Diffuse interstellar bands as probes of small-scale interstellar structure

Abstract

We present observations which probe the small-scale structure of the interstellar medium using diffuse interstellar bands (DIBs). Towards HD 168075/6 in the Eagle Nebula, significant differences in DIB absorption are found between the two lines of sight, which are separated by 0.25 pc, and λ 5797 exhibits a velocity shift. Similar data are presented for four stars in the μ Sgr system. We also present a search for variations in DIB absorption towards κ Vel, where the atomic lines are known to vary on scales of ∼ 10 AU. Observations separated by ∼ 9 yr yielded no evidence for changes in DIB absorption strength over this scale, but do reveal an unusual DIB spectrum. Copyright © International Astronomical Union 2014.