2020ApJ...891...95Y

We report, for the first time, both the strengthening and radial velocity increases of a narrow absorption-line (NAL) system (C IV λλ1548, 1551 and N V λλ1239, 1243) from the two-epoch spectra of quasar SDSS J143530.49+142338.4. First, we speculate that the ionization changes of the outflow clouds are likely the cause of the strengthening in its equivalent width (EW) based on the obvious weakening of the ionization continuum, although other interpretations cannot be ruled out based on the current two-epoch spectra. According to the cloudy simulation, the asynchronized variations between the absorption-line EWs and the ionizing continuum indicate that the absorbers are at relatively high degrees of ionization, which is also consistent with the high ionization state revealed by the absence of Si IV NAL in the same system. Second, this NAL system exhibits a kinematic velocity shift of ∼138 kms^–1 within 445.2 days in the quasar rest frame (corresponding to an average acceleration of ∼0.36 cms^–2). We evaluate several possible causes for this kinematic shift. However, the current two-epoch spectra do not provide enough constraints to confirm the possible mechanisms, so future monitoring with high resolution will be helpful to achieve this goal.