TY - JOUR
T1 - The temporal evolution of neutron-capture elements in the Galactic discs
AU - Spina, Lorenzo
AU - Meléndez, Jorge
AU - Karakas, Amanda I.
AU - dos Santos, Leonardo
AU - Bedell, Megan
AU - Asplund, Martin
AU - Ramírez, Ivan
AU - Yong, David
AU - Alves-Brito, Alan
AU - Bean, Jacob L.
AU - Dreizler, Stefan
N1 - Publisher Copyright:
© 2017 The Author(s).
PY - 2018
Y1 - 2018
N2 - Important insights into the formation and evolution of the Galactic disc(s) are contained in the chemical compositions of stars. We analysed high-resolution and high signal-to-noise HARPS spectra of 79 solar twin stars in order to obtain precise determinations of their atmospheric parameters, ages (σ ~ 0.4 Gyr) and chemical abundances (σ < 0.01 dex) of 12 neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd and Dy). This valuable data set allows us to study the [X/Fe]-age relations over a time interval of ~10 Gyr and among stars belonging to the thin and thick discs. These relations show that (i) the s-process has been the main channel of nucleosynthesis of n-capture elements during the evolution of the thin disc; (ii) the thick disc is rich in r-process elements which suggests that its formation has been rapid and intensive. In addition, the heavy (Ba, La, Ce) and light (Sr, Y, Zr) s-process elements revealed details on the dependence between the yields of AGB stars and the stellar mass or metallicity. Finally, we confirmed that both [Y/Mg] and [Y/Al] ratios can be employed as stellar clocks, allowing ages of solar twin stars to be estimated with an average precision of ~ 0.5 Gyr.
AB - Important insights into the formation and evolution of the Galactic disc(s) are contained in the chemical compositions of stars. We analysed high-resolution and high signal-to-noise HARPS spectra of 79 solar twin stars in order to obtain precise determinations of their atmospheric parameters, ages (σ ~ 0.4 Gyr) and chemical abundances (σ < 0.01 dex) of 12 neutron-capture elements (Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd and Dy). This valuable data set allows us to study the [X/Fe]-age relations over a time interval of ~10 Gyr and among stars belonging to the thin and thick discs. These relations show that (i) the s-process has been the main channel of nucleosynthesis of n-capture elements during the evolution of the thin disc; (ii) the thick disc is rich in r-process elements which suggests that its formation has been rapid and intensive. In addition, the heavy (Ba, La, Ce) and light (Sr, Y, Zr) s-process elements revealed details on the dependence between the yields of AGB stars and the stellar mass or metallicity. Finally, we confirmed that both [Y/Mg] and [Y/Al] ratios can be employed as stellar clocks, allowing ages of solar twin stars to be estimated with an average precision of ~ 0.5 Gyr.
KW - Galaxy: abundances
KW - Galaxy: disc
KW - Galaxy: evolution
KW - Stars: abundances
UR - http://www.scopus.com/inward/record.url?scp=85042604193&partnerID=8YFLogxK
U2 - 10.1093/mnras/stx2938
DO - 10.1093/mnras/stx2938
M3 - Article
SN - 0035-8711
VL - 474
SP - 2580
EP - 2593
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -