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We analysed UV FUSE, IUE, and HST/STIS spectra of five of the hottest[WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb6, and Sand 3. The analysis leveraged on our grid of CMFGEN synthetic spectra,which covers the parameter regime of hydrogen deficient central stars ofplanetary nebulae and allows a uniform and systematic study of the stellarspectra. The stellar atmosphere models calculated by us include many elementsand ionic species neglected in previous analyses, which allowed us to improvethe fits to the observed spectra considerably and provided an additionaldiagnostic line: the Ne VII $\lambda$ 973 $\mathrm{\AA}$, which had not beenmodelled in [WCE] spectra and which presents, in these stars, a strong P-Cygniprofile. We report newly derived photospheric and wind parameters and elementalabundances. The central stars of NGC 2867, NGC 5189, and Pb 6 had theirtemperatures revised upward in comparison with previous investigations and wefound the carbon to helium mass ratio of the sample objects to span a widerange of values, 0.42$\leq$C:He$\leq$1.96. Modelling of the Ne VII $\lambda$973 $\mathrm{\AA}$ P-Cygni profile indicated strong neon overabundances for thecentral stars of NGC 2867, NGC 5189, NGC 6905, and Pb 6, with Ne mass fractionsbetween 0.01 and 0.04. Nitrogen abundances derived by us for the central starsof NGC 5189, Pb 6, and Sand 3 are higher than previous determinations byfactors of 3, 10, and 14, respectively.

UV spectral analysis of very hot H-deficient [WCE]-type central stars of planetary nebulae: NGC 2867, NGC 5189, NGC 6905, Pb 6, and Sand 3