[bigheadfred]

Nice little video link to the inferred orbits of the central stars from the above explanation HERE

They infer their orbits using an inferometer, right?

[SunkenCiv]

It can be done that way.

http://en.wikipedia.org/wiki/Interferometry
http://en.wikipedia.org/wiki/Optical_interferometry
http://en.wikipedia.org/wiki/Very_Long_Baseline_Interferometry