Shapes of spectral line bisectors for cool stars

The shape of the line bisector for the prototype spectral line Fe I lambda 6253 was measured for an array of 54 stars on the cool half of the HR diagram. These bisectors are given in tables along with their errors. The classic C shape is shown by only a rather restricted range in effective temperature and luminosity. The detailed change in bisector shape with effective temperature and luminosity is documented more precisely than in previous work. The most blueward point on the bisector changes its height systematically with luminosity and can be used as a luminosity or gravity discriminant. The wide range of bisector shapes contains significant information about the velocity fields in the atmospheres of these stars, but extracting that information may require extensive modeling.