Shaping HR8799's outer dust belt with an unseen planet

Abstract

HR8799 is a benchmark system for direct imaging studies. It hosts two debris belts, which lie internally and externally to four giant planets. This paper considers how the four known planets and a possible fifth planet, interact with the external population of debris through N-body simulations. We find that when only the known planets are included, the inner edge of the outer belt predicted by our simulations is much closer to the outermost planet than recent ALMA observations suggest. We subsequently include a fifth planet in our simulations with a range of masses and semi-major axes, which is external to the outermost known planet. We find that a fifth planet with a mass and semi-major axis of 0.1${\mathrm{M}}_{\mathrm{J}}$ and 138au predicts an outer belt that agrees well with ALMA observations, whilst remaining stable for the lifetime of HR8799 and lying below current direct imaging detection thresholds. We also consider whether inward scattering of material from the outer belt can input a significant amount of mass into the inner belt. We find that for the current age of HR8799, only $\sim$1\% of the mass loss rate of the inner disk can be replenished by inward scattering. However we find that the higher rate of inward scattering during the first $\sim$10Myr of HR8799 would be expected to cause warm dust emission at a level similar to that currently observed, which may provide an explanation for such bright emission in other systems at $\sim 10$Myr ages.

16 pages, 13 figures. Accepted for publication in MNRAS

References in corpus (13)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Transience of hot dust around sun-like stars
• Spitzer IRS Spectroscopy of IRAS-Discovered Debris Disks
• Discovery of a warm, dusty giant planet around HIP65426
• Reconnaissance of the HR 8799 Exosolar System II: Astrometry and Orbital Motion
• Planetary chaotic zone clearing: destinations and timescales
• The CORALIE survey for southern extrasolar planets XVII. New and updated long period and massive planets
• Debris Distribution in HD 95086 - A Young Analog of HR 8799
• Resolved debris disk emission around eta Tel: a young Solar System or ongoing planet formation?
• The LEECH Exoplanet Imaging Survey. Further constraints on the planet architecture of the HR 8799 system
• Perturbation of Compact Planetary Systems by Distant Giant Planets
• The unseen planets of double belt debris disk systems
• Long-term stability of the HR 8799 planetary system without resonant lock

Cited by in corpus (6)

• Planet populations inferred from debris discs: insights from 178 debris systems in the ISPY, LEECH and LIStEN planet-hunting surveys
• A gap in HD 92945's broad planetesimal disc revealed by ALMA
• Constraining planetesimal stirring: how sharp are debris disc edges?
• Inner edges of planetesimal belts: collisionally eroded or truncated?
• Pebble accretion in self-gravitating protostellar discs
• Enrichment of the HR 8799 planets by minor bodies and dust