Spectral analysis of the sdO standard star Feige 34

TL;DR

This study conducts a detailed spectral analysis of the hot sdO star Feige 34 using optical and ultraviolet spectra, deriving its fundamental parameters and elemental abundances, revealing iron and nickel enrichment and possible stellar rotation.

Contribution

It combines high-quality optical spectra with non-LTE models and ultraviolet data to accurately determine the star's physical parameters and chemical composition, including metal enrichment.

Findings

Feige 34 has Teff = 63,000 K and log g = 6.0.

Iron and nickel are enriched tenfold relative to solar.

Spectral lines may be broadened by stellar rotation.

Abstract

We present our current work on the spectral analysis of the hot sdO star Feige 34. We combine high S/N optical spectra and fully-blanketed non-LTE model atmospheres to derive its fundamental parameters (Teff, log g) and helium abundance. Our best fits indicate Teff =63 000 K, log g=6.0 and log N(He)/N(H)=-1.8. We also use available ultraviolet spectra (IUE and FUSE) to measure metal abundances. We find the star to be enriched in iron and nickel by a factor of ten with respect to the solar values, while lighter elements have subsolar abundances. The FUSE spectrum suggests that the spectral lines could be broadened by rotation.