Solar Activity

SOLIS: A Modern Facility for Synoptic Solar Observations

Resolution of magnetic flux tubes on the Sun

Magnetic flux at the surface of the Sun is predominantly concentrated in discrete areas with kilogauss field strengths. Except for sunspots, these areas are too small to have been resolved by conventional observations. These magnetic flux tubes are …

Solar speckle polarimetry

The combination of a polarimeter with real-time frame selection and differential speckle imaging results in diffraction-limited magnetograms that provide new insight into the morphology of solar small-scale magnetic fields. The method to record …

Multicolor Continuum Analysis of the Solar Granulation in Quiet and Active Regions

A set of narrow-band filtergrams of the solar photosphere recorded in three widely separated true continuum windows and in Mg I b1 with a spatial resolution of about 0.5 arcsec is analyzed. The influence of small-scale magnetic fields on the …

Dependence of the properties of solar magnetic flux tubes on filling factor. II - Results of an inversion approach

The dependence of the properties of solar magnetic elements on the magnetic filling factor is studied using Stokes V spectra of three lines observed near the center of the solar disk. The inversion technique developed by Keller et al. (1990) is …

Solar magnetic field strength determinations from high spatial resolution filtergrams

Circularly polarized images with high spatial resolution (better than 1 arcsec) of a solar active region, obtained with a tunable filter in the wings of Fe I 5247.1 A and Fe I 5250.2 A, have been analyzed in terms of the magnetic line ratio technique …