Application of recent results on the orbital migration of low mass planets: convergence zones

TL;DR

This paper introduces a semi-analytical model for low mass planet migration in non-isothermal disks, revealing convergence zones that can accelerate planetary growth and enable formation of diverse planetary types.

Contribution

It presents a new model incorporating recent non-isothermal migration results, eliminating the need for ad hoc reduction factors in type I migration.

Findings

Identification of zero-torque convergence zones in disks.

Planets migrate towards these zones, aiding growth.

Model supports formation of both close-in low mass and distant giant planets.

Abstract

Previous models of the combined growth and migration of protoplanets needed large ad hoc reduction factors for the type I migration rate as found in the isothermal approximation. In order to eliminate these factors, a simple semi-analytical model is presented that incorporates recent results on the migration of low mass planets in non-isothermal disks. It allows for outward migration. The model is used to conduct planetary populations synthesis calculations. Two points with zero torque are found in the disks. Planets migrate both in- and outward towards these convergence zones. They could be important for accelerating planetary growth by concentrating matter in one point. We also find that the updated type I migration models allow the formation of both close-in low mass planets, but also of giant planets at large semimajor axes. The problem of too rapid migration is significantly mitigated.