naa a22 4500 510790011 CHVBK 20180411083316.0 cr unu---uuuuu 180411e20130701xx s 000 0 eng 10.1134/S1063773713070074 doi (NATIONALLICENCE)springer-10.1134/S1063773713070074 Spectroscopic studies of southern-hemisphere Cepheids: Six objects in Centaurus (V Cen, V737 Cen) and Sagittarius (BB Sgr, W Sgr, X Sgr, Y Sgr) [Elektronische Daten] [I. Usenko, A. Kniazev, L. Berdnikov, V. Kravtsov, A. Fokin] This paper is the next one in the series of our works aimed at determining the atmospheric parameters and chemical composition of southern-hemisphere Cepheids. We present the results of our study for six bright Cepheids: V Cen, V737 Cen, BB Sgr, W Sgr, X Sgr, and Y Sgr. We have analyzed 14 high-resolution spectra taken with the 1.9-m telescope at the South African Astronomical Observatory. In addition to determining the chemical composition and atmospheric parameters, we point out and discuss several features in the spectra of individual Cepheids. In particular,we have detected emission in the cores of the Hβ and Hα lines forWSgr near its maximum light, while X Sgr shows the splitting of metal absorption lines into individual components without any change of the hydrogen lines. These peculiarities can be explained by different manifestations of shock waves in the Cepheid atmospheres and by the presence of circumstellar envelopes around X Sgr and W Sgr. The chemical composition has been estimated for V737 Cen, BB Sgr, and X Sgr for the first time. On the whole, our abundance estimates for α-elements, iron-peak elements, and r- and s-process elements are close to the solar ones for all objects, carbon is underabundant, the oxygen abundance is nearly solar, the "odd” elements, Na and Al, are overabundant (except X Sgr), magnesium is underabundant for V Cen and X Sgr and overabundant for the remaining objects. Such a chemical composition is typical of yellow supergiants after the first dredge-up. Keywords: Cepheids, spectra, atmospheric parameters, chemical composition. Pleiades Publishing, Ltd., 2013 Usenko I. Astronomical Observatory, Odessa National University, Shevchenko Park, 65014, Odessa, Ukraine aut Kniazev A. South African Astronomical Observatory, P.O. Box 9, 7935, Observatory, Cape Town, South Africa aut Berdnikov L. Sternberg Astronomical Institute, Universitetskii pr. 13, 119991, Moscow, Russia aut Kravtsov V. Sternberg Astronomical Institute, Universitetskii pr. 13, 119991, Moscow, Russia aut Fokin A. Institute of Astronomy, Russian Academy of Sciences, ul. Pyatnitskaya 48, 119017, Moscow, Russia aut Astronomy Letters Springer US; http://www.springer-ny.com 39/7(2013-07-01), 432-445 1063-7737 39:7<432 2013 39 11443 https://doi.org/10.1134/S1063773713070074 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1134/S1063773713070074 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Usenko I. Astronomical Observatory, Odessa National University, Shevchenko Park, 65014, Odessa, Ukraine aut NATIONALLICENCE 700 1- Kniazev A. South African Astronomical Observatory, P.O. Box 9, 7935, Observatory, Cape Town, South Africa aut NATIONALLICENCE 700 1- Berdnikov L. Sternberg Astronomical Institute, Universitetskii pr. 13, 119991, Moscow, Russia aut NATIONALLICENCE 700 1- Kravtsov V. Sternberg Astronomical Institute, Universitetskii pr. 13, 119991, Moscow, Russia aut NATIONALLICENCE 700 1- Fokin A. Institute of Astronomy, Russian Academy of Sciences, ul. Pyatnitskaya 48, 119017, Moscow, Russia aut NATIONALLICENCE 773 0- Astronomy Letters Springer US; http://www.springer-ny.com 39/7(2013-07-01), 432-445 1063-7737 39:7<432 2013 39 11443 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer