Pseudo Three-dimensional Maps of the Diffuse Interstellar Band at 862 nm
  The diffuse interstellar bands (DIBs) are absorption lines observed in visual
and near infrared spectra of stars. Understanding their origin in the
interstellar medium (ISM) is one of the oldest problems in astronomical
spectroscopy, as DIBs ahave been known since 1922. In a completely new approach
to understanding DIBs, we combined information from nearly 500,000 stellar
spectra obtained by the massive spectroscopic survey RAVE (Radial Velocity
Experiment) to produce the first pseudo three-dimensional map of the strength
of the DIB at 8620~{\AA}ngstroms covering the nearest 3 kiloparsecs from the
Sun, and show that it follows our independently constructed spatial
distribution of extinction by interstellar dust along the Galactic plane.
Despite having a similar distribution in the Galactic plane, the DIB 8620
carrier has a significantly larger vertical scale height than the dust. Even if
one DIB may not represent the general DIB population, our observations outline
the future direction of DIB research.
