Profiles of the Hα emission line. Panels a–c: high-resolution spectra of IC 4997 between 6450 and 6670 Å at the three epochs. The spectra are normalized to the intensity peak of the Hα emission line in each epoch and are shown at two different scales. Panel a marks the observed emission lines and the [N II] HVC detected in 1993 (see also Fig. 3). Panel d: spectra at the three epochs between 6473 and 6649.5 Å, arbitrarily shifted vertically. The 1993 spectrum is adapted from MTE96 and covers from 6542 Å. The horizontal line associated with each spectrum represents the stellar continuum extrapolated from line-free regions. The absorption at ∼6637.8 Å in the 2019 and 2020 spectra d does not correspond to the O Iλ1027 Å Raman feature identified in Orion (Henney 2021) and could be telluric.