H_α spectra from 2017 December 30 to 2018 January 3. (a) Examples of Gaussian fitting for the H_α subtractions. Left part: Observed (black solid lines) and synthesized (magenta dashed lines) H_α spectra. The observing dates and phases are also marked. Right part: Gaussian fitting (colored dashed lines) for the H_α subtractions (black solid lines). All subtracted spectra are corrected to the rest velocity frame of the K0 IV primary star of UX Ari. The insets show zoomed-in images of the spectral ranges with the far-redshifted emission components. (b) Temporal variations of the EWs of the narrow and broad emission components. (c) Temporal variations of the velocities of the broad emission component and the fitting line. (d) Temporal variations of the velocities of the far-redshifted emission component and the G5 V secondary component relative to the K0 IV primary component.