1995A&AS..110..353P

All the high resolution spectra of central stars of Planetary Nebulae (CSPN) obtained so far with the SWP camera of the IUE satellite have been examined for variability in their P Cygni profiles. The available data allowed to explore the constancy or changes of the line profiles in fourteen CSPN over time scales of months to various years. In nine of them (NGC 40, 246, 6210, 6572, 7009, IC 418, IC 2149, BD +30 3639 and Lo 8) no appreciable changes have been seen, while flux variations up to 50% or so in portions of the profiles have been observed in NGC 1535, 2392, 6826 and IC 4593. In NGC 6543 a photometric variability is suggested. It is not possible at present to conclude about changes in the P Cygni profiles in the central star of NGC 6543. Sometimes moderate changes in the edge velocity have been noted. There is a good correlation between spectral changes in the optical and in the UV ranges, in the sense that most of the stars we found to change in the UV have been reported to change in the optical.