An MHD avalanche in a multi-threaded coronal loop

Alan William Hood, Peter Cargill, Philippa Browning, Kuan Tam

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)
2 Downloads (Pure)

Abstract

For the first time, we demonstrate how an MHD avalanche might occur in a multithreaded coronal loop. Considering 23 non-potential magnetic threads within a loop, we use 3D MHD simulations to show that only one thread needs to be unstable in order to start an avalanche even when the others are below marginal stability. This has significant implications for coronal heating in that it provides for energy dissipation with a trigger mechanism. The instability of the unstable thread follows the evolution determined in many earlier investigations. However, once one stable thread is disrupted, it coalesces with a neighboring
thread and this process disrupts other nearby threads. Coalescence with these disrupted threads then occurs leading to the disruption of yet more threads as the avalanche develops. Magnetic energy is released in discrete bursts as the surrounding stable threads are disrupted. The volume integrated heating, as a function of time, shows short spikes suggesting that the temporal form of the heating is more like that of nanoflares than of constant heating.
Original languageEnglish
Article number5
Pages (from-to)1-7
Number of pages7
JournalAstrophysical Journal
Volume817
Issue number1
Early online date18 Jan 2016
DOIs
Publication statusPublished - 20 Jan 2016

Keywords

  • Magnetohydrodynamics (MHD)
  • Methods: numerical
  • Sun: activity
  • Sun: corona
  • Sun: magnetic fields

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