SIMBAD references

In this paper, we present for the first time the discovery of the disappearance of a narrow Mg II λλ2796, 2803 absorption system from the spectra of the quasar SDSS J165501.31+260517.4 (z_e= 1.8671). This absorber is located at z_abs= 1.7877 and has a velocity offset of 8423 km/s with respect to the quasar. According to the velocity offset and the line variability, this narrow Mg II λλ2796, 2803 absorption system is likely intrinsic to the quasar. Since the corresponding UV continuum emission and the absorption lines of another narrow Mg II λλ2796, 2803 absorption system at z_abs= 1.8656 are very stable, we believe that the disappearance of the absorption system is unlikely to be caused by the change in ionization of absorption gas. Instead, it likely arises from the motion of the absorption gas across the line of sight.