Extinction along Sightlines Sampled by the APO Catalog of DIBs

Abstract

Identification of molecular carriers for diffuse interstellar bands (DIBs) may stem in part from the determination of interrelated lines using the Apache Point Observatory Catalog of DIBs. However, Pearson correlations may be impacted by the number of interstellar clouds along the sightlines. The trend of extinction with distance was constrained using Bayestar19 and Gaia DR3, and clouds were identified via step-functions and extended increasing linear progressions may be indicative of traversal through dense spiral arms. Thirteen sightlines are likely observed through more than one cloud. The hypergiants HD168625 and VI Cyg 12 are contaminated by local nebulosity and circumstellar disks. New findings presented here support the reddenings cited within the Apache Point Observatory catalog of DIBs.