Application of non-linear analysis to intensity oscillations of the chromospheric bright points

We have applied several nonlinear techniques to the intensity oscillations of the chromospheric bright points observed at the Vacuum Tower Telescope ( VTT) of the Sacramento Peak Observatory. A 35-min time sequence obtained in the Ca II H line over a quiet region at the center of the solar disk under high spatial, spectral, and temporal resolution has been used. A relativel y new approach is used to detect the hidden periodicity and to extract the associated periodic component(s) from an apparently irregular time series. The unique feature of this approach is that the constituent component(s) ca n be non-sinusoidal in nature. The periodicity analysis shows that time ser ies of intensity oscillations of most of the bright points can be composed of two non-sinusoidal periodic components with periodicity varying between 2.4 min and 5.8 min. With the help of a multivariate embedding technique, g lobally significant spatial nonlinear correlation is found. The identificat ion of the nonlinear interaction between bright points is performed by usin g the methods of dynamical phase synchronization and the similarity index. The analysis indicates that bright points are interconnected in the sense t hat some bright points are more active and can influence the other relative ly passive bright points.