Here the star is several light hours from the 3.5x106 solar mass black hole, so its orbital motion can be plotted.
These speeds can be determined by standard equations for orbital motion - let me know if you need more details.
This may be associated with the orbital motion of the white dwarf companion star.
The third is to get it in orbital motion.
"When we calculate the orbital motions of the suns and the world?"
The orbital motion of the planet will be what sends it through.
These two objects (initially) continue their orbital motion inside the common envelope.
It is this orbital motion that exhibits the phenomena with which we are concerned.
One has to use the more complex formulas that apply to orbital motion.
Yet these changes together with orbital motion affect billions of lives each year.