Chirality of Intermediate Filaments and Magnetic Helicity of Active Regions

TL;DR

This study reveals a strong correlation between the chirality of intermediate solar filaments and the magnetic helicity of their associated active regions, challenging previous theoretical predictions about the role of PIL orientation.

Contribution

It demonstrates that the chirality of intermediate filaments is primarily linked to the magnetic helicity of active regions, providing new insights into filament formation and magnetic field topology.

Findings

42 out of 45 filaments share the same helicity sign as their ARs

The orientation and PIL direction are not significant in determining filament chirality

Chirality likely originates from magnetic helicity of ARs

Abstract

Filaments which form either between or around active regions (ARs) are called intermediate filaments. In spite of various theoretical studies, the origin of the chirality of filaments is still uncovered. We investigated how intermediate filaments are related to their associated ARs, especially from the point of view of magnetic helicity and the orientation of polarity inversion lines (PILs). The chirality of filaments has been determined based on the orientations of barbs observed in BBSO full-disk Halpha images taken during the rising phase of solar cycle 23. The sign of magnetic helicity of ARs has been determined using S/inverse-S shaped sigmoids from Yohkoh SXT images. As a result, we have found a good correlation between the chirality of filaments and the magnetic helicity sign of ARs. Among 45 filaments, 42 filaments have shown the same sign as helicity sign of nearby ARs. It has been also confirmed that the role of both the orientation and the relative direction of PILs to ARs in determining the chirality of filaments is not significant, against a theoretical prediction. These results suggest that the chirality of intermediate filaments may originate from magnetic helicity of their associated ARs.