Observations of diffuse interstellar lines toward stars with low column densities of H2

The diffuse interstellar band at 5780 A has been observed in lines of sight where the column density of H2 is less than 1016 cm-2. The strength of lambda5780 toward #betta# Cas, kappa Ori, and rho Leo argues strongly against a molecular carrier of the 5780 A feature. The interstellar band at 5797 A also appears to be present in kappa Ori and rho Leo. Although the exact mechanism remains unclear, we conclude that the diffuse features at 5780 A and 5797 A are carried by dust grains