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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.)

The R-Process Alliance: Chemical Abundances for a Trio of r-process-enhanced Stars-One Strong, One Moderate, and One Mild

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Autor(es):
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Cain, Madelyn [1, 2] ; Frebel, Anna [1, 2, 3] ; Gull, Maude [1, 2] ; Ji, Alexander P. [4] ; Placco, Vinicius M. [5, 3] ; Beers, Timothy C. [5, 3] ; Melendez, Jorge [6] ; Ezzeddine, Rana [1, 2, 3] ; Casey, Andrew R. [7] ; Hansen, Terese T. [4] ; Roederer, Ian U. [8, 3] ; Sakari, Charli [9, 3]
Número total de Autores: 12
Afiliação do(s) autor(es):
[1] MIT, Dept Phys, Cambridge, MA 02139 - USA
[2] MIT, Kavli Inst Astrophys & Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 - USA
[3] Joint Inst Nucl Astrophys, Ctr Evolut Elements, Notre Dame, IN 46556 - USA
[4] Carnegie Inst Washington Observ, 813 Santa Barbara St, Pasadena, CA 91101 - USA
[5] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA
[6] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo, SP - Brazil
[7] Monash Univ, Sch Phys & Astron, Monash Ctr Astrophys, Melbourne, Vic 3800 - Australia
[8] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 - USA
[9] Univ Washington, Dept Astron, Seattle, WA 98195 - USA
Número total de Afiliações: 9
Tipo de documento: Artigo Científico
Fonte: ASTROPHYSICAL JOURNAL; v. 864, n. 1 SEP 1 2018.
Citações Web of Science: 2
Resumo

We present detailed chemical abundances of three new bright (V similar to 11), extremely metal-poor ({[}Fe/H]similar to -3.0), r-process- enhanced halo red giants based on high-resolution, high-S/N Magellan/MIKE spectra. We measured abundances for 20-25 neutron- capture elements in each of our stars. J1432-4125 is among the most r-process-rich r-II stars, with {[}Eu/Fe] = +1.44 +/- 0.11. J2005-3057 is an r-I star with {[}Eu/Fe] = +0.94 +/- 0.07. J0858-0809 has {[}Eu/Fe] = +0.23 +/- 0.05 and exhibits a carbon abundance corrected for an evolutionary status of {[}C/Fe] corr = +0.76, thus adding to the small number of known carbon-enhanced r-process stars. All three stars show remarkable agreement with the scaled solar r-rocess pattern for elements above Ba, consistent with enrichment of the birth gas cloud by a neutron star merger. The abundances for Sr, Y, and Zr, however, deviate from the scaled solar pattern. This indicates that more than one distinct r-process site might be responsible for the observed neutron-capture element abundance pattern. Thorium was detected in J1432-4125 and J2005-3057. Age estimates for J1432-4125 and J2005-3057 were adopted from one of two sets of initial production ratios each by assuming the stars are old. This yielded individual ages of 12 +/- 6 Gyr and 10 +/- 6 Gyr, respectively. (AU)

Processo FAPESP: 12/24392-2 - Espectroscopia de alta precisão: impacto no estudo de planetas, estrelas, a galáxia e cosmologia
Beneficiário:Jorge Luis Melendez Moreno
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 14/18100-4 - Populações estelares na Via Láctea: bojo, halo, disco e regiões de formação de estrelas; instrumentação para espectroscopia de alta resolução
Beneficiário:Beatriz Leonor Silveira Barbuy
Linha de fomento: Auxílio à Pesquisa - Temático