Magnetic activity and its variability in the Sun and solar-like stars

The light curves of solar-like stars provide information on stellar rotation and magnetic activity thanks to active-region crossings. In this work, we investigate the temporal variation of the photometric magnetic activity of the Sun and Kepler solar-like stars. We find that the most active stars are those exhibiting the most significant variations, independently of the spectral type. This relationship was known for chromospheric activity, but here we show that photometric data have a similar behavior. Because of the bimodal rotation-period distribution, there are two regimes in the activity-rotation relation: slow- and fast-rotating branches. While stars in the fast-rotating branch tend to have higher activity levels (in general) than the slow-rotating branch, their temporal variation is consistent, with both branches following the same relationship. We also compare the Sun with Sun-like stars, a subsample with very similar properties to the Sun selected according to effective temperature, surface gravity, and rotation. While the Sun is among the less active stars (depending on the cycle’s phase), we find that the behavior of the Sun’s magnetic activity is consistent with that of Kepler Sun-like stars. Finally, we also find evidence for the metallicity impact on the rotation evolution. This kind of analysis helps improve our understanding of solar/stellar magnetism and its associated timescales. Future PLATO data will bring a new opportunity in this direction.