How does vibration/motion of a star help when determining which star is closer and farther ?

For example, thats related to stellar seismology.

So if i want to identify which start is closer from 2 stars, how would motion/vibration be important?





and if i wanted to make a diagram describing why , what would i put ?



thanksyou :)How does vibration/motion of a star help when determining which star is closer and farther ?If one star moves farther in a time period than another (let's say they move at the same speed), most likely that star is closer. Not exactly sure about vibration.