The Gaia-ESO Survey: Tracing interstellar extinction

Context. Large spectroscopic surveys have in recent years enabled computing three-dimensional interstellar extinction maps thanks to the accurate stellar atmospheric parameters and line-of-sight distances these surveys provide. Interstellar extinction maps are complementary to 3D maps extracted from photometry and allow a more thorough studying of the dust properties. Aims. Our goal is to use the high-resolution spectroscopic survey Gaia-ESO to obtain with a good distance resolution the interstellar extinction and its dependency as a function of the environment and the Galactocentric position. Methods. We used the stellar atmospheric parameters of more than 5000 stars, obtained from the Gaia-ESO survey second internal data release, and combined them with optical (SDSS) and near-infrared (VISTA) photometry as well as different sets of theoretical stellar isochrones to calculate line-of-sight extinction and distances. The extinction coefficients were then compared with the literature to discuss their dependency on the stellar parameters and position in the Galaxy. Results. Within the errors of our method, our work does not show any dependence of the interstellar extinction coefficient on the stellar atmospheric parameters. We find no evidence of a variation of E(J - H) = E(J - K) with the angle from the Galactic centre or with Galactocentric distance. This suggests that we are dealing with a uniform extinction law in the SDSS ugriz bands and the near-IR JHKs bands. Therefore, extinction maps built from mean colour-excesses that assume a constant extinction coefficient can be used without introducing any systematic errors.