Regensburg 2007 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 8: Sonne

EP 8.2: Talk

Wednesday, March 28, 2007, 14:15–14:30, H46

Reconstruction of coronal magnetic fields with the magneto-frictional method — •gherardo valori, bernhard kliem, and axel hofmann — Astrophysikalisches Institut Potsdam, Potsdam, Germany

Coronal mass ejections and solar flares are powered by the magetic energy contained in the coronal field, and their triggering mechanisms are intimately related to the field structure. On the other hand, measurements of vector fields are available only at low altitudes in the solar atmosphere. The numerical extrapolation of photospheric boundary data (vector magnetograms) into the corona is then the only available technique that can provide the missing information about the coronal magnetic field.

We present here extrapolations of a class of solar-relevant, test magnetic equilibria containing a flux rope. We show that the magneto-frictional method can reconstruct force-free magnetic fields with an exceptionally high degree of accuracy, despite the fact that information about the nonlinear field is limited to one boundary only. Additionally, the extrapolation of measured magnetograms is now possible, which allows for comparing eruption models with real measurements. However, the complex magnetic field topology, as well as errors and inconsistency in the magnetograms, make the extrapolation task more challenging. As an example, we present here a successful extrapolation of a measured magnetogram. The obtained magnetic field structure is discussed, together with the influence of small scales and magnetogram inconsistencies on the reconstructed field.