The GALAH Survey: Second Data Release

By S. Buder, Martin Asplund, L. Duong, J. Kos, K. Lind, M. Ness, S. Sharma, J. Bland-Hawthorn, A. Casey, G. D. Silva and 56 more. 2018

254 citations recorded by the source corpus.

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 (T eff , logg, [Fe/H], [X/Fe], v mic , vsin i, AK S ) 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.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/0dfed5b96346ccbaa8aceaac5a74dba89f006d72

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Citations in the corpus

Neutron Star Mergers Might Not Be the Only Source of r-process Elements in the Milky Way (2018, background): “This data behaves similar to the chemical evolution of [α/Fe] (see e.g., Bensby et al. 2014; Buder et al. 2018; Spina et al. 2018).”
Abundance Estimates for 16 Elements in 6 Million Stars from LAMOST DR5 Low-Resolution Spectra (2019, background): “…recommended; 1 = ‘Line strength below 2σ = upper limit’; 2 = ‘The Cannon starts to extrapolate’; 3 = 1 + 2, both 1 and 2 raised; 4 = The χ2 of the best fitting model spectrum is significantly higher; 5 = 1 + 4, both 1 and 4 raised, similarly for 6 and 7 (see more details in Buder et al. 2018).”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, methodology): “These new observations, which provide improved calibrations of stellar masses and gravities, were reduced with the same pipeline as DR2 (Kos et al. 2017).”
The Revised TESS Input Catalog and Candidate Target List (2019, unknown): “…PASTEL L 93 k 2 Soubiran et al. (2016) Gaia-ESO DR3 29 k 3 Gilmore et al. (2012) TESS-HERMES DR1 25 k 4 Sharma et al. (2018) GALAH DR2 340 k 5 Buder et al. (2018) APOGEE-2 DR14 277 k 6 Abolfathi et al. (2018) LAMOST DR4 2.9M 7 Luo et al. (2015) RAVE DR5 484 k 8 Kunder et al. (2017)…”
The biggest splash (2019, background): “…et al. 2006) DR5 (Kunder et al. 2017), Gaia-ESO DR3 (Gilmore et al. 2012), GALAH (GALactic Archaeology with HERMES, De Silva et al. 2015; Martell et al. 2017) DR2 (Buder et al. 2018), and SEGUE (Sloan Extension for Galactic Understanding and Exploration, Yanny et al. 2009) surveys is included.”