The diffuse interstellar band around 8620 {\AA} II. Kinematics and distance of the DIB carrier

We aim to make use of the measurements from the Giraffe Inner Bulge Survey (GIBS) and the Gaia$-$ESO survey (GES) to study the kinematics and distance of the carrier of DIB$\,\lambda$8620, as well as other properties. We successfully detected and measured DIB$\,\lambda$8620 in 760 of 4117 GES spectra. Combined with the DIBs measured in GIBS spectra, we confirmed a tight relation between EW and $E(J-K_{\rm S})$ as well as $A_{\rm V}$, with similar fitting coefficients to those found by previous works. With a more accurate sample and the consideration of the solar motion, the rest-frame wavelength of DIB$\,\lambda$8620 was redetermined as 8620.83 A, with a mean fit error of 0.36 A. We studied the kinematics of the DIB carriers by tracing their median radial velocities in each field in the local standard of rest ($V_{\rm LSR}$) and into the galactocentric frame ($V_{\rm GC}$), respectively, as a function of the Galactic longitudes. Based on the median $V_{\rm LSR}$ and two Galactic rotation models, we obtained valid kinematic distances of the DIB carriers for nine GIBS and ten GES fields. We also found a linear relation between the DIB$\,\lambda$8620 measured in this work and the near-infrared DIB in APOGEE spectra at $1.5273\,\mu m$. We demonstrate that the DIB carriers can be located much closer to the observer than the background stars based on the following arguments: (i) qualitatively, the carriers occupy in the Galactic longitude$-$velocity diagram typical rotation velocities of stars in the local Galactic disk, while the background stars in the GIBS survey are mainly located in the Galactic bulge; (ii) quantitatively, all the derived kinematic distances of the DIB carriers are smaller than the median distances to background stars in each field.