Magnetohydrodynamic evolution of magnetic skeletons

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47 Citations (Scopus)

Abstract

The heating of the solar corona is probably due to reconnection of the highly complex magnetic field that threads throughout its volume. We have run a numerical experiment of an elementary interaction between the magnetic field of two photospheric sources in an overlying field that represents a fundamental building block of the coronal heating process. The key to explaining where, how and how much energy is released during such an interaction is to calculate the resulting evolution of the magnetic skeleton. A skeleton is essentially the web of magnetic flux surfaces (called separatrix surfaces) that separate the coronal volume into topologically distinct parts. For the first time, the skeleton of the magnetic field in a three-dimensional numerical magnetohydrodynamic experiment is calculated and carefully analysed, as are the ways in which it bifurcates into different topologies. A change in topology normally changes the number of magnetic reconnection sites.

In our experiment, the magnetic field evolves through a total of six distinct topologies. Initially, no magnetic flux joins the two sources. Then, a new type of bifurcation, called a global double-separator bifurcation, takes place. This bifurcation is probably one of the main ways in which new separators are created in the corona (separators are field lines at which three-dimensional reconnection takes place). This is the first of five bifurcations in which the skeleton becomes progressively more complex before simplifying. Surprisingly, for such a simple initial state, at the peak of complexity there are five separators and eight flux domains present.

Original languageEnglish
Pages (from-to)1097-1115
Number of pages19
JournalProceedings of the Royal Society A - Mathematical, Physical & Engineering Sciences
Volume463
Issue number2080
DOIs
Publication statusPublished - 8 Apr 2007

Keywords

  • magnetohydrodynamics
  • Sun
  • magnetic fields
  • ELEMENTARY HEATING EVENTS
  • RAY BRIGHT POINTS
  • 2 FLUX SOURCES
  • CURRENT SHEETS
  • CORONAL SEISMOLOGY
  • ACTIVE REGIONS
  • NULL POINTS
  • FIELDS
  • RECONNECTION
  • MODEL

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