Pseudo Three-dimensional Maps of the Diffuse Interstellar Band at 862 nm

TL;DR

This paper presents the first pseudo three-dimensional map of the DIB at 862 nm using nearly 500,000 stellar spectra from the RAVE survey, revealing its spatial distribution and relation to interstellar dust.

Contribution

It introduces a novel method combining large spectroscopic data to map DIBs in 3D, providing new insights into their spatial distribution in the Milky Way.

Findings

DIB at 862 nm follows the dust distribution in the Galactic plane.

The DIB carrier has a larger vertical scale height than dust.

The approach opens new directions for DIB research.

Abstract

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.