1. The Grand Tack Scenario: Reconstructing The Migration History Of Jupiter And Saturn In The Disk Of Gas
Alessandro Morbidelli (OCA, Nice)
Kevin Walsh (SWRI, Boulder)
Sean Raymond (CNRS, Bordeaux)
David O’Brien (PSI, Tucson)
Avi Mandell (NASA Goddard)
HELMHOLTZ ALLIANCE: Planetary Evolution and Life

2. Probably responsible for the origin of Hot and Warm Jupiters
Migration of giant planets embedded in a gas-disk seems to be a generic process.
Probably responsible for the origin of Hot and Warm Jupiters
Why then Jupiter is not in the terrestrial planet zone?
Our giant planets, somehow, did not migrate significantly
Our giant planets migrated significantly but ended up onto their distant orbits because of their specific properties (mass ratio & accretion history)

3. Hydro-dynamical simulation of the evolution of Jupiter and Saturn in a gas-disk (Masset and Snellgrove, 2001; Morbidelli and Crida, 2007; Pierens and Nelson, 2008;…)
Saturn
Orbital radius
2/3 resonance locking
Jupiter
Time

4. How far inwards did Jupiter go?
Is there any evidence for such inward-then-outward migration of Jupiter?
How far inwards did Jupiter go?
To answer these questions we need to turn to constraints:
TERRESTRIAL PLANETS
ASTEROID POPULATIONS

5. ..produce a Mars analog systematically too big!
Terrestrial Planets formation from a disk of planetesimals and planetary embryos, ranging from the Sun to Jupiter’s current orbit….
Raymond et al., 2009
..produce a Mars analog systematically too big!

6. Hansen, 2009
Outer 1.0 AU ?
Ida & Lin, 2008
Inner 0.7 AU

7. Can the “Grand Tack” of Jupiter explain this?
We did simulations assuming a Grand Tack evolution scenario, with Jupiter reversing migration at ~1.5 AU
Grand Tack

8. Walsh, Morbidelli, Raymond, O’Brien, Mandell, Nature, 2011

9. Walsh, Morbidelli, Raymond, O’Brien, Mandell, Nature, 2011

10. The Grand Tack scenario explains:
Why Jupiter is not currently in the inner solar system
The structure of the terrestrial planet system (large mass ratio Earth/Mars)
The structure of the asteroid belt (mass deficit, co-existence of two different classes of asteroids)
The initial conditions of the “Nice model” (all giant planets in resonance with each other), which then explains the origin of the current architecture of the outer Solar System
TURNING THE ARGUMENT AROUND:
We believe that there is substantial evidence in the current structure of the Solar System for a wide-range migration of Jupiter and Saturn in the solar nebula of the Grand Tack type

11. PLACING THE SOLAR SYSTEM IN CONTEXT
Our model for the evolution of the Solar System highlights the importance of a few yes/no events that alone can explain most of the diversity that we see
Suppose giant planets form from a system of cores near the snowline and that they grow in mass sequence, from the innermost to the outermost one
First event:
Does the second, lighter planet catch the first one in resonance?
Yes/No
For the Solar System the answer is YES
For HD 12661, HD , HIP14810 the answer is NO

12. Second event:
Does the second planet eventually grow as massive or more massive than the inner one?
Yes/No
For the Solar System (or OGLE L) the answer is NO
For many/most other systems the answer could be YES
If the outer planet eventually exceeds in mass the inner one, inward migration starts again

13. Migration drives the inner, lighter planet to become eccentric
Gliese 876
Kley et al. 2004, 2005; Crida et al., 2008
Migration drives the inner, lighter planet to become eccentric
Third event:
Does the eccentricity saturate ?
Yes/No
For the pairs of stable resonant planets: YES
For eccentric single planets (which presumably got unstable at some time): NO

14. Eccentric single planets resonant pairs (Gliese 876)
CONCLUSIONS
Three events can explain most of the observed diversity:
Does the second, lighter planet catch the first one in resonance? NO
YES
Does the second planet eventually grow as massive or more massive than the inner one?
HD 12661& Co. NO
YES
Does the eccentricity saturate ?
Solar System NO
YES
For more discussion see my chapter “Dynamics of Planetary Systems” available on AstroPH
Eccentric single planets
resonant pairs (Gliese 876)