A POTENTIAL-FIELD MODEL FOR DEXTRAL AND SINISTRAL FILAMENT CHANNELS

Recent observations of Martin, Bilimoria, and Tracadas (1995) have rev ealed two new magnetic and structural classes for solar filaments and filament channels. The magnetic classes are called sinistral and dextr al, while the structural classes are left-bearing and right-bearing. D extral filaments dominate in the northern hemisphere and sinistral in the southern. A model consistent with the observations is developed wi th magnetic sources that represent the network flux on both sides of t he channel and extra concentrations of flux that produce the strong fi eld component along the channel. We suggest that it is the imbalance o f Aux locations along the channel that creates the field of a filament channel. The resulting separatrix surfaces have distinct upper and lo wer boundaries that may produce the upper boundary of the filament cav ity or filament and the lower boundary of the filament. The model is a pplied to a specific filament channel, with discrete sources and sinks that represent the flux observed in a photospheric magnetogram The re sulting three-dimensional field lines near the filament location are l ow-lying and possess dips.