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Title: Nonlinear Force-free Coronal Magnetic Stereoscopy

Abstract

Insights into the 3D structure of the solar coronal magnetic field have been obtained in the past by two completely different approaches. The first approach are nonlinear force-free field (NLFFF) extrapolations, which use photospheric vector magnetograms as boundary condition. The second approach uses stereoscopy of coronal magnetic loops observed in EUV coronal images from different vantage points. Both approaches have their strengths and weaknesses. Extrapolation methods are sensitive to noise and inconsistencies in the boundary data, and the accuracy of stereoscopy is affected by the ability of identifying the same structure in different images and by the separation angle between the view directions. As a consequence, for the same observational data, the 3D coronal magnetic fields computed with the two methods do not necessarily coincide. In an earlier work (Paper I) we extended our NLFFF optimization code by including stereoscopic constrains. The method was successfully tested with synthetic data, and within this work, we apply the newly developed code to a combined data set from SDO /HMI, SDO /AIA, and the two STEREO spacecraft. The extended method (called S-NLFFF) contains an additional term that monitors and minimizes the angle between the local magnetic field direction and the orientation of themore » 3D coronal loops reconstructed by stereoscopy. We find that when we prescribe the shape of the 3D stereoscopically reconstructed loops, the S-NLFFF method leads to a much better agreement between the modeled field and the stereoscopically reconstructed loops. We also find an appreciable decrease by a factor of two in the angle between the current and the magnetic field. This indicates the improved quality of the force-free solution obtained by S-NLFFF.« less

Authors:
; ;  [1]
  1. Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)
Publication Date:
OSTI Identifier:
22661342
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 837; 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; BOUNDARY CONDITIONS; EXTRAPOLATION; MAGNETIC FIELDS; NOISE; NONLINEAR PROBLEMS; OPTIMIZATION; SOLAR CORONA; SPACE VEHICLES; STELLAR CORONAE; SUN

Citation Formats

Chifu, Iulia, Wiegelmann, Thomas, and Inhester, Bernd, E-mail: chifu@mps.mpg.de. Nonlinear Force-free Coronal Magnetic Stereoscopy. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA5B9A.
Chifu, Iulia, Wiegelmann, Thomas, & Inhester, Bernd, E-mail: chifu@mps.mpg.de. Nonlinear Force-free Coronal Magnetic Stereoscopy. United States. doi:10.3847/1538-4357/AA5B9A.
Chifu, Iulia, Wiegelmann, Thomas, and Inhester, Bernd, E-mail: chifu@mps.mpg.de. Wed . "Nonlinear Force-free Coronal Magnetic Stereoscopy". United States. doi:10.3847/1538-4357/AA5B9A.
@article{osti_22661342,
title = {Nonlinear Force-free Coronal Magnetic Stereoscopy},
author = {Chifu, Iulia and Wiegelmann, Thomas and Inhester, Bernd, E-mail: chifu@mps.mpg.de},
abstractNote = {Insights into the 3D structure of the solar coronal magnetic field have been obtained in the past by two completely different approaches. The first approach are nonlinear force-free field (NLFFF) extrapolations, which use photospheric vector magnetograms as boundary condition. The second approach uses stereoscopy of coronal magnetic loops observed in EUV coronal images from different vantage points. Both approaches have their strengths and weaknesses. Extrapolation methods are sensitive to noise and inconsistencies in the boundary data, and the accuracy of stereoscopy is affected by the ability of identifying the same structure in different images and by the separation angle between the view directions. As a consequence, for the same observational data, the 3D coronal magnetic fields computed with the two methods do not necessarily coincide. In an earlier work (Paper I) we extended our NLFFF optimization code by including stereoscopic constrains. The method was successfully tested with synthetic data, and within this work, we apply the newly developed code to a combined data set from SDO /HMI, SDO /AIA, and the two STEREO spacecraft. The extended method (called S-NLFFF) contains an additional term that monitors and minimizes the angle between the local magnetic field direction and the orientation of the 3D coronal loops reconstructed by stereoscopy. We find that when we prescribe the shape of the 3D stereoscopically reconstructed loops, the S-NLFFF method leads to a much better agreement between the modeled field and the stereoscopically reconstructed loops. We also find an appreciable decrease by a factor of two in the angle between the current and the magnetic field. This indicates the improved quality of the force-free solution obtained by S-NLFFF.},
doi = {10.3847/1538-4357/AA5B9A},
journal = {Astrophysical Journal},
number = 1,
volume = 837,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2017},
month = {Wed Mar 01 00:00:00 EST 2017}
}