Axisymmetric Magnetic Fields can be Stably Generated via Simple Convection

抄録

Researchers have struggled to understand the mechanism underlying the formation of celestial magnetic fields. To avoid constraints such as Cowling's theorem, several studies have set up complex convection and developed theories for magnetic field generation. Research in this field could progress through the discovery of a simple mechanism. This paper pursues the power generation theory of a simple mechanism that generates a coaxial magnetic field by axisymmetric convection in a conductive fluid. Whether this power generation can be stably maintained depends on whether there is a source of power generation in the induction term. This problem can be solved by decomposing and examining the induction term in detail. Cowling's theory omits certain components (additional terms) from this term; however, in this study, these components are determined to be essential for axisymmetric magnetic field generation based on calculations and examination of the total amount of regional energy. This approach is a novel concept. In addition, another claim of Cowling's theorem concerning the neutral point is also disputed. Consequently, even under simple axisymmetric convection, the possibility of generating axisymmetric magnetic fields is demonstrated. These findings will contribute to further elucidation of the mechanism of magnetic field formation.