Abstract
The authors have computed the filling factor for a sample of thirty-five galactic PN for which there are distance estimates independent of statistical arguments. They found that about half of the PN in their sample have filling factors smaller than 0.16. They found a strong correlation between the filling factor and the size of the nebula in the sense that the larger the size the smaller the filling factor. Some implications of this result are discussed. A discussion of the statistical distance scales is also given and two new ones are proposed, one based on the observed fluxes and another on the forbidden line densities.
