Nonlinear fast magnetoacoustic wave propagation in the neighbourhood of a 2D magnetic X-point : oscillatory reconnection
McLaughlin, J. A. (James A.), Moortel, I. de, Hood, Alan W. and Brady, Christopher S.. (2009) Nonlinear fast magnetoacoustic wave propagation in the neighbourhood of a 2D magnetic X-point : oscillatory reconnection. Astronomy & Astrophysics, Vol.493 (No.1). pp. 227-240. ISSN 0004-6361
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Official URL: http://dx.doi.org/10.1051/0004-6361:200810465
Context. This paper extends the models of Craig & McClymont (1991, ApJ, 371, L41) and McLaughlin & Hood (2004, A&A, 420,
1129) to include finite β and nonlinear effects.
Aims. We investigate the nature of nonlinear fast magnetoacoustic waves about a 2D magnetic X-point.
Methods. We solve the compressible and resistive MHD equations using a Lagrangian remap, shock capturing code (Arber et al. 2001, J. Comp. Phys., 171, 151) and consider an initial condition in u × B · ˆz (a natural variable of the system).
Results. We observe the formation of both fast and slow oblique magnetic shocks. The nonlinear wave deforms the X-point into a “cusp-like” point which in turn collapses to a current sheet. The system then evolves through a series of horizontal and vertical current sheets, with associated changes in connectivity, i.e. the system exhibits oscillatory reconnection. Our final state is non-potential (but in force balance) due to asymmetric heating from the shocks. Larger amplitudes in our initial condition correspond to larger values of the final current density left in the system.
Conclusions. The inclusion of nonlinear terms introduces several new features to the system that were absent from the linear regime.
|Item Type:||Journal Article|
|Subjects:||Q Science > QB Astronomy|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Magnetohydrodynamics , Nonlinear waves, Nonlinear acoustics, Sun -- Corona -- Magnetic fields, Sun -- Corona -- Mathematical models, Solar oscillations|
|Journal or Publication Title:||Astronomy & Astrophysics|
|Official Date:||January 2009|
|Page Range:||pp. 227-240|
|Access rights to Published version:||Open Access|
|Funder:||Royal Society (Great Britain), Leverhulme Trust (LT), Science and Technology Facilities Council (Great Britain) (STFC), Scottish Funding Council (SFC)|
Arber, T. D., Longbottom, A.W., Gerrard, C. L., &Milne, A. M. 2001, J. Comp.
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