The Atmospheres of the B Stars. III. The Composition of Tau Scorpii.
Abstract
New measurements of line intensities in the spectrum of r Scorp , based on coude' plates secured at the Mount Wilson and McDonald Ohservatories, are discussed with the aid of a model atmosphere and Pecker's theory for medium-strong lines. The computational procedures are described in detail, with a view to their application to other stellar atmospheres. he abundances derived differ from those and by Traving for three reasons: (1) the newer equivalent widths differ systematically from those found with the older McDonald spectrographs; (2) a slightly different model atmosphere is employed; and (3) a precise theory of line formation is utilized. Different ions of the same element yield different curves of growth, whereas lines formed in the same layers tend to have similar curves of growth. The agreement between theory and observation is improved with the aid of a differential correction to the model atmosphere, but all ions of all elements cannot be equally well represented by the same model atmosphere. The largest uncertainties appear to come from poor f-values. Helium, carbon, nitrogen, oxygen, and silicon are observed in two stages of ionization; other elements are observed in only one stage of ionization.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- March 1957
- DOI:
- 10.1086/190030
- Bibcode:
- 1957ApJS....3....1A