Cycles of magnetic activity in solar-type stars. The place of the Sun among the stars with different levels of coronal and chromospheric activity

The atmospheric activity of the Sun and solar-type stars is analysed involving observations from HK-project at the Mount Wilson Observatory, the California and Carnegie Planet Search Program at the Keck and Lick Observatories, and the Magellan Planet Search Program at the Las Campanas Observatory. We show that for stars of F, G and K spectral classes, the cyclic activity, similar to the 11-yr Solar cycles, is different: it becomes more prominent in K-stars. Comparative study of solar-type stars with different levels of the chromospheric and coronal activity confirms that the Sun belongs to stars with the low level of the chromospheric activity and stands apart among these stars by the minimum level of the coronal radiation and minimum flux variations of the photospheric radiation.