The EDIBLES survey. V. Line profile variations in the lambdalambda5797, 6379, and 6614 diffuse interstellar bands as a tool to constrain carrier sizes

Vol. 657
6. Interstellar and circumstellar matter

The EDIBLES survey. V. Line profile variations in the lambdalambda5797, 6379, and 6614 diffuse interstellar bands as a tool to constrain carrier sizes

This study of the high resolution profile correlations among the three strong optical diffuse interstellar bands (DIBs) along well specified sight lines is an exciting application of standard laboratory spectroscopic structural techniques to an ongoing mystery, that is to say identifying the molecular carrier species of these features. The authors find that the three DIBs have similar structures along each of the sight lines and they argue that profile changes between sources are due to varying excitation conditions. They find no obvious correlation with molecular hydrogen or C₂ excitation. With this as the starting point, and assuming the profiles are rotational bands of spherical top or linear molecules, which is a simplifying but reasonable decision, the authors derived excitation temperature ladders and rotational constants. Considering acetylenic species, cyanopolyynes, fullerenes, and planar PAH molecules as paradigms, they derived approximate compositions for the carriers of the three bands, ranging in size from the smallest for 6614Å and the largest for 6379Å .