2002MNRAS.330..425B

We present Far Ultraviolet Spectroscopic Explorer (FUSE ) observations of the very hot (T_eff ~ 60000K) DA white dwarf PG1342+444, describing our data reduction and analysis techniques. The spectrum reveals a number of photospheric absorption lines from high ionization species along with numerous interstellar features. The photospheric detections include the 1031.9- and 1037.0-Å Ovi lines which are seen for the first time in a hot DA atmosphere and are usually associated with the much hotter PG1159 stars and so-called Ovi central stars of planetary nebulae. Estimates of the stellar effective temperature made independently using both the Balmer and Lyman series lines are in disagreement (T_eff ~ 67000K and ~ 54000K respectively), when taking into account just the statistical uncertainties in the analyses. However, the presence of weak absorption from the CIII multiplet near 1176Å, which is predicted to be much stronger if the star were as cool as the Lyman measurement suggests, leads us to favour the higher temperature. PG1342+444 appears to have enhanced C, Fe and Ni abundances in its atmosphere compared with all the other G191-B2B-like DA white dwarfs, which might affect the temperature structure of the atmosphere if not homogeneously distributed, as assumed in this study.