Variable Star Atlas - Rotational Variables
Rotational variables are stars that have a change in apparent brightness due to large spots on their surfaces. Periods for rotational variables are tied to the rotation of the stars themselves; therefore, their periods can widely vary (~0.5-100 days). The light curves for ROT variables are typically very noisy since the star spots evolve over time. Star spot cycles are complex, and we can often see the amplitude of the rotational modulation, and sometimes even the mean brightness of the star, vary over long time scales. When the amplitude is modulated you will see variations in the amount of scatter in the Mag and Flux light curves. For mean brightness changes, you will see a long term trend superimposed onto the star's short term variability cycles.