Solar Magnetic Fields and Convection: VII.A Review of the Primordial Field Theory

Abstract

We review the primordial field theory of solar magnetic fields (Papers I–VI) whose three main features are, first, a permanent dipole-like magnetic field, second a mainly toroidal field formed by shearing and rolling into individual, helically twisted ropes as suggested by Babcock, and third a mechanism for reversing the toroidal field. The theory explains numerous observational effects where the dynamo theory fails.(i) An active region forms when a rope section emerges and expands layer by layer to form a rotating arch filament system and then spots. Only a rope model explains the radial inflow of magnetic elements to build up a spot, as well as the spiral structure and other features pointed out by Babcock. (ii) The model explains umbral and penumbral structures, the Wilson depression, Evershed flow, the sunspot energy deficit and the very slow loss of flux fragments by some sunspots. (iii) The model is then extended to background magnetic fields to show that surface magnetic fields are like the upppermost branches of a magnetic ‘tree’ whose trunk is a flux rope. This explains unipolar magnetic regions, ‘pepper and salt’, and ephemeral active regions. Tension in the submerged flux ropes accounts for the observed migrations of magnetic regions, active longitudes and magnetic longitudes. (iv) On a smaller scale spicules, mottles and other network elements are explained in terms of the tree structure. (v) The mechanism of reversal of the toroidal field system is explained and the manner of disposal of old toroidal fields. (vi) The basic error in the dynamo theory is discussed briefly. We point out that radical changes in dynamo theory have been suggested by Parker, but appear to have been ignored by others.