Observational constraints on the ERE interpretation

Empirical relationships on the properties of the Extended Red Emission (ERE) are presented. They are based on published observational data and on new results obtained on reflection nebulae illuminated by cold stars. The plot of the width versus the central wavelength of the ERE band is in agreement with laboratory properties of the materials commonly proposed as the ERE carriers. But this is not the case for the plot of the ERE band width versus the effective temperature of the nebula illuminating star.