Debris discs in binaries: a numerical study

Abstract

Debris disc analysis and modelling provide crucial information about the structure and the processes at play in extrasolar planetary systems. In binary systems, this issue is more complex because the disc should in addition respond to the companion star's perturbations. We explore the dynamical evolution of a collisionally active debris disc for different initial parent body populations, diverse binary configurations and optical depths. We focus on the radial extent and size distribution of the disc at a stationary state. We numerically follow the evolution of $10^5$ massless small grains, initially produced from a circumprimary disc of parent bodies following a size distribution in $dN\propto s^{-3.5}$ds . Grains are submitted to both stars' gravity as well as radiation pressure. In addition, particles are assigned an empirically derived collisional lifetime. For all the binary configurations the disc extends far beyond the critical semimajor axis $a_{c}rit$ for orbital stability. This is due to the steady production of small grains, placed on eccentric orbits reaching beyond $a_{c}rit$ by radiation pressure. The amount of matter beyond acrit depends on the balance between collisional production and dynamical removal rates: it increases for more massive discs as well as for eccentric binaries. Another important effect is that, in the dynamically stable region, the disc is depleted from its smallest grains. Both results could lead to observable signatures. We have shown that a companion star can never fully truncate a collisionally active disc. For eccentric companions, grains in the unstable regions can significantly contribute to the thermal emission in the mid-IR. Discs with sharp outer edges, especially bright ones such as HR4796A, are probably shaped by other mechanisms.

accepted for publication in A&A

References in corpus (12)

• Optical Images of an Exosolar Planet 25 Light Years from Earth
• Properties of planets in binary systems. The role of binary separation
• Long-Term Collisional Evolution of Debris Disks
• Collisional processes and size distribution in spatially extended debris discs
• Relative velocities among accreting planetesimals in binary systems: the circumprimary case
• STIS Imaging of the HR 4796A Circumstellar Debris Ring
• Outer edges of debris discs: how sharp is sharp?
• Planetesimal and gas dynamics in binaries
• iVINE - Ionization in the parallel tree/SPH code VINE: First results on the observed age-spread around O-stars
• The multiplicity of exoplanet host stars - New low-mass stellar companions of the exoplanet host stars HD125612 and HD212301
• Investigating the flyby scenario for the HD 141569 system
• Planetesimal Accretion in Binary Systems: The Effects of Gas Dissipation

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• Self-Stirring of Debris Discs by Planetesimals Formed by Pebble Concentration
• The HR 4796A Debris System: Discovery of Extensive Exo-Ring Dust Material
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• The Gemini NICI Planet-Finding Campaign: The Offset Ring of HR 4796 A
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