Alignment and Rotational Disruption of Dust

We reveal a deep connection between alignment of dust grains by radiative torques (RATs) and mechanical torques (METs) and the rotational disruption of grains introduced by Hoang et al. The disruption of grains happens if they have attractor points corresponding to high angular momentum (high J). We...

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Bibliographic Details
Published in:The Astrophysical journal 2021-02, Vol.908 (1), p.12
Main Authors: Lazarian, A., Hoang, Thiem
Format: Article
Language:English
Subjects:
Alignment
Angular momentum
Astrochemistry
Astrophysics
Astrosphere interstellar medium interactions
Collisions
Disruption
Dust
Efficiency
Gas density
Inclusions
Interstellar dust
Interstellar dust extinction
Interstellar dust processes
Interstellar medium
Magnetic fields
Magnetic permeability
Starlight polarization
Torque
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Summary:We reveal a deep connection between alignment of dust grains by radiative torques (RATs) and mechanical torques (METs) and the rotational disruption of grains introduced by Hoang et al. The disruption of grains happens if they have attractor points corresponding to high angular momentum (high J). We introduce fast disruption for grains that are directly driven to the high-J attractor on a timescale of spin-up, and slow disruption for grains that are first moved to the low-J attractor and gradually transported to the high-J attractor by gas collisions. The enhancement of grain magnetic susceptibility by iron inclusions expands the parameter space for high-J attractors and increases the percentage of grains experiencing the disruption. The increase in the magnitude of RATs or METs can increase the efficiency of fast disruption but, counterintuitively, decreases the effect of slow disruption by forcing grains toward low-J attractors, whereas the increase in gas density accelerates disruption by transporting grains faster to the high-J attractor. We also show that the disruption induced by RATs and METs depends on the angle between the magnetic field and the anisotropic flow. We find that pinwheel torques can increase the efficiency of fast disruption but may decrease the efficiency of slow disruption by delaying the transport of grains from the low-J to high-J attractors via gas collisions. The selective nature of the rotational disruption opens a possibility of observational testing of grain composition and physical processes of grain alignment.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/abd02c