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

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

doi:10.1051/0004-6361/201833218

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

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

S. Buder, K. Lind, M. K. Ness, M. Asplund, L. Duong, J. Lin, J. Kos, L. Casagrande, A. R. Casey, J. Bland-Hawthorn, …

Astronomy and astrophysics (Berlin), Vol.624, p.A19

04/01/2019

DOI: 10.1051/0004-6361/201833218

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Abstract

The overlap between the spectroscopic Galactic Archaeology with HERMES (GALAH) survey and 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, and subgiant stars. These stars have spectra from the GALAH survey and high parallax precision from the Gaia DR1 Tycho-Gaia Astrometric Solution. We investigate correlations between chemical compositions, ages, and kinematics for this sample. Stellar parameters and elemental abundances are derived from the GALAH spectra with the spectral synthesis code SPECTROSCOPY MADE EASY. We determine kinematics and dynamics, including action angles, from the Gaia astrometry and GALAH radial velocities. Stellar masses and ages are determined with Bayesian isochrone matching, using our derived stellar parameters and absolute magnitudes. We report measurements of Li, C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, as well as Ba and we note that we have employed non-LTE calculations for Li, O, Al, and Fe. We show that the use of astrometric and photometric data improves the accuracy of the derived spectroscopic parameters, especially log g. Focusing our investigation on the correlations between stellar age, iron abundance [Fe/H], and mean alpha-enhancement [alpha/Fe] of the magnitude-selected sample, we recover the result that stars of the high-a sequence are typically older than stars in the low-a sequence, the latter spanning iron abundances of -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-a and the low-a sequence even in this regime. When dissecting the sample by stellar age, 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 and originate from the inner disc. 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 and show a gradient in L-z from low [Fe/H] > (L-z > L-z,L-circle dot) towards higher [Fe/H] (L-z < L-z,L-circle dot), which implies that the stars at the ends of this sequence are likely not originating from the close solar vicinity.

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Title: Subtitle: The GALAH survey: An abundance, age, and kinematic inventory of the solar neighbourhood made with TGAS
Creators: S. Buder - Max Planck Institute for Astronomy
K. Lind - Max Planck Institute for Astronomy
M. K. Ness - Flatiron Health
M. Asplund - Mount Stromlo Observatory
L. Duong - Australian National University
J. Lin - Australian National University
J. Kos - University of Sydney
L. Casagrande - Mount Stromlo Observatory
A. R. Casey - Monash University
J. Bland-Hawthorn - ASTRO-3D
G. M. De Silva - University of Sydney
V D’Orazi - Osservatorio Astronomico di Padova
K. C. Freeman - Australian National University
S. L. Martell - UNSW Sydney
K. J. Schlesinger - Australian National University
S. Sharma - University of Sydney
J. D. Simpson - UNSW Sydney
D. B. Zucker - Macquarie University
T. Zwitter - University of Ljubljana
K. Cotar - University of Ljubljana
A. Dotter - Center for Astrophysics Harvard & Smithsonian
M. R. Hayden - University of Sydney
E. A. Hyde - Western Sydney University
P. R. Kafle - University of Western Australia
G. F. Lewis - University of Ljubljana
D. M. Nataf - Johns Hopkins University
T. Nordlander - Mount Stromlo Observatory
W. Reid - Macquarie University
H-W Rix - Max Planck Institute for Astronomy
A. Skuladottir - Max Planck Institute for Astronomy
D. Stello - UNSW Sydney
Y-S Ting - Princeton University
G. Traven - University of Ljubljana
R. F. G. Wyse - Johns Hopkins University
GALAH Collaboration
Resource Type: Journal article
Publication Details: Astronomy and astrophysics (Berlin), Vol.624, p.A19
Publisher: Edp Sciences S A
DOI: 10.1051/0004-6361/201833218
ISSN: 0004-6361
eISSN: 1432-0746
Number of pages: 30
Grant note: Zonta International District 24 2015-00415_3 / Swedish Research Council National Aeronautics and Space Administration; National Aeronautics & Space Administration (NASA) Alexander von Humboldt Foundation DP160103747 / ARC; Australian Research Council INCA 600398 / Marie Sklodowska Curie Actions; Marie Curie Actions FT160100402 / ARC Future Fellowship; Australian Research Council Allan C. and Dorothy H. Davis Fellowship A/2013B/13; A/2014A/25; A/2015A/19; A2017A/18 / Australian Astronomical Observatory Hunstead Fund for Astrophysics at the University of Sydney
Language: English
Date published: 04/01/2019
Academic Unit: Physics and Astronomy
Record Identifier: 9984701826902771

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