The Diversity of Planetary Systems Architectures: Contrasting Theory with Observations

TL;DR

This study develops a semi-analytical model to explain the diversity of planetary system architectures based on initial disc properties, matching observations and predicting common system types in the solar neighborhood.

Contribution

It introduces a new semi-analytical model linking initial protoplanetary disc conditions to resulting planetary system architectures, aligning theory with observed diversity.

Findings

Terrestrial-only systems are most common, especially in low-metallicity discs.

Solar system-like architectures are favored in massive, less solid-rich discs.

Hot and warm Jupiter systems originate from massive, metal-rich discs with rapid migration.

Abstract

We develop a semi-analytical model for computing planetary system formation with the aim of explaining the observed diversity of planetary systems architectures and relate this primordial diversity with the initial properties of the disc where they were born. We adopt different initial conditions based on recent results in protoplanetary discs observations, to generate a variety of planetary systems and analyze them statistically. We explore the relevance of the mass and size of the disc, its metallicity, the mass of the central star and the time-scale of gaseous disc dissipation, in defining the architecture of the planetary system. We also test different values of some key parameters of our model, to find out which factors best reproduce the diverse sample of observed planetary systems. According to this, we predict which systems are the most common in the solar neighbourhood. Our results show that planetary systems with only terrestrial planets are the most common, being the only planetary systems formed when considering low metallicity discs and which also represent the best environment for the developing of rocky, potentially habitable planets. We also found that planetary systems like our own are not rare in the solar neighbourhood, being its formation favoured in massive discs where there is not a large accumulation of solids in the inner region of the disc. Regarding the planetary systems that harbor hot and warm Jupiter planets, we found that this systems are born in very massive, metal-rich discs. Also a fast migration rate is required in order to form these systems. According to our results, most of the hot and warm Jupiter systems are composed by only one giant planet, which is also a tendency of the current observational data.