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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)
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;…)
Orbital radius
Saturn
2/3 resonance
locking
Jupiter
Time
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….
Raymond et al., 2009
..produce a Mars
analog systematically
too big!
Hansen, 2009
Ida & Lin, 2008
Inner edge
@ 0.7 AU
Outer edge
@ 1.0 AU
?
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
Walsh, Morbidelli, Raymond, O’Brien, Mandell, Nature, 2011
Walsh, Morbidelli, Raymond, O’Brien, Mandell, Nature, 2011
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
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
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
CONCLUSIONS
Three events can explain most of the observed diversity:
Does the second, lighter planet catch
the first one in resonance?
NO
HD 12661& Co.
YES
Does the second planet eventually grow as
massive or more massive than the inner one?
NO
YES
Does the eccentricity saturate ?
Solar System
NO
For more discussion see my chapter
“Dynamics of Planetary Systems”
available on AstroPH
Eccentric
single planets
YES
resonant pairs
(Gliese 876)