A long term, generally irregular modulation of light curves of a large subclass of RR Lyrae stars. Most of the modulations occur on the time scale of some 60 periods, although the range extends from s
ome tens to some hundreds of periods. Since its discovery over a hundred years ago, a number of explanations have been proposed for this effect, but its nature is still a matter of investigation. The explanations include: closely spaced pulsation modes, a modal 1:2 resonance, an oblique rotator model, a non-radial modal interaction, convective cycles, and nonlinear resonant mode coupling between the 9th overtone and the fundamental mode.
A long term, generally irregular modulation of light curves of a large subclass of RR Lyrae stars. Most of the modulations occur on the time scale of some 60 periods, although the range extends from s
ome tens to some hundreds of periods. Since its discovery over a hundred years ago, a number of explanations have been proposed for this effect, but its nature is still a matter of investigation. The explanations include: closely spaced pulsation modes, a modal 1:2 resonance, an oblique rotator model, a non-radial modal interaction, convective cycles, and nonlinear resonant mode coupling between the 9th overtone and the fundamental mode.