Runaway Growth of Planetesimals Revisited: Presenting Criteria Required for Realistic Modeling of Planetesimal Growth

Abstract

We have initiated a large project on identifying the requirements for developing a realistic and ground-up approach to simulating the formation of terrestrial planets in our solar system. As the first phase of this project, we present here the criteria that any model of planetesimal growth needs to fulfill in order to be self-consistent and produce reliable results. We demonstrate how these criteria emerge by revisiting runaway growth and carrying out a thorough analysis of its results. As our goal is to identify the pathway to a realistic model, we focus analysis on simulations where at the beginning, planetesimals are not artificially enlarged. We show how using uninflated planetesimals, as the first requirement for a realistic model, will result in a set of criteria naturally emerging from the evolution of the system. For instance, the growth times in simulations with uninflated planetesimals become comparable to the time of giant planet formation implying that any realistic simulation of planetesimal growth, in addition to using real-size planetesimals, needs to include the perturbation of the growing giant planets as well. Our analysis also points to a strong connection between the initial distribution of planetesimals and the final outcome. For instance, due to their natural expansion, initially isolated distributions, or a collection of initially isolated distributions, such as rings of planetesimals, do not produce reliable results. In a self-consistent and realistic model, where the initial conditions are supported by basic principles and do not include simplifying, ad hoc assumptions, the entire disk of planetesimals has to be simulated at once. We present the results of our analyses and discuss their implied criteria.

49 pages, 8 figures, 3 tables. Accepted for publication in the International Journal of Astrobiology. We strongly recommend reading the Rationale and Introduction where we present an in-depth review of the development of the field

References in corpus (16)

• Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
• The timeline of the Lunar bombardment - revisited
• Contemporary formation of early solar system planetesimals at two distinct radial locations
• Planetesimal rings as the cause of the Solar System's planetary architecture
• A Hybrid N-body--Coagulation Code for Planet Formation
• A Collisional Origin to Earth's Non-chondritic Composition?
• Formation and accretion history of terrestrial planets from runaway growth through to late time: implications for orbital eccentricity
• Dynamics and Accretion of Planetesimals
• Terrestrial planet formation by torque-driven convergent migration of planetary embryos
• Numerically Predicted Indirect Signatures of Terrestrial Planet Formation
• Debris disc formation induced by planetary growth
• Realistic collisional water transport during terrestrial planet formation: Self-consistent modeling by an N-body--SPH hybrid code
• Forming Iron-rich Planets with Giant Impacts
• Building Terrestrial Planets: Why results of perfect-merging simulations are not quantitatively reliable approximations to accurate modeling of terrestrial planet formation
• Protoplanet Collisions: Statistical Properties of Ejecta
• Orbital evolution of planetesimals in gaseous disks