Reconstructing solar magnetic fields from historical observations

Helical Magnetic Fields in Solar Active Regions: Theory vs. Observations

The mean value of the normalized current helicity αp = B · (∇×B)/B 2 in solar active regions is on the order of 10 m, negative in the northern hemisphere, positive in the southern hemisphere. Observations indicate that this helicity has a subsurface origin. Possible mechanisms leading to a twist of this amplitude in magnetic flux tubes include the solar dynamo, convective buffeting of rising fl...

Solar Magnetic Fields

Consistent determination of quasi force-free magnetic fields from observations in solar active regions

The classical concept of extrapolating the photospheric magnetic field from line-of-sight measurements B` assuming a pure force-free field is revisited and a new procedure is proposed which is based on: 1) non-vanishing magnetic forces, 2) known horizontal forces from direct measurement of pressure or a related quantity (continuum brightness), 3) a small perturbation to the potential or linear ...

Observations of Solar Coronal Magnetic

This review discusses methods for determining solar coro-nal magnetic elds, with an emphasis on radio measurements of eld strengths in solar active regions.

The Magnetic Field of the Solar Corona from Pulsar Observations

Abstract. We present a novel experiment with the capacity to independently measure both the electron density and the magnetic field of the solar corona. We achieve this through measurement of the excess Faraday rotation due to propagation of the polarised emission from a number of pulsars through the magnetic field of the solar corona. This method yields independent measures of the integrated e...