The GALAH Survey: Second data release

the GALAH collaboration

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of theMilkyWay, 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, logg, [Fe/H], [X/Fe], vmic, vsin i, 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.

Original languageEnglish
Pages (from-to)4513-4552
Number of pages40
JournalMonthly Notices of the Royal Astronomical Society
Volume478
Issue number4
DOIs
Publication statusPublished - 21 Aug 2018

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archaeology
stars
guns (ordnance)
stellar atmospheres
open clusters
local thermodynamic equilibrium
data reduction
star clusters
synthesis
globular clusters
catalogs
line spectra
confidence
education
kinematics
physics
thermodynamics
spectroscopy
atmosphere
estimates

Cite this

the GALAH collaboration. / The GALAH Survey : Second data release. In: Monthly Notices of the Royal Astronomical Society. 2018 ; Vol. 478, No. 4. pp. 4513-4552.
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title = "The GALAH Survey: Second data release",
abstract = "The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of theMilkyWay, 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, logg, [Fe/H], [X/Fe], vmic, vsin i, 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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author = "{the GALAH collaboration} and Sven Buder and Martin Asplund and Ly Duong and Janez Kos and Karin Lind and Ness, {Melissa K.} and Sanjib Sharma and Joss Bland-Hawthorn and Casey, {Andrew R.} and {De Silva}, {Gayandhi M.} and Valentina D'Orazi and Freeman, {Ken C.} and Lewis, {Geraint F.} and Jane Lin and Martell, {Sarah L.} and Schlesinger, {Katharine J.} and Simpson, {Jeffrey D.} and Zucker, {Daniel B.} and Tomaž Zwitter and Amarsi, {Anish M.} and Borja Anguiano and Daniela Carollo and Luca Casagrande and Klemen Čotar and Cottrell, {Peter L.} and Costa, {Gary Da} and Gao, {Xudong D.} and Hayden, {Michael R.} and Jonathan Horner and Ireland, {Michael J.} and Kafle, {Prajwal R.} and Ulisse Munari and Nataf, {David M.} and Thomas Nordlander and Dennis Stello and Ting, {Yuan Sen} and Gregor Traven and Fred Watson and Wittenmyer, {Robert A.} and Wyse, {Rosemary F.G.} and David Yong and Zinn, {Joel C.} and Maruša Žerjal",
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The GALAH Survey : Second data release. / the GALAH collaboration.

In: Monthly Notices of the Royal Astronomical Society, Vol. 478, No. 4, 21.08.2018, p. 4513-4552.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The GALAH Survey

T2 - Second data release

AU - the GALAH collaboration

AU - Buder, Sven

AU - Asplund, Martin

AU - Duong, Ly

AU - Kos, Janez

AU - Lind, Karin

AU - Ness, Melissa K.

AU - Sharma, Sanjib

AU - Bland-Hawthorn, Joss

AU - Casey, Andrew R.

AU - De Silva, Gayandhi M.

AU - D'Orazi, Valentina

AU - Freeman, Ken C.

AU - Lewis, Geraint F.

AU - Lin, Jane

AU - Martell, Sarah L.

AU - Schlesinger, Katharine J.

AU - Simpson, Jeffrey D.

AU - Zucker, Daniel B.

AU - Zwitter, Tomaž

AU - Amarsi, Anish M.

AU - Anguiano, Borja

AU - Carollo, Daniela

AU - Casagrande, Luca

AU - Čotar, Klemen

AU - Cottrell, Peter L.

AU - Costa, Gary Da

AU - Gao, Xudong D.

AU - Hayden, Michael R.

AU - Horner, Jonathan

AU - Ireland, Michael J.

AU - Kafle, Prajwal R.

AU - Munari, Ulisse

AU - Nataf, David M.

AU - Nordlander, Thomas

AU - Stello, Dennis

AU - Ting, Yuan Sen

AU - Traven, Gregor

AU - Watson, Fred

AU - Wittenmyer, Robert A.

AU - Wyse, Rosemary F.G.

AU - Yong, David

AU - Zinn, Joel C.

AU - Žerjal, Maruša

PY - 2018/8/21

Y1 - 2018/8/21

N2 - The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of theMilkyWay, 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, logg, [Fe/H], [X/Fe], vmic, vsin i, 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.

AB - The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of theMilkyWay, 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, logg, [Fe/H], [X/Fe], vmic, vsin i, 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.

KW - Methods: data analysis

KW - Methods: observational

KW - Stars: abundances

KW - Stars: fundamental parameters

KW - Surveys

KW - The Galaxy

UR - http://www.scopus.com/inward/record.url?scp=85050813726&partnerID=8YFLogxK

U2 - 10.1093/mnras/sty1281

DO - 10.1093/mnras/sty1281

M3 - Article

VL - 478

SP - 4513

EP - 4552

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 4

ER -