Velocity offset, FWHM, and luminosity evolution of the blue component (BC), central component (CC), and red component (RC) of Hα. The fits of the X-shooter spectra are shown in a darker shade and are connected with dot-dashed lines, while the fits to lower-resolution spectra are shown with lighter markers. The red component is more luminous by a factor of 10 and does not evolve in velocity or FWHM, while the blue component moves towards the red and eventually disappears. Note that the data points in the grey-shaded region are measured for the HV emission feature at the absorption trough of C IIλ6580 assuming they are related to the blue component of Hα. The 107.6 d spectrum was fit only for the blue component as the red component was not describable with a symmetric line profile (as at 121.3 d; see Fig. 4). The shown uncertainties are 2σ estimated by the Markov chain Monte Carlo emcee package (Foreman-Mackey et al. 2012) as implemented by LMFIT.