Busca avançada
Ano de início
Entree
(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.)

Mn, Cu, and Zn abundances in barium stars and their correlations with neutron capture elements

Texto completo
Autor(es):
Allen, D. M. [1] ; Porto de Mello, G. F. [2]
Número total de Autores: 2
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil
[2] Univ Fed Rio de Janeiro, Observ Valongo, BR-20080090 Rio De Janeiro - Brazil
Número total de Afiliações: 2
Tipo de documento: Artigo Científico
Fonte: Astronomy & Astrophysics; v. 525, JAN 2011.
Citações Web of Science: 16
Resumo

Barium stars are optimal sites for studying the correlations between the neutron-capture elements and other species that may be depleted or enhanced, because they act as neutron seeds or poisons during the operation of the s-process. These data are necessary to help constrain the modeling of the neutron-capture paths and explain the s-process abundance curve of the solar system. Chemical abundances for a large number of barium stars with different degrees of s-process excesses, masses, metallicities, and evolutionary states are a crucial step towards this goal. We present abundances of Mn, Cu, Zn, and various light and heavy elements for a sample of barium and normal giant stars, and present correlations between abundances contributed to different degrees by the weak-s, mains, and r-processes of neutron capture, between Fe-peak elements and heavy elements. Data from the literature are also considered in order to better study the abundance pattern of peculiar stars. The stellar spectra were observed with FEROS/ESO. The stellar atmospheric parameters of the eight barium giant stars and six normal giants that we analyzed lie in the range 4300 < T(eff)/K < 5300, -0.7 < {[}Fe/H] <= 0.12 and 1.5 <= log g < 2.9. Carbon and nitrogen abundances were derived by spectral synthesis of the molecular bands of C(2), CH, and CN. For all other elements we used the atomic lines to perform the spectral synthesis. A very large scatter was found mainly for the Mn abundances when data from the literature were considered. We found that {[}Zn/Fe] correlates well with the heavy element excesses, its abundance clearly increasing as the heavy element excesses increase, a trend not shown by the {[}Cu/Fe] and {[}Mn/Fe] ratios. Also, the ratios involving Mn, Cu, and Zn and heavy elements usually show an increasing trend toward higher metallicities. Our results suggest that a larger fraction of the Zn synthesis than of Cu is owed to massive stars, and that the contribution of the main-s process to the synthesis of both elements is small. We also conclude that Mn is mostly synthesized by SN Ia, and that a non-negligible fraction of the synthesis of Mn, Cu, and Zn is owed to the weak s-process. (AU)

Processo FAPESP: 98/10138-8 - Espectroscopia de média e alta resolução: abundâncias químicas e populações estelares
Beneficiário:Beatriz Leonor Silveira Barbuy
Linha de fomento: Auxílio à Pesquisa - Regular
Processo FAPESP: 08/01265-0 - Análise de estrelas carbonadas pobres em metais
Beneficiário:Dinah Moreira Allen
Linha de fomento: Bolsas no Brasil - Pós-Doutorado