XMM-Newton EPIC-pn spectrum and model of the soft emitting region with a VNEI model fit (black points and solid line). The estimation of the local background spectrum and model (red points and solid line) is described in Sect. 3.2.1. The background spectrum was not subtracted from the source spectrum but was modelled simultaneously and is included in the spectral model of the source spectrum. The different spectral components are shown separately (red and black dotted lines) for the background and source spectra. The bottom panel shows the residuals from the best-fit models.