Numerical Proof of the Possibility of Stably Generating Axisymmetric Magnetic Fields via Simple Convection

抄録

It is posited that the generation of celestial magnetic fields follows Cowling's theorem. However, in this study, we identify a phenomenon not accounted for in this theorem. For example, while Cowling's theorem addresses the magnetic field generation conditions at a given point on the poloidal surface, this theory suggests that phenomena at multiple points cooperate to generate a magnetic field. This paper highlights the shortcomings in Cowling's theorem. Because the magnetic field of celestial bodies is formed during the convection of an electrically conductive fluid, it is natural to assume that the magnetic field axis matches the convection or rotation axis. However, Cowling's theorem does not support this assumption, instead stating that an axisymmetric magnetic field along the same axis does not stem from axisymmetric convection. By decomposing the term related to power generation (induction term) of the electromagnetic induction equation into multiple component terms (each term) in cylindrical coordinates, converting these component terms to magnetic field energy, and integrating the area numerically, the possibility of increasing the magnetic field energy, which is not mentioned in Cowling's original theorem, is revealed. Notably, multiple points on the poloidal surface cooperate to generate a magnetic field. The possibility of generating a stable magnetic field is demonstrated from an energy supply perspective. Therefore, Cowling's theorem can be considered controversial. Considering the findings of this study, the research direction will change.