Discovery of Iron in PG1159 Stars

Abstract

The lack of FeVII lines in PG1159 stars had led to the conclusion that in some objects iron must be strongly depleted. We have now detected FeX lines in FUSE spectra of the very hottest PG1159 stars Teff=150,000 - 200,000 K; RXJ2117.1+3412, K1-16, NGC 246, Longmore 4). Surprisingly, we derive a solar iron abundance. It is conspicuous that they are among the most massive PG1159 stars (0.71-0.82 Msun), in contrast to those objects for which strongest Fe-deficiency was claimed (0.53-0.56 Msun). Based on new FeVIII line identifications in SOHO/SUMER UV spectra of the Sun, we were able to detect these lines in FUSE spectra of several "cooler" (Teff<150,000 K) objects, among them is the prototype PG1159-035. An abundance analysis is in progress.