Chances and absorption features in the ultraviolet spectrum of the PG 1159-type central star RX J2117+3412

Comparison of IUE high- and low-dispersion spectra for the PG 1159-type cen tral star of RX J2117+3412 indicates that the stellar continuum level and s ome absorption features decreased between 1993 and 1995. These observed cha nges may represent a new phenomenon not previously known to occur in PG 115 9-type DO degenerates. The definite detection of O v lambda 1371 in co-adde d 1993 IUE spectra suggests that T-eff for the star may have been even high er than 170,000 K in 1993. Radial velocities and equivalent widths were mea sured for more than 60 photospheric and circumstellar/interstellar features , some of which are compared with published data obtained from HST GHRS and IUE.