A second planetesimal collision in the Fomalhaut system

TL;DR

This paper reports the discovery of a second dust cloud around Fomalhaut, likely caused by a recent planetesimal collision, providing insights into the collisional dynamics within its debris belt.

Contribution

It presents the first direct observation of a second impact-generated dust cloud in the Fomalhaut system, revealing ongoing collisional activity.

Findings

Detection of a second dust cloud around Fomalhaut in 2023

Constraints on collisional dynamics from dust cloud motions over 20 years

Evidence supporting recent planetesimal collisions in the debris belt

Abstract

The nearby star Fomalhaut is orbited by a compact source, Fomalhaut b, which has previously been interpreted as either a dust-enshrouded exoplanet or a dust cloud generated by the collision of two planetesimals. Such collisions are rarely observed but their debris can appear in direct imaging. We report Hubble Space Telescope observations that show the appearance in 2023 of a second point source around Fomalhaut, resembling the appearance of Fomalhaut b twenty years earlier. We interpret this additional source as a dust cloud produced by a recent impact between two planetesimals. The positions and motion of two impact-generated dust clouds over twenty years provide constraints on the collisional dynamics in the debris belt.