Mackay, Duncan Hendry

Contact Email: duncan@mcs.st-and.ac.uk
Institute: Mathematics Department, University of St.
Andrews North Haugh, St. Andrews, Fife, Scotland, KY16 9SS
First Coauthor: A. A. van Ballegooijen
Institute: Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
Research URL:http://www-solar.mcs.st-and.ac.uk/~duncan
Subject Area: The Sun
Waveband: Optical
Technique: Computational Astrophysics
Presentation: Poster Display
Title: A Possible Solar Cycle Dependance to the Hemispheric Pattern of Filament Magnetic Fields?
Abstract: The origin of the observed hemispheric pattern of filament magnetic fields is considered. Using a magnetic flux transport model, we simulate the interactions of magnetic bipoles with each other and with polar magnetic fields in the rising and declining phases of the solar activity cycle. In contrast with previous studies, the non-potential character of the initial coronal fields is taken into account, and the dependence of the hemispheric pattern on the initial tilt and helicity of the bipoles is considered. For the rising phase of the cycle a range of initial bipole twists and tilt angles can be found which reproduce the observed hemispheric pattern. However, for the declining phase no such range can be found: the predicted fields on the return arms at the rear of switchbacks are consistent with filament observations, but those on the high latitude east-west arms are not. It is argued that existing observations of the hemispheric pattern are weighted towards the rising phase of the solar activity cycle and may give us a biased view of the sun. New observations of filament magnetic fields are needed to determine whether there is a cycle dependence of the observed hemispheric pattern.