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The occurrence of stellar wind in central stars planetary nebulae (CSPNe) canbe revealed by the presence of P Cygni profiles of high-excitation linesoverimposed on the stellar continuum. We have examined the entire FUSE archiveand merged all useful observations of CSPNe to produce the highest qualityspectra that can be used to assess the occurrence of stellar winds.Furthermore, the individual spectra of each CSPN have been searched forvariability in the P Cygni profile. P Cygni profiles of high-excitation lineshave been found in 44 CSPNe, with a clear correlation between the lineionization potential and the star effective temperature. We introduce aprescription to derive the terminal wind velocity (v_inf) from saturated andunsaturated P Cygni profiles and provide new values of v_inf for these stars.Another 23 CSPNe do not show P Cygni profiles or their FUSE data are notconclusive to determine the occurrence of P Cygni profiles. Variability in theP Cygni profile of high-excitation far-UV lines is found for the first time insix CSPNe, namely Hen 2-131, NGC 40, NGC 1535, NGC 2392, Sp 3, and SwSt 1,increasing up to 13 the number of CSPNe with variable P Cygni profiles in theUV, including those previously reported using IUE or FUSE observations.Variability is seen preferentially in the unsaturated P V and Si IV lines, butalso in saturated C III and O VI lines. The CSPNe with variable P Cygniprofiles have similar stellar properties (relatively low log(g) and T_eff) thatsuggests they are less evolved CSPNe. Some of the CSPNe with variable P Cygniprofiles show O VI lines, while their T_eff is insufficient to produce thision. We suggest that such ion is produced by Auger ionization from X-raysassociated to shocks in their stellar winds as is the case in massive OB starsof high ionization potential ions which cannot be abundantly produced byphotoionizations.

Analysis of Far-UV Data of Central Stars of Planetary Nebulae: Occurrence and Variability of Stellar Winds