An optimization principle for the computation of MHD equilibria in the solar corona
Abstract
Aims.We develop an optimization principle for computing stationary MHD equilibria.
Methods: . Our code for the self-consistent computation of the coronal magnetic fields and the coronal plasma uses non-force-free MHD equilibria. Previous versions of the code have been used to compute non-linear force-free coronal magnetic fields from photospheric measurements. The program uses photospheric vector magnetograms and coronal EUV images as input. We tested our reconstruction code with the help of a semi-analytic MHD-equilibrium. The quality of the reconstruction was judged by comparing the exact and reconstructed solution qualitatively by magnetic field-line plots and EUV-images and quantitatively by several different numerical criteria.
Results: . Our code is able to reconstruct the semi-analytic test equilibrium with high accuracy. The stationary MHD optimization code developed here has about the same accuracy as its predecessor, a non-linear force-free optimization code. The computing time for MHD-equilibria is, however, longer than for force-free magnetic fields. We also extended a well-known class of nonlinear force-free equilibria to the non-force-free regime for purposes of testing the code.
Conclusions: . We demonstrate that the code works in principle using tests with analytical equilibria, but it still needs to be applied to real data.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 2006
- DOI:
- 10.1051/0004-6361:20065281
- arXiv:
- arXiv:astro-ph/0612625
- Bibcode:
- 2006A&A...457.1053W
- Keywords:
-
- Sun: magnetic fields;
- Sun: corona;
- Sun: photosphere;
- magnetohydrodynamics (MHD);
- Astrophysics;
- Physics - Computational Physics
- E-Print:
- 6 pages, 3 figures