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Nonlinear wave propagation and reconnection at magnetic X-points in the Hall MHD regime
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Threlfall, J., Parnell, C. E., De Moortel, I., McClements, K. G. and Arber, T. D. (2012) Nonlinear wave propagation and reconnection at magnetic X-points in the Hall MHD regime. Astronomy & Astrophysics, Volume 544 . Article number A24. doi:10.1051/0004-6361/201219098 ISSN 0004-6361.
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Official URL: http://dx.doi.org/10.1051/0004-6361/201219098
Abstract
Context.
The highly dynamical, complex nature of the solar atmosphere naturally implies the presence of waves in a topologically varied magnetic environment. Here, the interaction of waves with topological features such as null points is inevitable and potentially important for energetics. The low resistivity of the solar coronal plasma implies that non-magnetohydrodynamic (MHD) effects should be considered in studies of magnetic energy release in this environment.
Aims.
This paper investigates the role of the Hall term in the propagation and dissipation of waves, their interaction with 2D magnetic X-points and the nature of the resulting reconnection.
Methods.
A Lagrangian remap shock-capturing code (Lare2d) was used to study the evolution of an initial fast magnetoacoustic wave annulus for a range of values of the ion skin depth (δi) in resistive Hall MHD. A magnetic null-point finding algorithm was also used to locate and track the evolution of the multiple null-points that are formed in the system.
Results.
Depending on the ratio of ion skin depth to system size, our model demonstrates that Hall effects can play a key role in the wave-null interaction. In particular, the initial fast-wave pulse now consists of whistler and ion-cyclotron components; the dispersive nature of the whistler wave leads to (i) earlier interaction with the null; (ii) the creation of multiple additional, transient nulls and, hence, an increased number of energy release sites. In the Hall regime, the relevant timescales (such as the onset of reconnection and the period of the oscillatory relaxation) of the system are reduced significantly, and the reconnection rate is enhanced.
Item Type: | Journal Article | ||||||||||||
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Subjects: | Q Science > QB Astronomy | ||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||||||
Library of Congress Subject Headings (LCSH): | Magnetohydrodynamics, Magnetic reconnection, Sun -- Corona, Solar flares | ||||||||||||
Journal or Publication Title: | Astronomy & Astrophysics | ||||||||||||
Publisher: | EDP Sciences | ||||||||||||
ISSN: | 0004-6361 | ||||||||||||
Official Date: | 2012 | ||||||||||||
Dates: |
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Volume: | Volume 544 | ||||||||||||
Article Number: | Article number A24 | ||||||||||||
DOI: | 10.1051/0004-6361/201219098 | ||||||||||||
Status: | Peer Reviewed | ||||||||||||
Publication Status: | Published | ||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | ||||||||||||
Date of first compliant deposit: | 24 April 2018 | ||||||||||||
Date of first compliant Open Access: | 24 April 2018 | ||||||||||||
RIOXX Funder/Project Grant: |
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