CHEMICAL COMPOSITION AND ATMOSPHERE PARAMETERS OF THE DOUBLE-MODE CEPHEID U TRA
Usenko, I. A.
Kniazev, A. Yu.
Berdnikov, L. N.
Kravtsov, V. V.
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Four high-resolution spectra of the doble-mode Cepheid U TrA have been obtained during its pulsational period. For the first time, we obtained accurate atmosphere parameters and the chemical abundance of a number of elements, in particular of sodium, magnesium, and aluminium. We estimated the mean Teff = 6085 29 K, log g = 2.00 0.15, and Vt = 3.90 0.25 kms -1 . A deficit of carbon ([C=H] = –0.35 0.23 dex), overabundance of both sodium ([Na=H] = +0.15 0.25 dex) and aluminium ([Al=H] = +0.30 0.32 dex) are typical for Cepheids passing through the first dredge-up phase. The abundance of iron ([Fe=H] = +0.01 0.15 dex) is very close to the solar one. Moreover, we find that -elements, those of Fe-group, as well as ”light”- and ”heavy”-, s- and rprocess elements, all of them have abundances close to solar values, too, excepting maybe several elements with slight enhance or deficit.