Exploring the photometric signatures of magnetospheres around helium-strong stars

The photometric variations due to magnetically confined material around He-strong stars are investigated within the framework of the Rigidly Rotating Magnetosphere (RRM) model. For dipole field topologies, the model is used to explore how the morphology of light curves evolves in response to changes to the observer inclination, magnetic obliquity, rotation rate and optical depth. The general result is that double-minimum light curves arise when the obliquity and/or inclination are close to 90◦; no light variations are seen in the opposite limit; and for intermediate cases, single-minimum light curves occur. These findings are interpreted with the aid of a simple, analytical torus model, paving the way for the development of new photometric-based constraints on the fundamental parameters of He-strong stars. Illustrative applications to five stars in the class are presented.