Top panel: IRAS F05189-2524 nuclear spectrum (black curve) extracted from a circular aperture with r < 0.4″. The corresponding pPXF best-fit model profile is shown in orange. The continuum-subtracted spectrum (blue curve) is obtained by subtracting the best-fit pPXF model from the original spectrum. The vertical blue lines mark the wavelengths of the emission lines detected in the spectrum, and the vertical green lines mark the position of stellar absorption systems (i.e. from left to right: MgI triplet, Na ID and KI doublets, CaII triplet). The regions excluded from the pPXF fit and corresponding to the most intense sky line residuals are highlighted as orange shaded areas; the portions of the spectra around 5700 Å are missing because a filter blocked the laser contamination. The inset in the top panel shows the red stellar continuum emission map in the vicinity of the nuclear regions with HST/F160W contours as in Fig. C.13; the nuclear position is shown with a white marker. Bottom insets: multi-component best-fit analysis results for the main emission (Hβ and [O III], left; Hα, [N II] and [S II], right) and absorption (Na ID, centre) line features. Na ID multi-component best-fit curves required to reproduce the cool, neutral absorption are superimposed on the observed spectrum (black curve); emission components are shifted downward for the sake of clarity.