Activity period (days) versus rotation period (days). The dashed red lines represent the active branch (A), while the dashed olive lines represent the inactive branch (I). These lines were taken from the work of Metcalfe et al. (2016) and were computed for solar-type stars. The green dots correspond to some M-type stars. Blue diamonds represent the results obtained in this work based on the S-index, and red diamonds correspond to results obtained based on the Hα index.