Accurate Quantitative Spectroscopy of OB Stars: the H, He and C Spectrum

Abstract

We present a state-of-the-art analysis technique able to reproduce the H, He and C spectra of OB-type stars simultaneously in the visual and the near-IR. Our spectrum synthesis relies on a hybrid non-LTE approach involving robust model atoms based on precise atomic data. Highly accurate atmospheric parameters free of systematic error are derived for a sample of randomly selected apparently slow-rotating stars in the solar vicinity. A mean carbon abundance of 8.33 ± 0.04 is indicated. Up to 40 features from CII-IV are considered. This includes the prominent CII λλ4267 and 6578/82 Å lines, suitable for abundance determinations in fast-rotating and extragalactic objects at lower S/N. An excellent starting point for future highly-precise abundance analyses of other metals is established, allowing to put tight constraints on stellar and galactochemical evolution.