Diffuse interstellar absorption bands between 2.9 and 4.0 μm

Abstract

IRS7, the obscured M supergiant near the galactic centre, is an excellent source against which to study interstellar absorption bands near 3-μm wavelength. Previously we considered1 the 3.4-μm absorption band as evidence that interstellar grains include an organic component. We report here superior data between 2.9 and 4.0 μm, and find a broad absorption trough with numerous discrete features stretching from 2.9 to 3.6 μm. Although no definite identification of the material producing this absorption is possible, there is some indication that complex organic molecules may be involved. Show more