A High-Resolution Study of Near-Infrared Diffuse Interstellar Bands
  We present high-resolution echelle spectroscopic observations of the two
near- infrared (NIR) Diffuse Interstellar Bands (DIBs) at 13175 A and 11797.5
A. The DIBs have been observed in a number of diffuse interstellar medium
sightlines that exhibit a wide range of visual extinctions. Band profiles are
similar to those seen in narrow DIBs, clearly asymmetric and can be closely
fitted in most cases using two simple Gaussian components. Gaussian fits were
generally found to be more successful than fits based on a multiple-cloud model
using a template DIB profile. For a sample of 9 objects in which both bands are
observed, the strength of both NIR DIBs generally increases with A(V), and we
report a correlation between the two observed bands over a large A(V) range and
widely-separated lines of sight. The strength of the two bands is also compared
against those of two visual DIBs and the diffuse ISM aliphatic dust absorption
feature at 3.4 microns previously detected in the same sightlines. We find that
the NIR DIBs do not exhibit notable (anti)correlations with either.
Implications of these observations on possible DIB carrier species are
discussed.
