Constraining the Planetary System of Fomalhaut Using High-Resolution ALMA Observations

TL;DR

This paper presents high-resolution ALMA observations of Fomalhaut's debris ring, revealing its narrow width and sharp boundaries, and discusses possible origins including shepherd planets.

Contribution

The study provides the first high-resolution ALMA imaging of Fomalhaut's debris ring, constraining its width, boundaries, and potential formation mechanisms.

Findings

Ring is 13-19 AU wide with sharp boundaries

Debris likely confined by shepherd planets

Supports planetary influence on debris morphology

Abstract

The dynamical evolution of planetary systems leaves observable signatures in debris disks. Optical images trace micron-sized grains, which are strongly affected by stellar radiation and need not coincide with their parent body population. Observations of mm-size grains accurately trace parent bodies, but previous images lack the resolution and sensitivity needed to characterize the ring's morphology. Here we present ALMA 350 GHz observations of the Fomalhaut debris ring. These observations demonstrate that the parent body population is 13-19 AU wide with a sharp inner and outer boundary. We discuss three possible origins for the ring, and suggest that debris confined by shepherd planets is the most consistent with the ring's morphology.