Giant planet formation in radially structured protoplanetary discs

TL;DR

This study demonstrates that radially structured protoplanetary discs can facilitate the formation of cold gas giants and reproduce the hot-Jupiter/cold-Jupiter distribution, addressing previous migration-related formation failures.

Contribution

The paper introduces a model incorporating radial disc structures that enables the formation of cold Jupiters and explains the observed period distribution of giant exoplanets.

Findings

Radially structured discs lead to successful cold Jupiter formation.

The model reproduces the hot-Jupiter/cold-Jupiter period distribution.

Simulations show a period valley between 10-100 days.

Abstract

Our recent N-body simulations of planetary system formation, incorporating models for the main physical processes thought to be important during the building of planets (i.e. gas disc evolution, migration, planetesimal/boulder accretion, gas accretion onto cores, etc.), have been successful in reproducing some of the broad features of the observed exoplanet population (e.g. compact systems of low mass planets, hot Jupiters), but fail completely to form any surviving cold Jupiters. The primary reason for this failure is rapid inward migration of growing protoplanets during the gas accretion phase, resulting in the delivery of these bodies onto orbits close to the star. Here, we present the results of simulations that examine the formation of gas giant planets in protoplanetary discs that are radially structured due to spatial and temporal variations in the effective viscous stresses, and show that such a model results in the formation of a population of cold gas giants. Furthermore, when combined with models for disc photoevaporation and a central magnetospheric cavity, the simulations reproduce the well-known hot-Jupiter/cold-Jupiter dichotomy in the observed period distribution of giant exoplanets, with a period valley between 10-100 days.