New Infrared Diffuse Interstellar Bands in the Galactic Center and Elsewhere

Abstract

AbstractThis paper updates the recent discovery of over a dozen new diffuse interstellar bands (DIBs), first in H-band spectra of stars in the Galactic center (GC) and toward stars in the Cygnus OB2 Association. The H-band DIBs, which currently number 15, are the longest wavelength DIBs reported to date and are the first found on sightlines toward the Galactic center. K-band (2.0-2.5 μm) spectra of the GC stars do not reveal additional DIBs. Comparison of the velocity profile of the strongest of the new DIBs in the sightline toward GCS3-2 (in the GC) with that toward Cygnus OB2 No. 9 and also with the broad velocity profiles of H3+ lines toward GCS3-2 confirm that a significant fraction of the diffuse material producing the DIB absorptions on sightlines to the GC is located within the central few hundred parsecs of the Galaxy.