Do Planets Affect the Behavior of the Long-term Solar Activity?

Abstract

Solar activity is a process driven by many independent but interconnected phenomena. Although the 11-year cycle is the result of operation of the dynamo mechanism, the cause of longer secular variations is not clear. In search of such a cause, it was proposed to take into account the influence of the planetary system. In order to verify the idea, we consider the action of all planets in the solar system reduced to the effect of a single barycenter. The tidal force is decomposed into radial and meridional components. The radial tidal force is too small compared to the powerful radial gravity of the Sun. The meridional force is not compensated for by solar gravity and depends on latitude. As the latitude of the barycenter changes quite slowly, the sign of this component changes over a characteristic time scale of about 5 years, during which the meridional acceleration constantly acts on the surface of the Sun. This could ultimately lead to speeds of several meters per second and, in principle, could significantly change the speeds of the meridional currents involved in generating the magnetic field. However, it turned out that the calculated speed variation does not agree with the observed periodicity of solar activity. Earlier, the relation was analyzed between the activity periods on solar-type stars and the rotation periods of exoplanets, and no correspondence was observed either. Thus, the planetary hypothesis as a cause of long-term modulation of solar activity is not confirmed.