| Texto completo | |
| Autor(es): |
Fishlock, C. K.
;
Yong, D.
;
Karakas, A. I.
;
Alves-Brito, A.
;
Melendez, J.
;
Nissen, P. E.
;
Kobayashi, C.
;
Casey, A. R.
Número total de Autores: 8
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Monthly Notices of the Royal Astronomical Society; v. 466, n. 4, p. 4672-4682, MAY 2017. |
| Citações Web of Science: | 8 |
| Resumo | |
We determine relative abundance ratios for the neutron-capture elements Zr, La, Ce, Nd and Eu for a sample of 27 Galactic dwarf stars with -1.5 < {[}Fe/H] < -0.8. We also measure the iron-peak element Sc. These stars separate into three populations (low-and high-a halo and thick-disc stars) based on the {[}alpha/Fe] abundance ratio and their kinematics as discovered by Nissen \& Schuster. We find differences between the low-and high-alpha groups in the abundance ratios of {[}Sc/Fe], {[}Zr/Fe], {[}La/Zr], {[}Y/Eu] and {[}Ba/Eu] when including Y and Ba from Nissen \& Schuster. For all ratios except {[}La/Zr], the low-alpha stars have a lower abundance compared to the high-alpha stars. The low-alpha stars display the same abundance patterns of high {[}Ba/Y] and low {[}Y/Eu] as observed in present-day dwarf spheroidal galaxies, although with smaller abundance differences, when compared to the high-alpha stars. These distinct chemical patterns have been attributed to differences in the star formation rate between the two populations and the contribution of low-metallicity, low-mass asymptotic giant branch (AGB) stars to the low-alpha population. By comparing the low-alpha population with AGB stellar models, we place constraints on the mass range of the AGB stars. (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 |
| Modalidade de apoio: | 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 |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |