Instabilities in the Early Solar System due to a Self-gravitating Disk

Area of Science:

• Planetary Science
• Computational Astrophysics
• Solar System Dynamics

Background:

• Orbital instabilities in the early solar system are often linked to giant planet interactions with exterior planetesimal disks.
• Previous models suggested these instabilities could be delayed by hundreds of millions of years.
• Prior studies often neglected gravitational interactions among planetesimals themselves.

Purpose of the Study:

• To investigate the impact of planetesimal-planetesimal gravitational interactions on giant planet orbital instability.
• To determine if including these interactions alters the timing and characteristics of early solar system instabilities.
• To assess if this mechanism can reproduce observed Jovian eccentricities.

Main Methods:

• Performed N-body numerical simulations using the GENGA code, leveraging GPU acceleration.
• Included all gravitational interactions between simulated bodies, including planetesimals.
• Simulated a massive exterior disk of planetesimals interacting with giant planets.

Main Results:

• Self-stirring of the planetesimal disk significantly impacts giant planet instability dynamics.
• Planetesimal interactions dynamically heat the disk, typically limiting instability delays to tens of millions of years.
• Longer delays were observed only in systems with large gaps (>=3.5 AU) between planets and the disk.
• Final planetary configurations generally matched solar system parameters, with typical Jovian eccentricities comparable to modern values.

Conclusions:

• Gravitational interactions among planetesimals are crucial for early solar system dynamics, not just their interaction with planets.
• The 'self-stirring' effect prevents long delays in giant planet instability, aligning better with some solar system formation models.
• This mechanism offers a potential explanation for matching observed Jovian eccentricities, a challenge for previous models.