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Title: Nonlinear force-free extrapolation of the coronal magnetic field based on the magnetohydrodynamic relaxation method

We develop a nonlinear force-free field (NLFFF) extrapolation code based on the magnetohydrodynamic (MHD) relaxation method. We extend the classical MHD relaxation method in two important ways. First, we introduce an algorithm initially proposed by Dedner et al. to effectively clean the numerical errors associated with ∇ · B . Second, the multigrid type method is implemented in our NLFFF to perform direct analysis of the high-resolution magnetogram data. As a result of these two implementations, we successfully extrapolated the high resolution force-free field introduced by Low and Lou with better accuracy in a drastically shorter time. We also applied our extrapolation method to the MHD solution obtained from the flux-emergence simulation by Magara. We found that NLFFF extrapolation may be less effective for reproducing areas higher than a half-domain, where some magnetic loops are found in a state of continuous upward expansion. However, an inverse S-shaped structure consisting of the sheared and twisted loops formed in the lower region can be captured well through our NLFFF extrapolation method. We further discuss how well these sheared and twisted fields are reconstructed by estimating the magnetic topology and twist quantitatively.
Authors:
; ; ;  [1] ;  [2] ; ;  [3]
  1. School of Space Research, Kyung Hee University, Yongin, Gyeonggi-do 446-701 (Korea, Republic of)
  2. Department of Physics, National Institute of Technology, Dwarka, Sector-9, Delhi-110077 (India)
  3. Solar-Terrestrial Environment Laboratory, Furo-Cho, Chikusa-ku Nagoya 464-8601 (Japan)
Publication Date:
OSTI Identifier:
22348275
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 780; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; ALGORITHMS; CAPTURE; COMPUTERIZED SIMULATION; ERRORS; EXPANSION; EXTRAPOLATION; MAGNETIC FIELDS; MAGNETOHYDRODYNAMICS; PHOTOSPHERE; RELAXATION; RESOLUTION; SUN; TOPOLOGY