Winding Up The Field

Winding Up The Field

. A model for generating the orientation and polarity of the sunspot magnetic fields. At the beginning of the 11-year cycle of magnetic activity, when the number of sunspots is at a minimum, the magnetic field is the dipolar (poloidal) field seen at the poles of the Sun (a). The internal magnetic fields then runs just below the photosphere from the south to north poles. As time goes on, the highly-conductive, rotating material inside the Sun carries the magnetic field along and winds it up. Because the equatorial regions rotate at a faster rate than the polar ones, the internal magnetic fields become stretched out and wrapped round the Sunís center, becoming deformed into a partly toroidal field (b) and (c). At the time of activity maximum (c), active regions are formed in two belts, in the northern and southern hemispheres, and bipolar sunspot groups are created when magnetic loops break through the photosphere.

Copyright 2010, Professor Kenneth R. Lang, Tufts University