The GALAH survey: temporal chemical enrichment of the galactic disc
Article
Article Title | The GALAH survey: temporal chemical enrichment of the galactic disc |
---|---|
ERA Journal ID | 1074 |
Article Category | Article |
Authors | Lin, Jane (Author), Asplund, Martin (Author), Ting, Yuan-Sen (Author), Casagrande, Luca (Author), Buder, Sven (Author), Bland-Hawthorn, Joss (Author), Casey, Andrew R. (Author), de Silva, Gayandhi M. (Author), D'Orazi, Valentina (Author), Freeman, Ken C. (Author), Kos, Janez (Author), Lind, K. (Author), Martell, Sarah L. (Author), Sharma, Sanjib (Author), Simpson, Jeffrey D. (Author), Zwitter, Tomaz (Author), Zucker, Daniel B. (Author), Minchev, Ivan (Author), Cotar, Klemen (Author), Hayden, Michael (Author), Horner, Jonti (Author), Lewis, Geraint F. (Author), Nordlander, Thomas (Author), Wyse, Rosemary F.G. (Author) and Zerjal, Marusa (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 491 (2), pp. 2043-2056 |
Number of Pages | 14 |
Year | 2020 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stz3048 |
Web Address (URL) | https://academic.oup.com/mnras/article/491/2/2043/5622880 |
Abstract | We present isochrone ages and initial bulk metallicities ([Fe/H]_{bulk}, by accounting for diffusion) of 163 722 stars from the GALAH Data Release 2, mainly composed of main-sequence turn-off stars and subgiants (7000 K> T_{ eff}> 4000 K and log g>3 dex). The local age- metallicity relationship (AMR) is nearly flat but with significant scatter at all ages; the scatter is even higher when considering the observed surface abundances. After correcting for selection effects, the AMR appears to have intrinsic structures indicative of two star formation events, which we speculate are connected to the thin and thick discs in the solar neighbourhood. We also present abundance ratio trends for 16 elements as a function of age, across different [Fe/H]_{bulk} bins. In general, we find the trends in terms of [X/Fe] versus age from our far larger sample to be compatible with studies based on small (∼100 stars) samples of solar twins, but we now extend them to both sub- and supersolar metallicities. The α-elements show differing behaviour: the hydrostatic α-elements O and Mg show a steady decline with time for all metallicities, while the explosive α-elements Si, Ca, and Ti are nearly constant during the thin-disc epoch (ages ≲ 12 Gyr). The s-process elements Y and Ba show increasing [X/Fe] with time while the r-process element Eu has the opposite trend, thus favouring a primary production from sources with a short time delay such as core-collapse supernovae over long-delay events such as neutron star mergers. |
Keywords | stars: abundances; stars: fundamental parameters; solar; neighbourhood; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Institution of Origin | University of Southern Queensland |
Byline Affiliations | Australian National University |
Institute for Advanced Study, United States | |
Max Planck Society, Germany | |
University of Sydney | |
Monash University | |
Macquarie University | |
National Institute for Astrophysics, Italy | |
University of Ljubljana, Slovenia | |
University of New South Wales | |
Leibniz Institute for Astrophysics, Germany | |
Centre for Astrophysics | |
Johns Hopkins University, United States |
https://research.usq.edu.au/item/q5x13/the-galah-survey-temporal-chemical-enrichment-of-the-galactic-disc
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