Continuous upflow of material in an active region filament from the photosphere to the corona

TL;DR

This study uses spectropolarimetric data to analyze the magnetic and velocity structures of an active region filament, revealing evidence of an emerging flux rope from the photosphere to the corona.

Contribution

It provides the first detailed comparison of photospheric and chromospheric magnetic fields in an active region filament using spectropolarimetric inversions.

Findings

Magnetic fields are well aligned in some filament areas.

Upflows of field lines are observed at both heights.

Evidence supports an emerging flux rope scenario.

Abstract

Using spectropolarimetric data of an Active Region (AR) filament we have carried out inversions in order to infer vector magnetic fields in the photosphere (Si I line) and in the chromosphere (He I line). Our filament lies above the polarity inversion line (PIL) situated close to disk center and presents strong Zeeman-like signatures in both photospheric and chromospheric lines. Pore-like formations with both polarities are identified in the continuum under the PIL. The azimuth ambiguity is solved at both heights using the AZAM code. A comparison between the photospheric and chromospheric vector magnetic fields revealed that they are well aligned in some areas of the filament. However, especially at chromospheric heights, the magnetic field is mostly aligned with the dark threads of the filament. Velocity signatures indicating upflows of field lines are found at both heights. The combination of all these findings strongly suggests an emerging flux rope scenario.