 When both rates of movement are known , the space velocity of the star relative to the Sun or the galaxy can be computed . Among nearby stars , it has been found that younger population I stars have generally lower velocities than older , population II stars . The latter have elliptical orbits that are inclined to the plane of the galaxy . A comparison of the kinematics of nearby stars has allowed astronomers to trace their origin to common points in giant molecular clouds , and are referred to as stellar associations . 
 When both rates of movement are known , the space velocity of the star relative to the Sun or the galaxy can be computed . Among nearby stars , it <a href='been_done' title='1'><mark>has</mark></a> been found that younger population I <a href='uninflect' title='2'><mark>stars</mark></a> have generally lower velocities than older , population II stars . The latter <a href='got' title='3'><mark>have</mark></a> elliptical orbits <a href='null_relcl' title='4'><mark>that</mark></a><a href='drop_aux' title='5'><mark>are</mark></a>inclined to the plane of the galaxy . A comparison of the kinematics of nearby stars <a href='been_done' title='6'><mark>has</mark></a> allowed astronomers to trace their origin to common points in giant molecular clouds , and are referred to as stellar associations . 
When both rates of movement r known , da space velocity of tdastar relative to the Sun or thdaalaxy can b computed . Among nearby stars , it done been found that younger population I star have generally lower velocities than older , population II stars . The latter got elliptical orbits inclined to the plane of thedalaxy . A comparison of the kinematics of nearby stars done allowed astronomers to trace their origin to common points in giant molecular clouds , and are referred to as stellar associations .