HIGH-SPATIAL-RESOLUTION SPECTRO-POLARIMETRY OF SMALL-SCALE MAGNETIC ELEMENTS ON THE SUN

Spectro-polarimetric observations from plage regions on the Sun, obtained with the Gregory Coude Telescope at Observatorio del Teide/Tenerife, were analysed. They consist of high spatial resolution data recorded with a Stokes V polarimeter and a CCD detector from the magnetically sensitive lines Fe II 6149 (g(eff) = 1.33) and Fe I 6151 (g(eff) = 1.83) simultaneously with the non-magnetic Fe I 5576 line and from Fe I 6173 (g(eff) = 2.5) also simultaneously with Fe I 5576. The average asymmetries of the V profiles are in agreement with previous measurements obtained with low spatial resolution, and the average wavelength positions of the zero crossings of the V profiles are consistent with the picture of zero average velocity within magnetic fluxtubes. Within the magnetic features and from one feature to the next, there exist strong fluctuations of the asymmetries of the emergent V profiles and of the velocities. The latter can be as large as 1 km s-1. Yet neither a correlation nor an anticorrelation between asymmetry and flow can be found. Siphon flows may occur across the borders of regions with opposite polarity. On some locations with high V signal we see very strong line weakenings and suggest that there the area filling factor of the magnetic elements amounts to 30 - 50 %. At a height of about 200 km the tubes merge and loose their identity. The magnetic field strengths can be derived from the separation of the extrema of the V profiles of Fe I 6173. They are large, about 2500 gauss (at tau5 = 1 in the tube). The V profiles observed with high spatial resolution do not seem to require high non-thermal, micro- or macroturbulent broadening.