Nlte Modeling Of A Small Active Region Filament Observed With The Vtt

An active region mini-filament was observed with the Vacuum Tower Telescope (VTT) in Tenerife simultaneously in the He i infrared triplet using the Tenerife Infrared Polarimeter 1 (TIP 1), in H alpha with the TESOS Fabry-Perot interferometer, and in Ca ii 8542 with the VTT spectrograph. The spectropolarimetric data were inverted using the HAZEL code and Ha profiles were modelled by solving a NLTE radiative transfer in a simple isobaric and isothermal 2D slab irradiated both from its bottom and sides from the solar surface. It was found that the mini-filament is composed of horizontal fluxtubes, along which the cool plasma of T similar to 10 000K can flow with very large, even supersonic, velocities. (C) 2016 WILEY-VCH Verlag GmbH& Co. KGaA, Weinheim