# Planetesimal formation by the streaming instability in a photoevaporating disk

## TL;DR

This study presents a comprehensive global model of protoplanetary disk evolution that incorporates streaming instability and photoevaporation, demonstrating efficient planetesimal formation especially beyond 100 au, but highlighting the need for additional processes for inner disk planetesimal formation.

## Contribution

It introduces a detailed, global simulation model combining streaming instability with photoevaporation, dust evolution, and turbulence, advancing understanding of planetesimal formation across the disk.

## Key findings

- Massive planetesimal belts form beyond 100 au.
- Inner disk forms up to 8 M⊕ of planetesimals within 3 au.
- Photoevaporation influences the timing and location of planetesimal formation.

## Abstract

Recent years have seen growing interest in the streaming instability as a candidate mechanism to produce planetesimals. However, these investigations have been limited to small-scale simulations. We now present the results of a global protoplanetary disk evolution model that incorporates planetesimal formation by the streaming instability, along with viscous accretion, photoevaporation by EUV, FUV, and X-ray photons, dust evolution, the water ice line, and stratified turbulence. Our simulations produce massive (60-130 $M_\oplus$) planetesimal belts beyond 100 au and up to $\sim 20 M_\oplus$ of planetesimals in the middle regions (3-100 au). Our most comprehensive model forms 8 $M_\oplus$ of planetesimals inside 3 au, where they can give rise to terrestrial planets. The planetesimal mass formed in the inner disk depends critically on the timing of the formation of an inner cavity in the disk by high-energy photons. Our results show that the combination of photoevaporation and the streaming instability are efficient at converting the solid component of protoplanetary disks into planetesimals. Our model, however, does not form enough early planetesimals in the inner and middle regions of the disk to give rise to giant planets and super-Earths with gaseous envelopes. Additional processes such as particle pileups and mass loss driven by MHD winds may be needed to drive the formation of early planetesimal generations in the planet forming regions of protoplanetary disks.