FUSE observations of hot white dwarfs

We have analyzed FUSE observations of six hot white dwarf stars: four DA white dwarfs with Teff >∼ 45 000 K, the DAO Feige 55 (Teff ≈ 55 000 K), and the DA CD−38◦ 10980 (Teff ≈ 24 000 K). Photospheric lines from Si IV, PV, and S VI can be observed in the majority of the five hotter objects. Feige 55 shows also several other heavier elements. The measured abundances agree only partly with the predictions of the radiative levitation theory. We attribute this to current limitations of the models and the probable presence of mass loss. In the spectrum of CD−38◦ 10980, we have observed the quasi-molecular satellites of Lβ. This confirms theoretical predictions about the visibility range for these features.