 Observations of the Ca lines in stars of similar age to the Sun even show cyclic variations reminiscent of the 11 year solar cycle.By observing certain infrared lines of Ca II for the 34 superflare stars it was possible to estimate their chromospheric activity.Measurements of the same lines at points within an active region on the Sun, together with simultaneous measurements of the local magnetic field, show that there is a general relation between field and activity.