SPATIAL VARIATION OF THE MAGNETIC-FIELD INCLINATION IN A SUNSPOT PENUMBRA

Stokes-V spectra from a sunspot penumbra at curly-theta = 11.5-degrees show significant spatial fluctuations. Due to its deep formation layer, the Fe 6842.7 used is totally split (B = 2200 Gs) showing field fluctuations of the order of 10%. The spatial variations of the Stokes-V spectra (Fig.1) are strongly affected by telescopic phase retardation thus allowing only a rough estimate of the inclination angle. Its fluctuation by 7-degrees < DELTA-psi < 13.5-degrees to the solar surface is spatially related to the field strength fluctuation in the sense that steeper fields are stronger. Doppler shifts of the Stokes-V give a slight indication for upward motions at locations of steeper field inclination. A relation with the continuum intensity fluctuation is only found in the centre-side penumbra - possibly due to the steeper angle-of-view. The absence of a similar correlation in the limb-side spectra agrees with earlier findings that field strength and Evershed effect are not related to penumbral fine-structures.