Changes and Absorption Features in the Ultraviolet Spectrum of the PG 1159-Type Central Star RX J2117+3412

Abstract

Comparison of IUE high- and low-dispersion spectra for the PG 1159-type central star of RX J2117+3412 indicates that the stellar continuum level and some absorption features decreased between 1993 and 1995. These observed changes may represent a new phenomenon not previously known to occur in PG 1159-type DO degenerates. The definite detection of O V λ1371 in co-added 1993 IUE spectra suggests that T_eff for the star may have been even higher than 170,000 K in 1993. Radial velocities and equivalent widths were measured for more than 60 photospheric and circumstellar/interstellar features, some of which are compared with published data obtained from HST GHRS and IUE.