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

Journal Article · Wed Jan 01 04:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/780/1/101· OSTI ID:22348275

Inoue, S.; Magara, T.; Choe, G. S.; Kim, K. S. ^[1]; Pandey, V. S. ^[2]; Shiota, D.

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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)

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.

• OSTI ID: 22348275
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 780; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCURACY
ALGORITHMS
CAPTURE
COMPUTERIZED SIMULATION
ERRORS
EXPANSION
EXTRAPOLATION
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
PHOTOSPHERE
RELAXATION
RESOLUTION
SUN
TOPOLOGY