The GALAH survey: second data release

Buder, Sven and Asplund, Martin and Duong, Ly and Kos, Janez and Lind, Karin and Ness, Melissa K. and Sharma, Sanjib and Bland-Hawthorn, Joss and Casey, Andrew R. and de Silva, Gayandhi M. and D'Orazi, Valentina and Freeman, Ken C. and Lewis, Geraint F. and Lin, Jane and Martell, Sarah L. and Schlesinger, Katharine J. and Simpson, Jeffrey D. and Zucker, Daniel B. and Zwitter, Tomaz and Amarsi, Anish M. and Anguiano, Borja and Carollo, Daniela and Casagrande, Luca and Cotar, Klemen and Cottrell, Peter L. and Da Costa, Gary and Gao, Xudong D. and Hayden, Michael R. and Horner, Jonathan and Ireland, Michael J. and Kafle, Prajwal R. and Munari, Ulisse and Nataf, David M. and Nordlander, Thomas and Stello, Dennis and Ting, Yuan-Sen and Traven, Gregor and Watson, Fred and Wittenmyer, Robert A. and Wyse, Rosemary F. G. and Yong, David and Zinn, Joel C. and Zerjal, Marusa (2018) The GALAH survey: second data release. Monthly Notices of the Royal Astronomical Society, 478 (4). pp. 4513-4552. ISSN 0035-8711

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The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of the Milky Way, designed to deliver complementary chemical information to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342 682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community. Here we present the target selection, observation, data reduction, and detailed explanation of how the spectra were analysed to estimate stellar parameters and element abundances. For the stellar analysis, we have used a multistep approach. We use the physics-driven spectrum synthesis of Spectroscopy Made Easy (SME) to derive stellar labels (Teff, log g, [Fe/H], [X/Fe], vmic, vsin i, A K S AKS⁠) for a representative training set of stars. This information is then propagated to the whole sample with the data-driven method of The Cannon. Special care has been exercised in the spectral synthesis to only consider spectral lines that have reliable atomic input data and are little affected by blending lines. Departures from local thermodynamic equilibrium (LTE) are considered for several key elements, including Li, O, Na, Mg, Al, Si, and Fe, using 1D marcs stellar atmosphere models. Validation tests including repeat observations, Gaia benchmark stars, open and globular clusters, and K2 asteroseismic targets lend confidence to our methods and results. Combining the GALAH DR2 catalogue with the kinematic information from Gaia will enable a wide range of Galactic Archaeology studies, with unprecedented detail, dimensionality, and scope.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences (1 Jul 2013 - 5 Sep 2019)
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences (1 Jul 2013 - 5 Sep 2019)
Date Deposited: 13 Mar 2019 03:13
Last Modified: 10 Sep 2019 05:40
Uncontrolled Keywords: surveys; galaxies; data analysis; fundamental parameters; stars
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
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