出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：Carbon is one of the most abundant metals in the universe because of its synthesis in the fundamental
3a reaction. The knowledge of carbon abundances in different environments is one key
ingredient to our understanding of stellar and galactochemical evolution. Studies of luminous
OB-type stars allow us to address both topics even in galaxies beyond our own. Unfortunately the
history of carbon abundance determinations from these objects in the last three decades is one of
limited success. Analyses of the strong and weak line spectra of C II as well as C III tend to be
largely discrepant. We present results of quantitative spectral analyses based on a sophisticated
model atom for non-LTE line-formation calculations of C II-IV. As a first application, carbon
abundances in a sample of B-type dwarfs and giants in nearby associations and in the field are
determined. Consistency is finally achieved for all measurable lines from the three ionization
stages. This includes in particular the notorious C II ll 4267 and 6578/6582 Å features which
are highly important for abundance determinations of fast-rotating and extragalactic objects. The
long-standing problem of carbon line formation can now be regarded as solved, with the previous
difficulties related to the use of inaccurate atomic data and stellar parameters. A highly homogeneous
and slightly sub-solar present-day carbon abundance from young stars in the solar vicinity
of log C/H+ 12 = 8.32±0.04 is derived.
