Show simple item record

dc.contributor.authorAmarsi, A. M.
dc.contributor.authorLind, K.
dc.contributor.authorOsorio, Y.
dc.contributor.authorNordlander, T.
dc.contributor.authorBergemann, M.
dc.contributor.authorReggiani, H.
dc.contributor.authorWang, E. X.
dc.contributor.authorBuder, S.
dc.contributor.authorAsplund, M.
dc.contributor.authorBarklem, P. S.
dc.contributor.authorWehrhahn, A.
dc.contributor.authorSkúladóttir, Á.
dc.contributor.authorKobayashi, C.
dc.contributor.authorKarakas, A. I.
dc.contributor.authorGao, X. D.
dc.contributor.authorBland-Hawthorn, J.
dc.contributor.authorSilva, G. M. De
dc.contributor.authorKos, J.
dc.contributor.authorLewis, G. F.
dc.contributor.authorMartell, S. L.
dc.contributor.authorSharma, S.
dc.contributor.authorSimpson, J. D.
dc.contributor.authorZucker, D. B.
dc.contributor.authorČotar, K.
dc.contributor.authorHorner, J.
dc.contributor.authorcollaboration, the GALAH
dc.date.accessioned2020-10-09T00:10:46Z
dc.date.available2020-10-09T00:10:46Z
dc.date.issued2020-10-06
dc.identifier.citationAmarsi , A M , Lind , K , Osorio , Y , Nordlander , T , Bergemann , M , Reggiani , H , Wang , E X , Buder , S , Asplund , M , Barklem , P S , Wehrhahn , A , Skúladóttir , Á , Kobayashi , C , Karakas , A I , Gao , X D , Bland-Hawthorn , J , Silva , G M D , Kos , J , Lewis , G F , Martell , S L , Sharma , S , Simpson , J D , Zucker , D B , Čotar , K , Horner , J & collaboration , T GALAH 2020 , ' The GALAH Survey : Non-LTE departure coefficients for large spectroscopic surveys ' , Astronomy & Astrophysics , vol. 642 , A62 . https://doi.org/10.1051/0004-6361/202038650
dc.identifier.issn0004-6361
dc.identifier.otherArXiv: http://arxiv.org/abs/2008.09582v1
dc.identifier.otherORCID: /0000-0002-4343-0487/work/81741564
dc.identifier.urihttp://hdl.handle.net/2299/23226
dc.description19 pages, 25 figures, 2 tables, arXiv abstract abridged; accepted for publication in A&A
dc.description.abstractMassive sets of stellar spectroscopic observations are rapidly becoming available and these can be used to determine the chemical composition and evolution of the Galaxy with unprecedented precision. One of the major challenges in this endeavour involves constructing realistic models of stellar spectra with which to reliably determine stellar abundances. At present, large stellar surveys commonly use simplified models that assume that the stellar atmospheres are approximately in local thermodynamic equilibrium (LTE). To test and ultimately relax this assumption, we have performed non-LTE calculations for $13$ different elements (H, Li, C, N, O, Na, Mg, Al, Si, K, Ca, Mn, and Ba), using recent model atoms that have physically-motivated descriptions for the inelastic collisions with neutral hydrogen, across a grid of $3756$ 1D MARCS model atmospheres that spans $3000\leq T_{\mathrm{eff}}/\mathrm{K}\leq8000$, $-0.5\leq\log{g/\mathrm{cm\,s^{-2}}}\leq5.5$, and $-5\leq\mathrm{[Fe/H]}\leq1$. We present the grids of departure coefficients that have been implemented into the GALAH DR3 analysis pipeline in order to complement the extant non-LTE grid for iron. We also present a detailed line-by-line re-analysis of $50126$ stars from GALAH DR3. We found that relaxing LTE can change the abundances by between $-0.7\,\mathrm{dex}$ and $+0.2\,\mathrm{dex}$ for different lines and stars. Taking departures from LTE into account can reduce the dispersion in the $\mathrm{[A/Fe]}$ versus $\mathrm{[Fe/H]}$ plane by up to $0.1\,\mathrm{dex}$, and it can remove spurious differences between the dwarfs and giants by up to $0.2\,\mathrm{dex}$. The resulting abundance slopes can thus be qualitatively different in non-LTE, possibly with important implications for the chemical evolution of our Galaxy.en
dc.format.extent18
dc.format.extent6535223
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysics
dc.subjectastro-ph.SR
dc.subjectastro-ph.GA
dc.titleThe GALAH Survey : Non-LTE departure coefficients for large spectroscopic surveysen
dc.contributor.institutionCentre for Astrophysics Research
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionSchool of Physics, Engineering & Computer Science
dc.contributor.institutionDepartment of Physics, Astronomy and Mathematics
dc.description.statusPeer reviewed
rioxxterms.versionofrecord10.1051/0004-6361/202038650
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record