An abundance analysis of the primary star of the peculiar eclipsing binary ε aurigae out of the eclipsing phase

摘要

A detailed abundance analysis of the primary star of ε Aur before an eclipse was carried out using a very high signal-to-noise ratio optical-region spectrum. An A7 Iab supergiant HD 81471, presumably a member of the Vela OB1 association, was used as a reference. We obtained atmospheric parameters (T _(eff), logg, and ξ_t) to be (8025K, 1.0 and 10 km s ~(-1)) and (8050K, 1.0 and 7 kms~(-1) for ε Aur and HD 81471, respectively. The abundances of Mg, Si, S, Ca, Sc, Ti, Cr, and Fe were very close to the solar abundances in both stars. Light elements C and O were under-abundant, while N and Na were over-abundant in both stars, after correcting for non-LTE effects. Definite under-abundances of Sr were detected in both stars. Slight, but definite, over-abundances were found in ε Aur for the s-process elements Y, Zr, and Ba, when compared with the results of HD 81471. Enhancements in the abundances of N, Na, and s-process elements might indicate the occurences of thermal dredge-up and the s-process nucleosynthesis in ε Aur during the past evolution.