Solar dynamo surface waves in the presence of a primordial magnetic field: A 30 gauss upper limit in the solar core

Helioseismological measurements have recently shown that the vertical gradient in angular velocity is confined to a thin layer in the overshoot region just below the convective zone of the Sun. A solar dynamo operating in this configuration exhibits surface (or interface) wave properties and is confined primarily to just below the convective/shear boundary. A fixed primordial magnetic field bound to the radiative core is observed to be modified at the solar surface by the dynamo and is found to be a sensitive function of the shear layer thickness h. If the solar dynamo operates as an alpha-omega surface dynamo, then, based on current observations of solar cycle asymmetry and allowing for the present uncertainty in the value for h, an upper bound of 0.15-0.5 G for the primordial magnetic field magnitude at the bottom of the convective zone is calculated. By comparing the age of the Sun with the solar decay time for a magnetic field initially trapped in the solar core, we estimate the magnetic field in the interior of the Sun's core to have an upper magnitude of around 30 G. Because of this low value, solutions to the solar neutrino problem based on high magnetic fields in the core thus become untenable.