| Full text | |
| Author(s): |
Fishlock, C. K.
;
Yong, D.
;
Karakas, A. I.
;
Alves-Brito, A.
;
Melendez, J.
;
Nissen, P. E.
;
Kobayashi, C.
;
Casey, A. R.
Total Authors: 8
|
| Document type: | Journal article |
| Source: | Monthly Notices of the Royal Astronomical Society; v. 466, n. 4, p. 4672-4682, MAY 2017. |
| Web of Science Citations: | 8 |
| Abstract | |
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) | |
| FAPESP's process: | 12/24392-2 - High precision spectroscopy: impact in the study of planets, stars, the galaxy and cosmology |
| Grantee: | Jorge Luis Melendez Moreno |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 14/18100-4 - Stellar populations in the Milky Way: bulge, halo, disk and star forming regions; instrumentation for high resolution spectroscopy |
| Grantee: | Beatriz Leonor Silveira Barbuy |
| Support Opportunities: | Research Projects - Thematic Grants |