Collision rates of planetesimals near mean-motion resonances
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In circumstellar discs, collisional grinding of planetesimals produces second-generation dust which can be observed through thermal emission. While it remains unclear when second- generation dust first becomes a major component of the total dust content, the presence of such dust and potentially the substructure within it can be used to explore a disc’s physical conditions. A perturbing planet has been shown to produce nonaxisymmetric structures, as well as gaps in discs, regardless of the origin of the dust. However, small grains will have very different dynamics compared with planetesimals when in the presence of gas, and as such, the collisional evolution of planetesimals could create dusty disc structures that would not exist otherwise. Previous studies have shown that morphological differences in the collisional dust corotating with a giant planet can be used to determine whether the planet’s eccentricity is large or small. Going further, we investigate the production of second-generation dust near prominent mean-motion resonances with the planet using N-body simulations that directly resolve collisions between planetesimals. We find that a distinct over- or under-density in the dust emission is produced at the interior 2:1 mean-motion resonance, depending on the mass and eccentricity of the planet. The presence of one of these two features can be used to place simultaneous upper or lower limits on the mass and eccentricity of the perturbing body.
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