Force-Free Magneto-Stereoscopy of Coronal Loops
Abstract
We derive an analytical approximation of nonlinear force-free magnetic field solutions (NLFFF) that can efficiently be used for fast forward-fitting to solar magnetic data, constrained either by observed line-of-sight magnetograms and stereoscopically triangulated coronal loops, or by 3D vector-magnetograph data. We test the code by forward-fitting to simulated data, to force-free solutions derived by Low and Lou (1990), and to active regions observed with STEREO/EUVI and SOHO/MDI. The forward-fitting tests demonstrate: (i) a satisfactory convergence behavior (with typical misalignment angles of 1-10 deg), (ii) a high fidelity of retrieved force-free alpha-parameters, and (iii) relatively fast computation times (from seconds to minutes). The novel feature of this NLFFF code is the derivation of a quasi-forcefree field based on coronal constraints, which bypasses the non-forcefree photosphere of standard magnetograms. Applications range from magnetic modeling of loops to the determnination of electric currents, twist, helicity, and free (non-potential) energy in active regions.
- Publication:
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American Astronomical Society Meeting Abstracts #220
- Pub Date:
- May 2012
- Bibcode:
- 2012AAS...22041103A