||Spectropolarimetric Observations of an Arch Filament System with GREGOR
||526, Solar Polarization Workshop 8
||Balthasar, H.; Gömöry, P.; González Manrique, S. J.; Kuckein, C.; Kučera, A.; Schwartz, P.; Berkefeld, T.; Collados, M.; Denker, C.; Feller, A.; Hofmann, A.; Schmidt, D.; Schmidt, W.; Sobotka, M.; Solanki, S. K.; Soltau, D.; Staude, J.; Strassmeier, K. G.; von der Lühe, O.
||We observed an arch filament system (AFS) in a sunspot group with the
GREGOR Infrared Spectrograph attached to the GREGOR solar telescope.
The AFS was located between the leading sunspot of negative polarity
and several pores of positive polarity forming the following part of the
We recorded five spectro-polarimetric scans of this region. The spectral
range included the spectral lines Si I 1082.7 nm, He I
1083.0 nm, and Ca I 1083.9 nm.
In this work we concentrate on the silicon line which is
formed in the upper photosphere. The line profiles are inverted
with the code ‘Stokes Inversion based on Response functions' to obtain
the magnetic field vector. The line-of-sight velocities are determined
independently with a Fourier phase method. Maximum velocities are found
close to the ends of AFS fibrils.
These maximum values amount to 2.4 km s-1 next to the pores and to
4 km s-1 at the sunspot side.
Between the following pores, we encounter an area of negative polarity
that is decreasing during the five scans. We interpret this by new
emerging positive flux in this area canceling out the negative flux.
In summary, our findings confirm the scenario that rising magnetic flux
tubes cause the AFS.