Abstract

For more than 60 years, scientists have speculated about the origin of the so- called diffuse optical interstellar bands (DIBs), a complex pattern of more than 200 absorption bands of varying widths appearing in the visible part of the spectrum in the frequency-dispersed light from reddened bright stars. Previously published suggestions for DIB carriers include inorganic impurities in grains, ions of polycyclic aromatic hydrocarbons (PAHs), large linear carbonaceous unsaturated molecules, fullerenes, very large organic molecules related to life (such as porphyrins and chlorophylls), and even alien bacteria (Hoyle). With use of a model based on nonlinear absorption by H₂, we believe that we are en route to a solution of this mystery.

© 1996 Optical Society of America