http://arxiv.org/abs/1812.02489
Filament is a cool, dense structure suspended in the solar corona. The eruption of a filament is often associated with coronal mass ejection (CME), which has an adverse effect on space weather. Hence, the study of filament has attracted much attention in the recent past. The tilt angle of active region (AR) magnetic bipoles is a crucial parameter in the context of the solar dynamo. It governs the conversion efficiency of the toroidal magnetic field to poloidal magnetic field. The filament always forms over the Polarity Inversion Lines (PILs). So the study of tilt angles of the filament can provide valuable information about generation of magnetic field in the Sun. We study the tilt angle of filaments and other properties of it using McIntosh archive data. We fit a straight line to each filament to estimate its tilt angle. We study the variation of mean tilt angle with time. The latitude distribution of positive tilt angle filaments and negative tilt angle filaments reveal that there is a dominance of positive tilt angle filaments in the southern hemisphere and negative tilt angle filaments dominate in the northern hemisphere. We study the variation of the mean tilt angle for low and high latitude separately. Study of temporal variation of filament number reveals that total filament number and low latitude filament number varies cyclically, in phase with the solar cycle. The number of filaments in high latitude is less, and they also show a cyclic pattern in temporal variation. We also study the north-south asymmetry of filament for different latitude criteria.
R. Mazumder
Fri, 7 Dec 18
63/66
Comments: 12 pages, 10 figures, accepted for publication in RAA
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