Collisional processes and size distribution in spatially extended debris discs

Abstract

We present a new multi-annulus code for the study of collisionally evolving extended debris discs. We first aim to confirm results obtained for a single-annulus system, namely that the size distribution in "real" debris discs always departs from the theoretical collisional equilibrium $dN\proptoR^{-3.5}dR$ power law, especially in the crucial size range of observable particles (<1cm), where it displays a characteristic wavy pattern. We also aim at studying how debris discs density distributions, scattered light luminosity profiles, and SEDs are affected by the coupled effect of collisions and radial mixing due to radiation pressure affected small grains. The size distribution evolution is modeled from micron-sized grains to 50km-sized bodies. The model takes into account the crucial influence of radiation pressure-affected small grains. We consider the collisional evolution of a fiducial a=120AU radius disc with an initial surface density in $\Sigma (a)\propto a^{\alpha }$. We show that the system's radial extension plays a crucial role: in most regions the collisional and size evolution of the dust is imposed by small particles on eccentric or unbound orbits produced further inside the disc. The spatial distribution of small grains strongly departs from the initial profile, while the bigger objects, containing most of the system's mass, still follow the initial distribution. This has consequences on the scattered--light radial profiles which get significantly flatter, and we propose an empirical law to trace back the distribution of large unseen parent bodies from the observed profiles. We finally provide empirical formula for the collisional size distribution and collision timescale that can be used for future debris disc modeling.

Accepted for publication in Astronomy and Astrophysics (with better figures) (note: full abstract in the *.pdf file)

References in corpus (4)

• HST/ACS Multiband Coronagraphic Imaging of the Debris Disk around Beta Pictoris
• Discovery of an 86 AU Radius Debris Ring Around HD 181327
• First scattered light images of debris disks around HD 53143 and HD 139664
• Collisional dust avalanches in debris discs

Cited by in corpus (14)

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• Formation and Evolution of Planetary Systems (FEPS): Properties of Debris Dust around Solar-type Stars
• Long-Term Collisional Evolution of Debris Disks
• Outer edges of debris discs: how sharp is sharp?
• Survival of icy grains in debris discs. The role of photosputtering
• Planet formation in Alpha Centauri A revisited: not so accretion-friendly after all
• Collisional and Thermal Emission Models of Debris Disks: Towards Planetesimal Population Properties
• Long-wavelength observations of debris discs around sun-like stars
• Planetesimal Accretion in Binary Systems: The Effects of Gas Dissipation
• A Possible Icy Kuiper Belt around HD 181327
• q1 Eri: a solar-type star with a planet and a dust belt
• A Resolved Ring of Debris Dust Around the Solar Analog HD 107146
• Discovery of an extended debris disk around the F2V star HD 15745