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The benchmark halo giant HD 122563: CNO abundances revisited with three-dimensional hydrodynamic model stellar atmospheres

Collet, Remo; Nordlund, A; Asplund, Martin; Hayek, W; Trampedach, Regner

Description

We present an abundance analysis of the low-metallicity benchmark red giant star HD 122563 based on realistic, state-of-the-art, high-resolution, three-dimensional (3D) model stellar atmospheres including non-grey radiative transfer through opacity binning with 4, 12, and 48 bins. The 48-bin 3D simulation reaches temperatures lower by similar to 300-500 K than the corresponding 1D model in the upper atmosphere. Small variations in the opacity binning, adopted line opacities, or chemical mixture...[Show more]

dc.contributor.authorCollet, Remo
dc.contributor.authorNordlund, A
dc.contributor.authorAsplund, Martin
dc.contributor.authorHayek, W
dc.contributor.authorTrampedach, Regner
dc.date.accessioned2020-04-16T23:47:37Z
dc.date.available2020-04-16T23:47:37Z
dc.identifier.issn0035-8711
dc.identifier.urihttp://hdl.handle.net/1885/203219
dc.description.abstractWe present an abundance analysis of the low-metallicity benchmark red giant star HD 122563 based on realistic, state-of-the-art, high-resolution, three-dimensional (3D) model stellar atmospheres including non-grey radiative transfer through opacity binning with 4, 12, and 48 bins. The 48-bin 3D simulation reaches temperatures lower by similar to 300-500 K than the corresponding 1D model in the upper atmosphere. Small variations in the opacity binning, adopted line opacities, or chemical mixture can cool the photospheric layers by a further similar to 100-300 K and alter the effective temperature by similar to 100 K. A 3D local thermodynamic equilibrium (LTE) spectroscopic analysis of Fe (I) and Fe (II) lines gives discrepant results in terms of derived Fe abundance, which we ascribe to non-LTE effects and systematic errors on the stellar parameters. We also determine C, N, and 0 abundances by simultaneously fitting CH, OH, NH, and CN molecular bands and lines in the ultraviolet, visible, and infrared. We find a small positive 3D-1D abundance correction for carbon (+0.03 dex) and negative ones for nitrogen (-0.07 dex) and oxygen (-0.34 dex). From the analysis of the [O-I] line at 6300.3 angstrom, we derive a significantly higher oxygen abundance than from molecular lines (+0.46 dex in 3D and +0.15 dex in ID). We rule out important OH photodissociation effects as possible explanation for the discrepancy and note that lowering the surface gravity would reduce the oxygen abundance difference between molecular and atomic indicators.
dc.description.sponsorshipRC acknowledges partial support from the Australian Research Council (ARC) through a Discovery Early Career Researcher Award grant (project DE120102940). Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant DNRF106). MA gratefully acknowledges funding through ARC Laureate Fellowship FL110100012. RT acknowledges funding from NASA grant NNX15AB24G.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherOxford University Press
dc.rights© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
dc.sourceMonthly Notices of the Royal Astronomical Society
dc.titleThe benchmark halo giant HD 122563: CNO abundances revisited with three-dimensional hydrodynamic model stellar atmospheres
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume475
dc.date.issued2018
local.identifier.absfor020110 - Stellar Astronomy and Planetary Systems
local.identifier.absfor020201 - Atomic and Molecular Physics
local.identifier.ariespublicationu4485658xPUB2135
local.publisher.urlhttps://academic.oup.com/journals/
local.type.statusPublished Version
local.contributor.affiliationCollet, Remo, College of Science, ANU
local.contributor.affiliationNordlund, A, University of Copenhagen
local.contributor.affiliationAsplund, Martin, College of Science, ANU
local.contributor.affiliationHayek, W, National Institute of Water and Atmospheric Research
local.contributor.affiliationTrampedach, Regner, University of Colorado
dc.relationhttp://purl.org/au-research/grants/arc/DE120102940
dc.relationhttp://purl.org/au-research/grants/arc/FL110100012
local.bibliographicCitation.issue3
local.bibliographicCitation.startpage3369
local.bibliographicCitation.lastpage3392
local.identifier.doi10.1093/mnras/sty002
local.identifier.absseo970102 - Expanding Knowledge in the Physical Sciences
dc.date.updated2019-11-25T07:53:17Z
local.identifier.thomsonID000427141900037
dcterms.accessRightsOpen Access
dc.provenancehttp://sherpa.ac.uk/romeo/issn/0035-8711/..."author can archive publisher's version/PDF" from Sherpa/Romeo (as at 17/04/2020). This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
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