The $\lambda$6614 diffuse interstellar absorption band: evidence for
  internal excitation of the carrier
  An analysis of absorption profiles of the $\lambda$6614 diffuse interstellar
band recorded along the lines-of-sight towards HD 179406 (20 Aql) and HD 147889
is described. The difference in band shape is attributed to the degree of
internal excitation of the carrier, which is principally due to vibrational hot
bands although an electronic component may also be present. The results are
discussed with respect to other models of diffuse band spectral line shape.
