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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Elemental abundances and classification of carbon-enhanced metal-poor stars

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Autor(es):
Allen, D. M. [1] ; Ryan, S. G. [2, 3] ; Rossi, S. [1] ; Beers, T. C. [4, 5] ; Tsangarides, S. A. [6]
Número total de Autores: 5
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil
[2] Univ Hertfordshire, STRI, Ctr Astrophys Res, Hatfield AL10 9AB, Herts - England
[3] Univ Hertfordshire, Sch Phys Astron & Math, Hatfield AL10 9AB, Herts - England
[4] Michigan State Univ, Dept Phys & Astron, E Lansing, MI 48824 - USA
[5] Michigan State Univ, JINA, E Lansing, MI 48824 - USA
[6] Open Univ, Milton Keynes MK7 6AA, Bucks - England
Número total de Afiliações: 6
Tipo de documento: Artigo Científico
Fonte: Astronomy & Astrophysics; v. 548, DEC 2012.
Citações Web of Science: 37
Resumo

We present a detailed study of carbon-enhanced metal-poor (CEMP) stars, based on high-resolution spectroscopic observations of a sample of 18 stars. The stellar spectra for this sample were obtained at the 4.2 m William Herschel Telescope in 2001 and 2002, using the Utrecht Echelle Spectrograph, at a resolving power R similar to 52 000 and S/N similar to 40, covering the wavelength range lambda lambda 3700-5700 angstrom. The atmospheric parameters determined for this sample indicate temperatures ranging from 4750 K to 7100 K, log g from 1.5 to 4.3, and metallicities -3.0 <= {[}Fe/H]<=-1.7. Elemental abundances for C, Na, Mg, Sc, Ti, Cr, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, Eu, Gd, Dy are determined. Abundances for an additional 109 stars were taken from the literature and combined with the data of our sample. The literature sample reveals a lack of reliable abundance estimates for species that might be associated with the r-process elements for about 67% of CEMP stars, preventing a complete understanding of this class of stars, since {[}Ba/Eu] ratios are used to classify them. Although eight stars in our observed sample are also found in the literature sample, Eu abundances or limits are determined for four of these stars for the first time. From the observed correlations between C, Ba, and Eu, we argue that the CEMP-r/s class has the same astronomical origin as CEMP-s stars, highlighting the need for a more complete understanding of Eu production. (AU)

Processo FAPESP: 08/01265-0 - Análise de estrelas carbonadas pobres em metais
Beneficiário:Dinah Moreira Allen
Linha de fomento: Bolsas no Brasil - Pós-Doutorado