Tracing Galactic Arm with 6614 Å Diffuse Interstellar Band and Gaia DR2 Distances
Abstract
Enigmatic problem in astronomical spectroscopy is diffuse interstellar bands (DIBs). DIBs are ∼ 500 weak and broad absorption features seen in the spectra of stars or other astronomical objects located behind interstellar materials. Despite the unknown ions or molecules that caused the absorptions, except for two near infrared DIBs, DIBs can be used as a potential interstellar medium (ISM) tracer to map Galactic structure. Gaia is a mission of the European Space Agency (ESA) which was launched on 2013. It provides precise distances which greatly improve our knowledge of the structure and history of our Galaxy. In this work, we used previously determined DIB equivalent width (EW) measurements by means of DIB fitting that is a combination of a synthetic stellar spectrum, a synthetic telluric transmission, and empirical DIB profile to the Gaia-ESO Large Public Spectroscopic Survey data. From DIB measurements from stellar spectra of distributed target stars and together with Gaia DR2 distances, we investigated the ISM distribution along particular line of sight, i.e., (l,b)∼(213°, -2°) which probes Local and Perseus Arm.