ESTIMATING DISTANCES TO ELLIPTIC GALAXIES WITH A MASS-LUMINOSITY-RELATION

We argue that the physical reason for the success of the Fundamental P lane and the D-n-sigma relation as distance estimators for elliptical galaxies is the existence of a relation between luminosity and mass wi th small intrinsic scatter. Therefore a better understanding of the lu minosity and mass variables, and of the mass-luminosity relation, is n eeded to improve distance estimation for elliptical galaxies. We propo se a distance indicator in the form of a mass-luminosity relation and use it to derive modifications to the Fundamental Plane and to the D-n -sigma relation. Note that distances estimated with these modified Fun damental Plane and D-n-sigma relations may, in practice, turn out to b e less precise than those estimated with the standard relations when t he added terms have large observational errors.