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Dust-vortex Instability in the Regime of Well-coupled Grains


Surville, Clément; Mayer, Lucio (2019). Dust-vortex Instability in the Regime of Well-coupled Grains. The Astrophysical Journal, 883(2):176.

Abstract

We present a novel study of dust-vortex evolution in global two-fluid disk simulations to find out if evolution toward high dust-to-gas ratios can occur in a regime of well-coupled grains with low Stokes numbers (St = 10−3 − 4 × 10−2). We design a new implicit scheme in the code RoSSBi, to overcome the short time-steps occurring for small grain sizes. We discover that the linear capture phase occurs self-similarly for all grain sizes, with an intrinsic timescale (characterizing the vortex lifetime) scaling as 1/St. After vortex dissipation, the formation of a global active dust ring is a generic outcome confirming our previous results obtained for larger grains. We propose a scenario in which, regardless of grain size, multiple pathways can lead to local dust-to-gas ratios of about unity and above on relatively short timescales, <105 yr, in the presence of a vortex, even with St = 10−3. When St > 10−2, the vortex is quickly dissipated by two-fluid instabilities, and large dust density enhancements form in the global dust ring. When St < 10−2, the vortex is resistant to destabilization. As a result, dust concentrations occur locally due to turbulence developing inside the vortex. Regardless of the Stokes number, dust-to-gas ratios in the range 1–10, a necessary condition to trigger a subsequent streaming instability, or even a direct gravitational instability of the dust clumps, appears to be an inevitable outcome. Although quantitative connections with other instabilities still need to be made, we argue that our results support a new scenario of vortex-driven planetesimal formation.

Abstract

We present a novel study of dust-vortex evolution in global two-fluid disk simulations to find out if evolution toward high dust-to-gas ratios can occur in a regime of well-coupled grains with low Stokes numbers (St = 10−3 − 4 × 10−2). We design a new implicit scheme in the code RoSSBi, to overcome the short time-steps occurring for small grain sizes. We discover that the linear capture phase occurs self-similarly for all grain sizes, with an intrinsic timescale (characterizing the vortex lifetime) scaling as 1/St. After vortex dissipation, the formation of a global active dust ring is a generic outcome confirming our previous results obtained for larger grains. We propose a scenario in which, regardless of grain size, multiple pathways can lead to local dust-to-gas ratios of about unity and above on relatively short timescales, <105 yr, in the presence of a vortex, even with St = 10−3. When St > 10−2, the vortex is quickly dissipated by two-fluid instabilities, and large dust density enhancements form in the global dust ring. When St < 10−2, the vortex is resistant to destabilization. As a result, dust concentrations occur locally due to turbulence developing inside the vortex. Regardless of the Stokes number, dust-to-gas ratios in the range 1–10, a necessary condition to trigger a subsequent streaming instability, or even a direct gravitational instability of the dust clumps, appears to be an inevitable outcome. Although quantitative connections with other instabilities still need to be made, we argue that our results support a new scenario of vortex-driven planetesimal formation.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Scopus Subject Areas:Physical Sciences > Astronomy and Astrophysics
Physical Sciences > Space and Planetary Science
Uncontrolled Keywords:Space and Planetary Science, Astronomy and Astrophysics
Language:English
Date:3 October 2019
Deposited On:14 Feb 2020 08:25
Last Modified:29 Jul 2020 13:42
Publisher:IOP Publishing
ISSN:1538-4357
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.3847/1538-4357/ab3e47

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