Orbital Decay in High-Mass X-Ray Binaries

The variation of the orbital periods found in high-mass X-ray binaries occurring over time can be explained by two models. According to the first model, orbital decay occurs due to dynamic tidal forces. The second model shows that the change occurs due to the inertia moments of a massive star during its evolution. These models are applied to LMC X-4 and Cen X-3.