ASTA02H3 Lecture 7: Proper Motion of Stars
Document Summary
Stars moving exactly towards or away from us will show no proper motions: The amount of proper motion shown by a star depends on its distance. More distant stars tend to have smaller proper motions. Can usually only measure proper motions within about 1000 parsecs of the sun. Radial velocity: how fast a star is moving directly towards or away from us. Radial velocities are measured using the doppler effect of the star"s spectrum. Star moving across our line of sight: no shift. In all cases, the radial velocity is independent of distant. Most useful when measure for many stars. Use statistics of the motions to find: motion of the sun through nearby space, location rotation of the galactic plane. Identify odd-ball stars that move peculiarly" relative to otherwise similar stars. Stellar motions are an important tool for studying the structure of our home galaxy, the milky way. Masses are measured by using the effects of gravity on objects.
