Evidence for large organic molecules in the diffuse medium using optical high resolution spectroscopy

The Diffuse Interstellar Bands (DIBs) are absorption lines observed in the line of sight toward reddened OB stars. Their ubiquitous detection in space indicates chemically stable and abundant carriers. High resolution spectroscopy led to the detection of substructures in the line profiles of a few DIBs, indicating a gas phase molecular origin of the carriers. Line profile studies are useful tools to derive information on the band carriers nature. In this paper we compared the velocity structure of the λ6613 Å DIB line profile to the NaD ₁ and CaII profiles toward 6 targets of the Perseus OB2 association.