Combined loop stereoscopy and field extrapolations in active regions

The 3d magnetic corona   The solar magnetic field couples the solar interior with the photosphere and corona where it drives heating processes and eruptive phenomena. In the corona the magnetic energy is quasi-statically built up until it exceeds by far the energy stored in a potential magnetic configuration. This excess energy is intermittently released in parts by large eruptive phenomena, e.g. coronal mass ejections, flares and eruptive prominences, but also through small ones, such as explosive events and nano- and micro flares which are probably central for heating the solar corona. Knowledge regarding the coronal magnetic field therefore plays a key role for obtaining a better understanding of these phenomena. Most measurements of the magnetic field vector are restricted to the photosphere, so that the magnetic field needs to be extrapolated from there into the corona. High resolution vector magnetograms are available from ground based (SOLIS), balloon-born (Sunrise) and space born instruments (Hinode, SDO, in future Solar Orbiter). Codes for modelling the coronal magnetic field have been developed at the MPS and are continuously improved.

The solar magnetic field in a simulation.

A project in data analysis   In this project we want to apply a newly developed extension of the force-free field extrapolation code to observations. In this new extension, the extrapolation of surface magnetograms are supplemented with the 3D shape of individual loops to improve the field model. The loop shapes can be extracted from solar EUV images by means of stereoscopy reconstruction. The surface magnetograms are available from ground based (SOLIS) and space-born (SDO) vector magnetographs. The aim of the project is to derive the magnetic field of an active region which is consistent with both data sets.

View of part of a SOHO/MDI magnetogram, from DeRosa et al., Astrophysical Journal 696, 1780-1791 (2009).

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