C IV and O VI Transitions in the Region lambda lambda 1100--2000 and Examples Found in IUE Spectra of Hot Stars

Abstract

We present Ritz wavelengths for more than 130 transitions of C IV and O VI in the range λλ1100-2000 and show examples of absorption features as seen in representative examples of high-dispersion IUE spectra of very hot (∼100,000 K) nuclei of planetary nebulae, white dwarfs, and PG 1159-type stars. The regions near He II λ640 and interstellar Si II λ1260 are of particular interest because they coincide with strong C IV and O VI transitions. O VI absorptions are detected in the lUE spectrum of the nucleus of the planetary nebula NGC 7293, which suggests that this object may be a "hybrid" star with an H-rich atmosphere.