Spatial offsets between lines and continuum in limb faculae

摘要

High-spatial-resolution spectra of limb faculae show spatial displacements of line cores relative to the adjacent continuum at cos θ<0.35, confirming results from earlier photographic analyses. The observed displacements are geometric measures which probe the upper atmospheric layers of fluxtubes forming facular grains. We selected spectra with highest contrast and smallest width of the facular continuum streaks, in order to avoid clustered structures. The spatial displacements of Stokes-Q and -V maxima were also measured: we find Q-signals spatially located near the continuum, as is expected from their origin in line wings; V-signals – which should give evidence for the existence of horizontal fields – are not found, except for one case of a 'hidden' pore.