CHIRALITY AND MAGNETIC CONFIGURATIONS OF SOLAR FILAMENTS

It has been revealed that the magnetic topology in the solar atmosphere displays hemispheric preference, i.e., helicity is mainly negative/positive in the northern/southern hemispheres, respectively. However, the strength of the hemispheric rule and its cyclic variation are controversial. In this paper, we apply a new method based on the filament drainage to 571 erupting filaments from 2010 May to 2015 December in order to determine the filament chirality and its hemispheric preference. It is found that 91.6% of our sample of erupting filaments follows the hemispheric rule of helicity sign. It is also found that the strength of the hemispheric preference of the quiescent filaments decreases slightly from similar to 97% in the rising phase to similar to 85% in the declining phase of solar cycle 24, whereas the strength of the intermediate filaments keeps a high value around 96 +/- 4% at all times. Only the active-region filaments show significant variations. Their strength of the hemispheric rule rises from similar to 63% to similar to 95% in the rising phase, and keeps a high value of 82% +/- 5% during the declining phase. Furthermore, during a half-year period around the solar maximum, their hemispheric preference totally vanishes. Additionally, we also diagnose the magnetic configurations of the filaments based on our indirect method and find that in our sample of erupting events, 89% are inverse-polarity filaments with a flux rope magnetic configuration, whereas 11% are normal-polarity filaments with a sheared arcade configuration.