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The GALAH survey: An abundance, age, and kinematic inventory of the solar neighbourhood made with TGAS

Authors :
Buder, S.
Lind, K.
Ness, M. K.
Asplund, M.
Duong, L.
Lin, J.
Kos, J.
Casagrande, L.
Casey, A. R.
Bland-Hawthorn, J.
De Silva, G. M.
D'Orazi, V.
Freeman, K. C.
Martell, S. L.
Schlesinger, K. J.
Sharma, S.
Simpson, J. D.
Zucker, D. B.
Zwitter, T.
Cotar, K.
Dotter, A.
Hayden, M. R.
Hyde, E. A.
Kafle, P. R.
Lewis, G. F.
Nataf, D. M.
Nordlander, T.
Reid, W.
Rix, H. -W.
Skuladottir, A.
Stello, D.
Ting, Y. -S.
Traven, G.
Wyse, R. F. G.
Buder, S.
Lind, K.
Ness, M. K.
Asplund, M.
Duong, L.
Lin, J.
Kos, J.
Casagrande, L.
Casey, A. R.
Bland-Hawthorn, J.
De Silva, G. M.
D'Orazi, V.
Freeman, K. C.
Martell, S. L.
Schlesinger, K. J.
Sharma, S.
Simpson, J. D.
Zucker, D. B.
Zwitter, T.
Cotar, K.
Dotter, A.
Hayden, M. R.
Hyde, E. A.
Kafle, P. R.
Lewis, G. F.
Nataf, D. M.
Nordlander, T.
Reid, W.
Rix, H. -W.
Skuladottir, A.
Stello, D.
Ting, Y. -S.
Traven, G.
Wyse, R. F. G.
Publication Year :
2018

Abstract

The overlap between the spectroscopic Galactic Archaeology with HERMES (GALAH) survey & $Gaia$ provides a high-dimensional chemodynamical space of unprecedented size. We present a first analysis of a subset of this overlap, of 7066 dwarf, turn-off, & sub-giant stars. [...] We investigate correlations between chemical compositions, ages, & kinematics for this sample. Stellar parameters & elemental abundances are derived from the GALAH spectra with the spectral synthesis code SME. [...] We report Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, as well as Ba & we note that we employ non-LTE calculations for Li, O, Al, & Fe. We show that the use of astrometric & photometric data improves the accuracy of the derived spectroscopic parameters, especially $\log g$. [...] we recover the result that stars of the high-$\alpha$ sequence are typically older than stars in the low-$\alpha$ sequence, the latter spanning $-0.7<$[Fe/H]$<+0.5$. While these two sequences become indistinguishable in [$\alpha$/Fe] vs. [Fe/H] at the metal-rich regime, we find that age can be used to separate stars from the extended high-$\alpha$ & the low-$\alpha$ sequence even in this regime. [...] we find that the old stars ($>8$ Gyr have lower angular momenta $L_z$ than the Sun, which implies that they are on eccentric orbits & originate from the inner disk. Contrary to some previous smaller scale studies we find a continuous evolution in the high-$\alpha$-sequence up to super-solar [Fe/H] rather than a gap, which has been interpreted as a separate "high-$\alpha$ metal-rich" population. Stars in our sample that are younger than 10 Gyr, are mainly found on the low $\alpha$-sequence & show a gradient in $L_z$ from low [Fe/H] ($L_z>L_{z,\odot}$) towards higher [Fe/H] ($L_z<L_{z,\odot}$), which implies that the stars at the ends of this sequence are likely not originating from the close solar vicinity.<br />Comment: Revised paper resubmitted to A&A, 20 pages (+10 pages appendix), 25 figures, 2 tables, 1 catalog

Details

Database :
OAIster
Publication Type :
Electronic Resource
Accession number :
edsoai.on1363494343
Document Type :
Electronic Resource
Full Text :
https://doi.org/10.1051.0004-6361.201833218