Debris disc formation induced by planetary growth

Abstract

Several hundred stars older than 10 million years have been observed to have infrared excesses. These observations are explained by dust grains formed by the collisional fragmentation of hidden planetesimals. Such dusty planetesimal discs are known as debris discs. In a dynamically cold planetesimal disc, collisional coagulation of planetesimals produces planetary embryos which then stir the surrounding leftover planetesimals. Thus, the collisional fragmentation of planetesimals that results from planet formation forms a debris disc. We aim to determine the properties of the underlying planetesimals in debris discs by numerically modelling the coagulation and fragmentation of planetesimal populations. The brightness and temporal evolution of debris discs depend on the radial distribution of planetesimal discs, the location of their inner and outer edges, their total mass, and the size of planetesimals in the disc. We find that a radially narrow planetesimal disc is most likely to result in a debris disc that can explain the trend of observed infrared excesses of debris discs around G-type stars, for which planet formation occurs only before 100 million years. Early debris disc formation is induced by planet formation, while the later evolution is explained by the collisional decay of leftover planetesimals around planets that have already formed. Planetesimal discs with underlying planetesimals of radii $\sim 100$km at $\approx 30$ AU most readily explain the Spitzer Space Telescope 24 and 70$\mu$m fluxes from debris discs around G-type stars.

10 pages, 11 figures; accepted for publication in MNRAS

References in corpus (5)

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• The Complete Census of 70-um-Bright Debris Disks within the FEPS (Formation and Evolution of Planetary Systems) Spitzer Legacy Survey of Sun-like Stars
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Cited by in corpus (9)

• Five steps in the evolution from protoplanetary to debris disk
• Solution to the debris disc mass problem: planetesimals are born small?
• The SHARDDS survey: first resolved image of the HD114082 debris disk in Lower Centaurus Crux with SPHERE
• Debris Disc Constraints on Planetesimal Formation
• Formation of Super-Earth Mass Planets at 125-250 AU from a Solar-type Star
• Inner edges of planetesimal belts: collisionally eroded or truncated?
• Importance of Giant Impact Ejecta for Orbits of Planets Formed during the Giant Impact Era
• A Constraint on the Amount of Hydrogen from the CO Chemistry in Debris Disks
• Takeout and Delivery: Erasing the Dusty Signature of Late-stage Terrestrial Planet Formation