The GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm

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dc.contributor.authorHughes, Arvind C. N.
dc.contributor.authorSpitler, Lee R.
dc.contributor.authorZucker, Daniel B.
dc.contributor.authorNordlander, Thomas
dc.contributor.authorSimpson, Jeffrey
dc.contributor.authorDa Costa, Gary
dc.contributor.authorTing, Yuan-Sen
dc.contributor.authorLi, Chengyuan
dc.contributor.authorBland-Hawthorn, J.
dc.contributor.authorBuder, Sven
dc.contributor.authorCasey, Andrew
dc.contributor.authorDe Silva, Gayandhi M
dc.contributor.authorD'Orazi, Valentina
dc.contributor.authorFreeman, Kenneth
dc.contributor.authorHayden, Michael R.
dc.contributor.authorKos, Janez
dc.contributor.authorLewis, Geraint Francis
dc.contributor.authorlin, jane
dc.contributor.authorSchlesinger, Katharine
dc.date.accessioned2026-02-25T04:32:06Z
dc.date.available2026-02-25T04:32:06Z
dc.date.issued2022
dc.date.updated2023-10-01T07:16:00Z
dc.description.abstractExtremely metal-poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large sample of ∼600,000 high-resolution stellar spectra from the GALAH survey plus a machine-learning algorithm to find 54 candidates with estimated [Fe/H] ≤-3.0, six of which have [Fe/H] ≤-3.5. Our sample includes ∼20% main-sequence EMP candidates, unusually high for EMP star surveys. We find the magnitude-limited metallicity distribution function of our sample is consistent with previous work that used more complex selection criteria. The method we present has significant potential for application to the next generation of massive stellar spectroscopic surveys, which will expand the available spectroscopic data well into the millions of stars.
dc.description.sponsorshipParts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. L.S. acknowledges support from Australian Research Council Discovery Project DP190102448. D.B.Z., J.S., and S.L.M. acknowledge support from Australian Research Council Discovery Project DP180101791. Y.S.T. acknowledges support from the Australian Research Council through DECRA Fellowship DE220101520. This work was based on data acquired at the Anglo-Australian Telescope.
dc.format.mimetypeapplication/pdfen_AU
dc.identifier.issn0004637X
dc.identifier.urihttps://hdl.handle.net/1885/733806553
dc.language.isoen_AUen_AU
dc.provenanceOriginal content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI (https://creativecommons.org/licenses/by/4.0/).
dc.publisherAmerican Astronomical Society
dc.rights© 2022 The Author(s)
dc.rights.licenseCreative Commons Attribution 4.0 licence
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.sourceThe Astrophysical Journal
dc.titleThe GALAH Survey: A New Sample of Extremely Metal-poor Stars Using a Machine-learning Classification Algorithm
dc.typeJournal article
dcterms.accessRightsOpen Access
local.bibliographicCitation.issue1
local.contributor.affiliationHughes, Arvind C. N., Macquarie University
local.contributor.affiliationSpitler, Lee R., Macquarie University
local.contributor.affiliationZucker, Daniel B., Macquarie University
local.contributor.affiliationNordlander, Thomas, College of Science, ANU
local.contributor.affiliationSimpson, Jeffrey, UNSW
local.contributor.affiliationDa Costa, Gary, College of Science, ANU
local.contributor.affiliationTing, Yuan-Sen, College of Science, ANU
local.contributor.affiliationLi, Chengyuan , Sun Yat-sen University
local.contributor.affiliationBland-Hawthorn, J., The University of Sydney
local.contributor.affiliationBuder, Sven, College of Science, ANU
local.contributor.affiliationCasey, Andrew, Monash University
local.contributor.affiliationDe Silva, Gayandhi M, Macquarie University
local.contributor.affiliationD'Orazi, Valentina, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova
local.contributor.affiliationFreeman, Kenneth, College of Science, ANU
local.contributor.affiliationHayden, Michael R., University of Sydney
local.contributor.affiliationKos, Janez, Faculty of Mathematics and Physics, University of Ljubljana
local.contributor.affiliationLewis, Geraint Francis, University of Sydney
local.contributor.affiliationlin, jane, College of Science, ANU
local.contributor.affiliationSchlesinger, Katharine, College of Science, ANU
local.contributor.authoruidNordlander, Thomas, u1019177
local.contributor.authoruidDa Costa, Gary, u9501331
local.contributor.authoruidTing, Yuan-Sen, u5043815
local.contributor.authoruidBuder, Sven, u1054434
local.contributor.authoruidFreeman, Kenneth, u7000399
local.contributor.authoruidlin, jane, u5027368
local.contributor.authoruidSchlesinger, Katharine, u5239304
local.description.notesImported from ARIES
local.identifier.absfor510100 - Astronomical sciences
local.identifier.absseo280120 - Expanding knowledge in the physical sciences
local.identifier.ariespublicationa383154xPUB36486
local.identifier.citationvolume930
local.identifier.doi10.3847/1538-4357/ac5fa7
local.identifier.scopusID2-s2.0-85130181500
local.type.statusPublished Version

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