Synchronized Helicity Oscillations: A Link Between Planetary Tides and the Solar Cycle?
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Recent years have seen an increased interest in the question of whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we examine which possible physical mechanism might link the weak planetary forces with solar dynamo action. We focus on the helicity oscillations that were recently found in simulations of the current-driven, kink-type Tayler instability, which is characterized by an \(m=1\) azimuthal dependence. We show how these helicity oscillations may be resonantly excited by some \(m=2\) perturbations that reflect a tidal oscillation. Specifically, we speculate that the tidal oscillation of 11.07 years induced by the Venus–Earth–Jupiter system may lead to a 1:1 resonant excitation of the oscillation of the \(\alpha\)-effect. Finally, we recover a 22.14-year cycle of the solar dynamo in the framework of a reduced zero-dimensional \(\alpha\)–\(\Omega\) dynamo model.
KeywordsSolar cycle Models helicity Theory
This work was supported by the Deutsche Forschungsgemeinschaft in the frame of the SPP 1488 (PlanetMag), as well as by the Helmholtz-Gemeinschaft Deutscher Forschungszentren (HGF) in the frame of the Helmholtz alliance LIMTECH. Wilcox Solar Observatory data used in this study were obtained via the web site wso.stanford.edu (courtesy of J.T. Hoeksema). The sunspot data are SILSO data from the Royal Observatory of Belgium, Brussels, obtained via www.sidc.be/silso/infosnytot . F. Stefani thanks R. Arlt, A. Bonnano, A. Brandenburg, A. Choudhuri, D. Hughes, M. Gellert, G. Rüdiger, and D. Sokoloff for fruitful discussion on the solar-dynamo mechanism.
Disclosure of Potential Conflicts of Interest
The authors declare that they have no conflicts of interest.
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