The dynamical structure of HR 8799's inner debris disk

TL;DR

This study uses extensive simulations to characterize the inner debris disk of HR 8799, revealing its structure and potential implications for planet formation and water delivery in the system.

Contribution

It provides the most detailed dynamical modeling of HR 8799's inner debris disk to date, improving understanding of its extent and structure.

Findings

Detailed structure of HR 8799's inner debris disk characterized

Simulations suggest potential impact rates on hypothetical terrestrial planets

Insights into water delivery prospects for inner planets

Abstract

The HR 8799 system, with its four giant planets and two debris belts, has an architecture closely mirroring that of our Solar system where the inner, warm asteroid belt and outer, cool Edgeworth-Kuiper belt bracket the giant planets. As such, it is a valuable laboratory for examining exoplanetary dynamics and debris disk-exoplanet interactions. Whilst the outer debris belt of HR 8799 has been well resolved by previous observations, the spatial extent of the inner disk remains unknown. This leaves a significant question mark over both the location of the planetesimals responsible for producing the belt's visible dust and the physical properties of those grains. We have performed the most extensive simulations to date of the inner, unresolved debris belt around HR 8799, using UNSW Australia's Katana supercomputing facility to follow the dynamical evolution of a model inner disk comprising 300,298 particles for a period of 60 million years. These simulations have enabled the characterisation of the extent and structure of the inner disk in detail, and will in future allow us to provide a first estimate of the small-body impact rate and water delivery prospects for possible (as-yet undetected) terrestrial planet(s) in the inner system.