
      halted near the inner edge
                       The outer most sate...
Jovian System




                MMR



       Proto-satellites grow  migrate repeatedly
  They are trapped in MMR with t...
Jovian System




      Total mass of the trapped satellites  Disk mass
         → the halting mechanism is not effective
...
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 t...
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 dec...
Results: Distribution of the number of large satellites

                                       Jovian                    ...
Results: Distribution of the number of large satellites

                                       Jovian                    ...
Results: Properties of produced satellite systems

                             Jovian                        Saturnian
  ...
Results: Properties of produced satellite systems

                             Jovian                            Saturnia...
Summary

• Jovian Satellite System v.s. Saturnian Satellite System
   Difference of size, number, location, and compositio...
Cps Hokudai
Cps Hokudai
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Cps Hokudai

  1. 1. Origin of the Different Architectures of the Jovian and Saturnian Satellite Systems Takanori Sasaki, Shigeru Ida (Tokyo Tech) Glen R. Stewart (U. Colorado)
  2. 2. 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
  3. 3. 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?
  4. 4. 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
  5. 5. 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?
  6. 6. 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
  7. 7. 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
  8. 8. 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 &
  9. 9. 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
  10. 10. 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
  11. 11. 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?
  12. 12. 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)
  13. 13. Inner Cavity (Analogy with T-Tauri stars) 974 HERBST MUNDT number of stars Herbst Mundt (2005) spin period [day]
  14. 14. 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]
  15. 15. 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]
  16. 16. 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
  17. 17. 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.
  18. 18. Jovian System Type I migration is halted near the inner edge The outer most satellite migrates and sweeps up the inner small satellites.
  19. 19. Jovian System MMR Proto-satellites grow migrate repeatedly They are trapped in MMR with the innermost satellite
  20. 20. Jovian System Total mass of the trapped satellites Disk mass → the halting mechanism is not effective → Innermost satellite is released to the host planet
  21. 21. Jovian System after the gap opening → c.-p. disk deplete quickly
  22. 22. Saturnian System No inner cavity outer proto-satellite grow faster migrate earlier
  23. 23. Saturnian System fall to Saturn Large proto-satellites migrate from the outer regions and fall to the host planet with inner smaller satellites
  24. 24. Saturnian System c.-p. disk depleted slowly with the decay of c.-s. disk
  25. 25. 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
  26. 26. 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
  27. 27. 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)
  28. 28. 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
  29. 29. 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
  30. 30. 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

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