Left: XMM-Newton/RGS first and second order spectra extracted with a 3′ cross-dispersion aperture (see Fig. 1). The RGS 1 and RGS 2 data are combined for clarity. Each order is fitted separately with a 2T_SPEX model. Channels with significantly lower counts (originating from gaps in the detector plane) are accounted for in the fits but ignored in the plot for clarity. Right: XRISM/Resolve full-array spectrum fitted with a 2T_SPEX model (Sect. 2.2.1) with the two thermal components and the NXB shown separately. A zoomed-in version of this plot is displayed in Fig. D.1. We also show the most prominent emission lines, colour-coded by their astrophysical origin: AGB (left panel only), SNcc and SNIa (both panels).