Alessandro Morbidelli (OCA, Nice) Kevin Walsh (SWRI, Boulder) Sean Raymond (CNRS, Bordeaux)

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. 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. 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. 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 edge @ 1.0 AU ? Ida & Lin, 2008 Inner edge @ 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 nebulaof 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 134987, 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 106-09L) 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. 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. Three events can explain most of the observed diversity: CONCLUSIONS 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)