As in Fig. 7, but here the four highest signal-to-noise ratio late-time spectra are plotted around the wavelength range of Hα (left panel) and [O I] λλ6300, 6364 (right panel). For Hα, a triple Gaussian fit (green line for the total fit; blue, red, and magenta for the single components) is performed to discuss the late-time asymmetry of the line. For [O I] λλ6300, 6364, we used two Gaussians (a blueshifted and a redshifted component) for each of the two lines (6300 and 6364 Å). The normalisation of the two lines was fixed so that the 6300 Å line has three times the flux of the 6364 Å line. The centroids of the corresponding components of the two lines were fixed to be 64 Å apart.