Magnitude and timing of the giant planet instability: A reassessment from the perspective of the asteroid belt

Abstract

It is generally accepted today that our solar system has undergone a phase during which the orbits of the giant planets became very unstable. In recent years, many studies have identified traces of this event and have provided reasonable justification for this occurrence. The magnitude (in terms of orbital variation) and the timing of the instability though (early or late with respect to the dispersal of the gas disk) still remains an open debate. The terrestrial planets seem to set a strict constraint: either the giant planet instability happened early, while the terrestrial planets were still forming, or the orbits of Jupiter and Saturn had to separate from each other impulsively, with a large enough `jump' in semimajor axis (Brasser et al. 2009; Kaib and Chambers 2016) for the terrestrial planets to remain stable. Because a large orbital jump is a low probability event, the early instability hypothesis seems to be favored. However, the asteroid belt would also evolve in a different way, assuming different instability amplitudes. These two constraints need to match each other in order to favor one scenario over the other. Considering an initially dynamically cold disk of asteroids, Morbidelli et al. (2010) concluded that a comparably large jump is needed to reconstruct the current asteroid belt. Here we confirm the same conclusion, but considering an asteroid population already strongly excited in eccentricity, such as that produced in the Grand Tack scenario (Walsh et al. 2011). Because the asteroids existed since the time of removal of the gas disk, unlike the terrestrial planets, this constraint on the width of the giant planet jump is valid regardless of whether the instability happened early or late. Hence, at this stage, assuming an early instability does not appear to provide any advantage in terms of the probabilistic reconstruction of the solar system structure.

References in corpus (3)

• Origin of the Structure of the Kuiper Belt during a Dynamical Instability in the Orbits of Uranus and Neptune
• The Fragility of the Terrestrial Planets During a Giant Planet Instability
• Is the Grand Tack model compatible with the orbital distribution of main belt asteroids?

Cited by in corpus (10)

• Dynamical Evolution of the Early Solar System
• Constraining the giant planets' initial configuration from their evolution: implications for the timing of the planetary instability
• Modeling the Historical Flux of Planetary Impactors
• How primordial is the structure of comet 67P/C-G? Combined collisional and dynamical models suggest a late formation
• The excitation of a primordial cold asteroid belt as an outcome of the planetary instability
• A record of the final phase of giant planet migration fossilized in the asteroid belt's orbital structure
• Instabilities in the Early Solar System due to a Self-gravitating Disk
• Checking the Compatibility of the Cold Kuiper Belt with a Planetary Instability Migration Model
• Formation of Terrestrial Planets
• Eccentricity distribution in the main asteroid belt