Аннотация:Conventional scenario for cyclic solar activity in the framework of solar dynamo studies associates the cycle with joint action of differential rotation and mirror asymmetry of convective flows. The cycle duration is however very close to the orbital period of Jupiter. The idea that solar activity cycle arises due to periodic influence of Jupiter is presented for many decades in scientific literature. Experts in the topic usually accept the idea critically because the effect is very weak. It is however quite difficult to reject the idea firmly based on solar data only. We suggest using here data concerning exoplanetary systems with known type of the magnetic activity for central star. Corresponding comparison was performed in [1] to learn that the Sun provides the only known example of the star with magnetic activity cycle length closed to planetary orbital period. We stress however that planetary effect can play a role in determination of the shape of activity cycle. As a new result we present here a model where a weak planetary effect transforms a slightly subcritical stellar dynamo in a supercritical one.