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The acoustic resonant drag instability with a spectrum of grain sizes

Squire, Jonathan and Moroianu, Stefania and Hopkins, Philip F. (2022) The acoustic resonant drag instability with a spectrum of grain sizes. Monthly Notices of the Royal Astronomical Society, 510 (1). pp. 110-130. ISSN 0035-8711. doi:10.1093/mnras/stab3377.

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We study the linear growth and non-linear saturation of the ‘acoustic Resonant Drag Instability’ (RDI) when the dust grains, which drive the instability, have a wide, continuous spectrum of different sizes. This physics is generally applicable to dusty winds driven by radiation pressure, such as occurs around red-giant stars, star-forming regions, or active galactic nuclei. Depending on the physical size of the grains compared to the wavelength of the radiation field that drives the wind, two qualitatively different regimes emerge. In the case of grains that are larger than the radiation’s wavelength – termed the constant-drift regime – the grain’s equilibrium drift velocity through the gas is approximately independent of grain size, leading to strong correlations between differently sized grains that persist well into the saturated non-linear turbulence. For grains that are smaller than the radiation’s wavelength – termed the non-constant-drift regime – the linear instability grows more slowly than the single-grain-size RDI and only the larger grains exhibit RDI-like behaviour in the saturated state. A detailed study of grain clumping and grain–grain collisions shows that outflows in the constant-drift regime may be effective sites for grain growth through collisions, with large collision rates but low collision velocities.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper ItemGIZMO code
Squire, Jonathan0000-0001-8479-962X
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2021 November 16. Received 2021 November 15; in original form 2021 June 29. We thank Eric Moseley and Darryl Seligman for helpful discussion. Support for JS was provided by Rutherford Discovery Fellowship RDF-U001804 and Marsden Fund grant UOO1727, which are managed through the Royal Society Te Apārangi. Support for JS, PFH, and SM was provided by NSF Collaborative Research Grants 1715847 and 1911233, NSF CAREER grant 1455342, and NASA grants 80NSSC18K0562 and JPL 1589742. Numerical simulations were run on the Caltech compute cluster ‘Wheeler,’ and with allocation TG-AST130039 from the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant number ACI-1548562. DATA AVAILABILITY. The simulation data presented in this article is available on request to JS. A public version of the GIZMO code is available at
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
Royal Society Te ApārangiRDF-U001804
Royal Society Te ApārangiUOO1727
Marsden Fund of the Royal Society of New ZealandUNSPECIFIED
Subject Keywords:instabilities, turbulence, stars: winds, outflows, dust, extinction, ISM: kinematics and dynamics, galaxies: formation
Issue or Number:1
Record Number:CaltechAUTHORS:20220228-619611000
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Official Citation:Jonathan Squire, Stefania Moroianu, Philip F Hopkins, The acoustic resonant drag instability with a spectrum of grain sizes, Monthly Notices of the Royal Astronomical Society, Volume 510, Issue 1, February 2022, Pages 110–130,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113629
Deposited By: George Porter
Deposited On:01 Mar 2022 19:01
Last Modified:01 Mar 2022 19:01

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