Second-generation dust in planetary systems: The case of HD 163296

Abstract

Observations indicate that large, dust-laden protoplanetary discs are common. Some features, like gaps, rings and spirals, suggest they may host young planets, which can excite the orbits of nearby leftover planetesimals. Energetic collisions among these bodies can lead to the production of second-generation dust. Grains produced by collisions may have a dynamical behaviour different from that of first-generation, primordial dust out of which planetesimals and planets formed. We aim to study these differences for the HD 163296 system and determine whether dynamical signatures in the mixture of the two dust populations can help separate their contributions. We use three-dimensional (3-D) hydrodynamic models to describe the gaseous disc with three, Saturn- to Jupiter-mass, embedded planets. Dust grains, of sizes 1um-1mm, are treated as Lagrangean particles with resolved thermodynamics and mass loss. Initial disc and planet configurations are derived from observation-based work, which indicates low gas viscosity. The 3-D approach also allows us to detect the formation of vortices induced by Rossby waves, where dust becomes concentrated and may contribute to planetesimal formation. We find that the main differences in the dynamical behaviour of first- and second-generation dust occur in the vertical distribution. The two populations have similar distributions around the disc mid-plane, although second-generation dust shows longer residence times close to the radial locations of the planets' gas gaps. Sedimentation rates of um-size grains are comparable to or lower than the production rates by planetesimals' collisions, making this population potentially observable. These outcomes can be extended to similar systems harbouring giant planets.

13 pages, 1 table, 13 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal

References in corpus (7)

• The HD 163296 Circumstellar Disk in Scattered Light: Evidence of Time-Variable Self-Shadowing
• Long Term Evolution of Planet-Induced Vortices in Protoplanetary Disks
• Rossby Wave Instability in three dimensional discs
• Midplane temperature and outer edge of the protoplanetary disk around HD 163296
• Radial variations in grain sizes and dust scale heights in the protoplanetary disk around HD 163296 revealed by ALMA polarization observation
• Determining mass limits around HD163296 through SPHERE direct imaging data
• Circumstellar dust distribution in systems with two planets in resonance

Cited by in corpus (4)

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• A broken debris cascade as a possible source of hot dust emission in transitioning planet-forming disks
• Effects of turbulent diffusion and back-reaction on the dust distribution around two resonant planets
• A planet or primordial black hole in the outer region of the Solar system and the dust flow near Earth orbit