Hα line and photometric variability in magnetically active stars

The spatial association and evolution of photospheric and chromospheric active regions, on the Sun, traces the emersion of magnetic flux tubes. We show that atmospheric phenomena observed in solar-like stars can be interpreted in terms of solar structures, once we have ascertained how detailed solar surface structures do manifest observing the Sun as a star. Low and high resolution Her spectroscopy is being performed concurrently with the systematic photometric monitoring of active RS CVn binaries at Catania Observatory, to investigate the active regions evolution at photospheric and chromospheric levels, with cycle, rotation rate and stellar parameters. Preliminary results on the photometric and Her monitoring of some active binaries, here reported, show that the rotational modulation of the H alpha emission is sometime lost, but, whenever present it is always in anti-phase with the photometric wave. We also find evidence that spots generally lead chromospheric plages by about 30-50 degrees.