Observational Study of the Three-Dimensional Magnetic Field Structure and Mass Motion in Active Regions

Abstract

Spectro-polarimetric observations of active regions were carried out in the spectral lines of Si i 10827.1 Å  and He i 10830 Å  to study the three-dimensional magnetic field structure and associated plasma flow properties. Comparison of Si i and He i magnetograms with the potential field model shows that a large fraction of the magnetic field is consistent with the potential field structure, by assuming that the height difference between the origin of the two lines is about 1200 km. The slope of the scatter plot between Si i and He i magnetograms is 0.5, 0.76 in an emerging flux and a larger active region, respectively. These values are lower than the scatter plot slopes obtained from Kitt Peak photospheric and chromospheric magnetograms, in which case the corresponding values are 0.83 and 0.9, respectively. Considering the height difference between these two sets of chromospheric magnetograms, this implies that the magnetic field spreads out faster near the transition region heights. Dopplergrams obtained by determining the centroid of the asymmetric line profiles show that, in case of emerging flux region, the chromospheric upflow regions are located in the magnetic neutral line areas.