Dr Christopher Prior christopher.prior@durham.ac.uk
Associate Professor
Twisted versus braided magnetic flux ropes in coronal geometry. II. Comparative behaviour
Prior, C.; Yeates, A.
Authors
A. Yeates
Abstract
Aims. Sigmoidal structures in the solar corona are commonly associated with magnetic flux ropes whose magnetic field lines are twisted about a mutual axis. Their dynamical evolution is well studied, with sufficient twisting leading to large-scale rotation (writhing) and vertical expansion, possibly leading to ejection. Here, we investigate the behaviour of flux ropes whose field lines have more complex entangled/braided configurations. Our hypothesis is that this internal structure will inhibit the large-scale morphological changes. Additionally, we investigate the influence of the background field within which the rope is embedded. Methods. A technique for generating tubular magnetic fields with arbitrary axial geometry and internal structure, introduced in part I of this study, provides the initial conditions for resistive-MHD simulations. The tubular fields are embedded in a linear force-free background, and we consider various internal structures for the tubular field, including both twisted and braided. These embedded flux ropes are then evolved using a 3D MHD code. Results. Firstly, in a background where twisted flux ropes evolve through the expected non-linear writhing and vertical expansion, we find that flux ropes with sufficiently braided/entangled interiors show no such large-scale changes. Secondly, embedding a twisted flux rope in a background field with a sigmoidal inversion line leads to eventual reversal of the large-scale rotation. Thirdly, in some cases a braided flux rope splits due to reconnection into two twisted flux ropes of opposing chirality – a phenomenon previously observed in cylindrical configurations. Conclusions. Sufficiently complex entanglement of the magnetic field lines within a flux rope can suppress large-scale morphological changes of its axis, with magnetic energy reduced instead through reconnection and expansion. The structure of the background magnetic field can significantly affect the changing morphology of a flux rope.
Citation
Prior, C., & Yeates, A. (2016). Twisted versus braided magnetic flux ropes in coronal geometry. II. Comparative behaviour. Astronomy & Astrophysics, 591, Article A16. https://doi.org/10.1051/0004-6361/201528053
Journal Article Type | Article |
---|---|
Acceptance Date | Mar 2, 2016 |
Online Publication Date | Jun 3, 2016 |
Publication Date | Jul 1, 2016 |
Deposit Date | Mar 10, 2016 |
Publicly Available Date | Mar 15, 2016 |
Journal | Astronomy and astrophysics. |
Print ISSN | 0004-6361 |
Electronic ISSN | 1432-0746 |
Publisher | EDP Sciences |
Peer Reviewed | Peer Reviewed |
Volume | 591 |
Article Number | A16 |
DOI | https://doi.org/10.1051/0004-6361/201528053 |
Files
Accepted Journal Article
(25.2 Mb)
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Copyright Statement
Reproduced with permission from Astronomy & Astrophysics, © ESO
Published Journal Article
(61.5 Mb)
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