The Dead Zones of Protoplanetary Disks are Not Dead

We show that the "dead" zone of a protoplanetary disk fills with robust 3D vortices from a purely hydrodynamic instability. This new instability is not linear and requires a weak finite-amplitude initial perturbation. The instability was not seen previously either due to a lack of numerica...

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Bibliographic Details
Published in:EPJ Web of conferences 2013-01, Vol.46, p.3006-03006
Main Authors: Marcus, Philip S., Jiang, Chung-Hsiang, Pei, Suyang, Hassanzadeh, Pedram
Format: Article
Language:English
Subjects:
Disks
Excitation
Fluid flow
Instability
Planet formation
Protoplanets
Stability
Vortices
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Summary:We show that the "dead" zone of a protoplanetary disk fills with robust 3D vortices from a purely hydrodynamic instability. This new instability is not linear and requires a weak finite-amplitude initial perturbation. The instability was not seen previously either due to a lack of numerical spatial resolution, or because many previous simulations either ignored vertical gravity or had initial flows with constant density. Our new finite-amplitude instability is due to a family of previously-unknown critical layers that form in rotating, shearing, vertically stratified flows like those in protoplanetary disks. Initial perturbations of white noise (with Mach numbers much less than unity), waves, or vortices can trigger the instability. A small-volume, small-amplitude initial vortex confined to one part of the disk can fill the disk with vortices by exciting a nearby critical layer. The critical layer produces an intense vortex layer that rolls-up to form vortices with large-amplitudes and volumes. This 1 super(s)tgeneration of vortices then sheds waves that excite nearby critical layers, which in turn, create a 2 super(n)dgeneration of vortices with large amplitudes and volumes. The mechanism of exciting nearby critical layers and turning them into large vortices self-similarly, self-replicates until large vortices fill the disk at all radii.
ISSN:2100-014X
2100-014X
DOI:10.1051/epjconf/20134603006