However, starlight is polarized, and other objects can exhibit very complex and systematic polarization behavior. X. Stars 1. The location of a star is specified by giving its direction and distance. Coordinates given are right ascension and declination, which have already been extensively discussed. As we will see, distance is needed to find out most things of real significance about stars and galaxies.
Stars move in space relative to the sun.
The radial velocity can be determined from the Doppler shift without knowing the star's distance. Under certain special circumstances, a star's motion may be used to infer its distance. The angle between a given star and the convergent point is the angle of that star's space velocity to the line of sight, which in this special case is now known. For much of the 20th century our distance scale has been based on distances to the Hyades cluster determined in this way. This quantity is often called the bolometric luminosity to distinguish it from similar quantities that refer to one or to a restricted range of wavelengths.