학술논문
The GALAH survey: An abundance, age, and kinematic inventory of the solar neighbourhood made with TGAS
Document Type
Working Paper
Author
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.
Source
A&A 624, A19 (2019)
Subject
Language
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 Comment: Revised paper resubmitted to A&A, 20 pages (+10 pages appendix), 25 figures, 2 tables, 1 catalog