Local Standard of Rest

A star's velocity relative to the LSR can be divided into three components: , the velocity in/out from the center; , the velocity tangent to the orbit; and Z, the velocity perpendicular to the orbit.

By definition, the and Z components are equal to zero because the particle is moving in a uniform circular motion in the plane of the Milky Way. Thus, we want to find the component of the velocity (LSR).