Measurements of Narrow Mg II Associated Absorption Doublets with Two Observations

The measurement of the variations of absorption lines over time is a good method to study the physical conditions of absorbers. In this paper, we measure the variations of the line strength of 36 narrow Mg IIλλ2796,2803 associated absorption doublets, which are imprinted on 31 quasar spectra with two observations of the Sloan Digital Sky Survey (SDSS). The timescales of these quasar span 1.1–5.5 years at the quasar rest-frame. On these timescales, we find that these narrow Mg II associated absorption doublets are stable, with no one λ2796 line showing strength variation beyond 2 times error (2σ).