On the Relationship Between Current and Magnetic Field in Ring-Filaments

Abstract

There is a type of filament that forms closed contours encircling regions of one polarity of magnetic field, while the surrounding region has the opposite polarity. One distribution of ring-filaments has sizes 2R = 40,000 to 160,000 km with the maximum around 100,000 km; the other distribution (with filaments and filament channels) has bigger sizes, with a maximum around 300,000 km. At low and mid latitudes the radial component B_rs (radial for the Sun) in the region outlined by filaments varies from 50 to 100 gauss, while the longitudinal component B_ϕ , varies from 10 to 30 gauss. The total current inside the filament is 10¹⁰ – 10¹¹ A, the ratio R/a ≈ 5 to 10, the magnetic flux crossing the surface is ≈ 10²¹ – 10²²Mx; the magnetic energy is ≈ 10²⁹ – 10³¹erg. Polar ring-filaments at latitudes 60° – 80° are related to the polar magnetic field reversal and the quasi-flare processes at the poles during the field reversal. Correlation between B_rs and B_ϕ , for the polar filament bands cannot be satisfactorily explained. A theoretical model using the conservation laws is used to study the relations between the various fields, currents, etc. of shrinking polar ring-filaments and their evolution. According to this theory ring-filaments should rise higher above the photosphere when shrinking. However, observations show that the height lowers. Presumably the discrepancy is due to the lack of dissipation in the model.