The chemical composition of algol systems. III - Beta Lyrae-nucleosynthesis revealed

Abstract

The B8 primary of the eclipsing binary star Beta Lyr is subjected to high S/N ratio Reticon observations of the visible and near-IR lines of He, C, N, O, Ne, and Fe, in order to determine their abundances. N is noted to be extremely overabundant (20 times more so than in the sun); C and O are very overabundant relative to N. The resulting C/N and O/N ratios of respectively 5 and 8 are sufficiently close to the equilibrium ratios of the CNO cycle as to leave little doubt that the material has been fully processed by the CNO cycle. The spectroscopic evidence found for He enrichment and extreme CNO cycling confirms the major compositional changes demanded by the theory of nuclear burning, thereby supporting current understanding of Beta Lyr.