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

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)

Time

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;…)

Jupiter

Saturn

Orb

ital

rad

ius

2/3 resonance locking

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

Terrestrial Planets formation from a disk of planetesimals and planetary embryos, ranging from the Sun to Jupiter’s current orbit….

..produce a Mars analog systematically too big!

Raymond et al., 2009

Inner edge @ 0.7 AU

Outer edge @ 1.0 AU

Hansen, 2009

Ida & Lin, 2008 ?

Can the “Grand Tack” of Jupiter explain this?

Grand Tack

We did simulations assuming a Grand Tack evolution scenario, with Jupiter reversing migration at ~1.5 AU

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

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

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

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

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

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

Gliese 876

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

Kley et al. 2004, 2005; Crida et al., 2008

For more discussion see my chapter “Dynamics of Planetary Systems” available on AstroPH

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?

NO

YES

CONCLUSIONS

Does the eccentricity saturate ?

YES

NO

HD 12661& Co.

Solar System

resonant pairs (Gliese 876)

Eccentric single planets