These variations in arrival time of the pulses were attributed to the Doppler effect caused by orbital motion of the source, and were therefore evidence for the binary nature of Centaurus X-3.

This was partly because Cen X-3 lies in the plane of the Galaxy in the direction of the Carina Spiral Arm, and so observations were forced to differentiate among dozens of faint objects.

Centaurus X-3 was finally identified with a faint, heavily reddened variable star lying just outside the error box predicted by Uhuru observations.

The overflowing gas probably forms an accretion disc and ultimately spirals inwards and falls onto the neutron star, releasing gravitational potential energy.

There is little doubt as to the correctness of the optical candidate, since it is in apparent agreement with the period and phase of Cen X-3, and exhibits the same similarity in its double wave and amplitude light curve seen in other known massive binary systems.

The double wave ellipsoidal light variations are produced by a tidally deformed giant that nearly fills its Roche lobe.