Evolution of the most relevant emission lines. The colour code is the same as in Fig. 1. The vertical dashed blue and dashed-dotted red lines mark ±1700 km s⁻¹ and −500 km s⁻¹, velocities of the blue wing and the absorption trough of Paβ, respectively (in epochs #2 and #6). Grey bands indicate regions contaminated by DIBs or tellurics. The emission at −2500 km s⁻¹ in the He II–4686 column is produced by the Bowen blend.