| Résumé | The study of the elemental abundances of double-lined spectroscopic binaries should provide information on the chemical differentiation of a once uniform prestellar nebula. To determine the effective temperatures and surface gravities of the primary and secondary stellar components of HR 104 and θ Aql, we used parameters derived from their orbital analyses and the requirement of equal abundances derived from Fe I and Fe II lines. For constraints we had optical region spectrophotometry for θ Aql and the large equivalent width ratios for the many spectral metal lines which were produced in both stellar atmospheres for HR 104. Since the primary stars were much brighter than the secondary stars, the abundances are considerably better determined for the primary stars. For HR 104 A we found T<inf>eff</inf> = 9875 K, log g = 4:26, and ξ = 1:7 km s−1; for HR 104 B T<inf>eff</inf> = 7200 K, log g = 4:26, and ξ = 0:6 km s−1; for θ Aql A T<inf>eff</inf> = 10400 K, log = 3:63, and ξ = 0:3 km s−1; and for θ Aql B Teff = 10250 K, log = 4:20, and ξ = 1:9 km s−1. The abundances of HR 104 A, HR 104 B, and θ Aql A are best described as the solar pattern. Those of θ Aql B suggest a weak nonmagnetic CP star pattern. While there is no trace of the Hg II 3984 line for θ Aql, the most extreme observed abundance anomalies for the secondary are those of Ca, V, Mn, and Ni. Further study of this hot marginal Am star could provide insights into the origin of the nonsolar chemical abundances. |
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