The GALAH+ Survey : Third Data Release
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Author
Buder, Sven
Sharma, Sanjib
Kos, Janez
Amarsi, Anish M.
Nordlander, Thomas
Lind, Karin
Martell, Sarah L.
Asplund, Martin
Bland-Hawthorn, Joss
Casey, Andrew R.
Silva, Gayandhi M. De
D'Orazi, Valentina
Freeman, Ken C.
Hayden, Michael R.
Lewis, Geraint F.
Lin, Jane
Schlesinger, Katharine J.
Simpson, Jeffrey D.
Stello, Dennis
Zucker, Daniel B.
Zwitter, Tomaz
Beeson, Kevin L.
Buck, Tobias
Casagrande, Luca
Clark, Jake T.
Cotar, Klemen
Costa, Gary S. Da
Grijs, Richard de
Feuillet, Diane
Horner, Jonathan
Kafle, Prajwal R.
Khanna, Shourya
Kobayashi, Chiaki
Liu, Fan
Montet, Benjamin T.
Nandakumar, Govind
Nataf, David M.
Ness, Melissa K.
Spina, Lorenzo
Tepper-Garcia, Thor
Ting, Yuan-Sen
Traven, Gregor
Vogrincic, Rok
Wittenmyer, Robert A.
Wyse, Rosemary F. G.
Zerjal, Marusa
collaboration, the GALAH
Attention
2299/24528
Abstract
The ensemble of chemical element abundance measurements for stars, along with precision distances and orbit properties, provides high-dimensional data to study the evolution of the Milky Way. With this third data release of the Galactic Archaeology with HERMES (GALAH) survey, we publish 678 423 spectra for 588 571 mostly nearby stars (81.2% of stars are within 75 stellar clusters. We derive stellar parameters $T_\text{eff}$, $\log g$, [Fe/H], $v_\text{mic}$, $v_\text{broad}$ & $v_\text{rad}$ using our modified version of the spectrum synthesis code Spectroscopy Made Easy (SME) and 1D MARCS model atmospheres. We break spectroscopic degeneracies in our spectrum analysis with astrometry from $Gaia$ DR2 and photometry from 2MASS. We report abundance ratios [X/Fe] for 30 different elements (11 of which are based on non-LTE computations) covering five nucleosynthetic pathways. We describe validations for accuracy and precision, flagging of peculiar stars/measurements and recommendations for using our results. Our catalogue comprises 65% dwarfs, 34% giants, and 1% other/unclassified stars. Based on unflagged chemical composition and age, we find 62% young low-$\alpha$, 9% young high-$\alpha$, 27% old high-$\alpha$, and 2% stars with $\mathrm{[Fe/H]} \leq -1$. Based on kinematics, 4% are halo stars. Several Value-Added-Catalogues, including stellar ages and dynamics, updated after $Gaia$ eDR3, accompany this release and allow chrono-chemodynamic analyses, as we showcase.