Vertical structure of debris discs

Abstract

The vertical thickness of debris discs is often used as a measure of these systems' dynamical excitation and as clues to the presence of hidden massive perturbers such as planetary embryos. However, this argument could be flawed because the observed dust should be naturally placed on inclined orbits by the combined effect of radiation pressure and mutual collisions. We critically reinvestigate this issue and numerically estimate what the "natural" vertical thickness of a collisionally evolving disc is, in the absence of any additional perturbing body. We use a deterministic collisional code, following the dynamical evolution of a population of indestructible test grains suffering mutual inelastic impacts. Grain differential sizes as well as the effect of radiation pressure are taken into account. We find that, under the coupled effect of radiation pressure and collisions, grains naturally acquire inclinations of a few degrees. The disc is stratified with respect to grain sizes, with the smallest grains having the largest vertical dispersion and the bigger ones clustered closer to the midplane. Debris discs should have a minimum "natural" observed aspect ratio $h_{min}\sim 0.04\pm 0.02$ at visible to mid-IR wavelengths where the flux is dominated by the smallest bound grains. These values are comparable to the estimated thicknesses of many vertically resolved debris discs, as is illustrated with the specific example of AU Mic. For all systems with $h\sim h_{min}$, the presence (or absence) of embedded perturbing bodies cannot be inferred from the vertical dispersion of the disc

accepted for publication in Astronomy and Astrophysics (full abstract in the pdf file)

References in corpus (13)

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• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
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• Discovery of an 86 AU Radius Debris Ring Around HD 181327
• Outer edges of debris discs: how sharp is sharp?
• Discovery of extreme asymmetry in the debris disk surrounding HD 15115
• First scattered light images of debris disks around HD 53143 and HD 139664
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Cited by in corpus (59)

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• The Mass of Stirring Bodies in the AU Mic Debris Disk Inferred from Resolved Vertical Structure
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• HD 104860 and HD 192758: two debris disks newly imaged in scattered-light with HST
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• Multiwavelength Vertical Structure in the AU Mic Debris Disk: Characterizing the Collisional Cascade
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• Debris Disks in Multi-Planet Systems: Are Our Inferences Compromised by Unseen Planets?
• Toward a Population Synthesis of Disks and Planets I. Evolution of Dust with Entrainment in Winds and Radiation Pressure
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• The vertical structure of debris discs and the role of disc gravity: A primer using a simplified model
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• Herschel Observations and Updated Spectral Energy Distributions of Five Sunlike Stars with Debris Disks
• First resolved observations of a highly asymmetric debris disc around HD 160305 with VLT/SPHERE
• High resolution ALMA and HST imaging of $\kappa$CrB: a broad debris disc around a post-main sequence star with low-mass companions
• The ALMA survey to Resolve exoKuiper belt Substructures (ARKS) III: The vertical structure of debris disks
• Characterization of debris disks observed with SPHERE
• Water ice in the debris disk around HD 181327
• Narrow belt of debris around the Sco-Cen star HD 141011
• Millimeter Dust Emission and Planetary Dynamics in the HD 106906 System
• Absorption of crystalline water ice in the far infrared at different temperatures
• Stellar winds can affect gas dynamics in debris disks and create observable belt winds
• Collisional damping in debris discs: Only significant if collision velocities are low
• ALMA's view of the M-dwarf GSC 07396-00759's edge-on debris disc: AU Mic's coeval twin
• Quadrant polarization parameters for the scattered light of circumstellar disks. Analysis of debris disk models and observations of HR 4796A
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• The first scattered light images of HD 112810, a faint debris disk in the Sco-Cen association
• Testing the Impact of Planet-stirring, Self-stirring, and Mixed-stirring on Debris Disc Architecture: A Case Study of HD 16743
• The Longest-period Young Transiting Exoplanets. A Duo of Puffy Giants inside a Debris Disk