Fig 1.1. Active-region dextral filament (S. Martin).
(a) Dextral-Sinistral Model
Sara Martin has made an important discovery about the global nature of prominences, namely that most of them are dextral in the northern hemisphere (with right-ward branching barbs when viewed from above and a right-directed axial magnetic field when viewed from the positive polarity side) and sinistral in the southern hemisphere (with a corresponding left-orientated character). We have therefore developed with invaluable suggestions from Sara Martin and other members of the PROM team a model (Priest, van Ballegooijen and MacKay, 1996, Astrophys. J. 460, 530) to explain these properties.
Fig 1.2. Model of chiral structure.
Fig 1.3. Alternative scenario.
(b) Model for Global and Fibril Structure
More recently, we have developed the above ideas further to give a Dynamic Dextral-Sinistral model for the structure and evolution of prominences (Priest, 1997, Proc IAU Colloq 167, ed. D Webb et al, in press) suggesting the following:
Fig 1.4. Formation and dissolution of a fibril.
Fig 1.5. Global field and barbs of a prominence.
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