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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.)

METAL-POOR STARS OBSERVED WITH THE MAGELLAN TELESCOPE. I. CONSTRAINTS ON PROGENITOR MASS AND METALLICITY OF AGB STARS UNDERGOING s-PROCESS NUCLEOSYNTHESIS

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Autor(es):
Placco, Vinicius M. [1, 2] ; Frebel, Anna [3, 4] ; Beers, Timothy C. [1] ; Karakas, Amanda I. [5] ; Kennedy, Catherine R. [5] ; Rossi, Silvia [2] ; Christlieb, Norbert [6] ; Stancliffe, Richard J. [7]
Número total de Autores: 8
Afiliação do(s) autor(es):
[1] Natl Opt Astron Observ, Tucson, AZ 85719 - USA
[2] Univ Sao Paulo, Dept Astron, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil
[3] MIT, Cambridge, MA 02139 - USA
[4] Kavli Inst Astrophys & Space Res, Cambridge, MA 02139 - USA
[5] Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT 2611 - Australia
[6] Heidelberg Univ, Zentrum Astron, Landessternwarte, D-69117 Heidelberg - Germany
[7] Univ Bonn, Argelander Inst Astron, D-53121 Bonn - Germany
Número total de Afiliações: 7
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 770, n. 2 JUN 20 2013.
Citações Web of Science: 36
Resumo

We present a comprehensive abundance analysis of two newly discovered carbon-enhanced metal-poor (CEMP) stars. HE 2138-3336 is a s-process-rich star with {[}Fe/H] = -2.79, and has the highest {[}Pb/Fe] abundance ratio measured thus far, if non-local thermodynamic equilibrium corrections are included ({[}Pb/Fe] = +3.84). HE 2258-6358, with {[}Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R similar to 2000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements in each star, based on high-resolution (R similar to 30,000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical asymptotic giant branch (AGB) nucleosynthesis models of 1.3 M-circle dot with {[}Fe/H] = -2.5 and -2.8, as well as to a set of AGB models of 1.0 to 6.0 M-circle dot at {[}Fe/H] = -2.3. The agreement with the model predictions suggests that the neutron-capture material in HE 2138-3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE 2258-6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 <= M(M-circle dot) <= 1.3) and metallicities (-2.8 <= {[}Fe/H] <= -2.5) yield the best agreement with our observed elemental abundance patterns. (AU)

Processo FAPESP: 12/13722-1 - (Re)Descoberta e análise de estrelas pobres em metais na Via Láctea
Beneficiário:Vinicius Moris Placco
Linha de fomento: Bolsas no Exterior - Estágio de Pesquisa - Pós-Doutorado
Processo FAPESP: 10/08996-0 - O Halo da Via Láctea Revisitado
Beneficiário:Vinicius Moris Placco
Linha de fomento: Bolsas no Brasil - Pós-Doutorado