Size and density sorting of dust grains in SPH simulations of protoplanetary discs – II. Fragmentation

Abstract

Grain growth and fragmentation are important processes in building up large dust aggregates in protoplanetary discs. Using a 3D two-phase (gas-dust) SPH code, we investigate the combined effects of growth and fragmentation of a multi-phase dust with different fragmentation thresholds in a time-evolving disc. We find that our fiducial disc, initially in a fragmentation regime, moves toward a pure-growth regime in a few thousands years. Timescales change as a function of the disc and dust properties. When fragmentation is efficient, it produces, in different zones of the disc, Fe/Si and rock/ice ratios different from those predicted when only pure growth is considered. Chemical fractionation and the depletion/enrichment in iron observed in some chondrites can be linked to the size-density sorting and fragmentation properties of precursor dusty grains . We suggest that aggregation of chondritic components could have occurred where/when fragmentation was not efficient if their aerodynamical sorting has to be preserved. Chondritic components would allow aerodynamical sorting in a fragmentation regime only if they have similar fragmentation properties. We find that, in the inner disc, and for the same interval of time, fragmenting dust can grow larger when compared to the size of grains predicted by pure growth. This counter-intuitive behaviour is due to the large amount of dust which piles up in a fragmenting zone followed by the rapid growth that occurs when this zone transitions to a pure growth regime. As an important consequence, dust can overcome the radial-drift barrier within a few thousands years.

Self-induced dust traps around snow lines in protoplanetary discs

“…The disc model parameters are given in Table 1. Resolution studies with our code have shown convergence with fewer particles (Barrière- Fouchet et al 2005;Fouchet et al 2007;Pignatale et al 2019). Additionally, the resolution criterion proposed by is met in our simulations.…”

Dust growth, fragmentation and self-induced dust traps in PHANTOM

“…With this comparison, we are confident that the mechanism observed is a self-induced dust trap. Although this mechanism has been observed several times (Gonzalez et al 2017a;Garcia 2018;Pignatale et al 2019;Vericel & Gonzalez 2020), this is the first time it is observed in another, independent code, which validates its existence. A faceon rendered view of the gas and dust density evolution during the self-induced dust trap formation is shown in Fig.…”

Evolution of porous dust grains in protoplanetary discs – I. Growing grains

“…Previous work with the same code (e.g. Barrière-Fouchet et al 2005;Fouchet et al 2007;Pignatale et al 2019) has shown that convergence is reached at lower particle numbers. We also verify that the resolution criterion from Laibe & Price (2012) is met.…”