SMC High-Mass X-ray binaries variability

Most systems exhibit variability on a range of timescales. This variability regulates the mass transfer to the compact object, while the compact object can, in turn, affect the donor star's behavior.

To better understand this complex interaction and the resulting X-ray properties in these systems, we define a new taxonomy for the observed super-orbital variability. This taxonomy connects to the color changes, orbital periods, and X-ray behavior of the sources. In most cases, these properties can be explained by differences between the flux of the disk around the Be star and the flux from the star itself.