Non-LTE line formation of Fe in late-type stars - IV. Modelling of the solar centre-to-limb variation in 3D

Publication: Research - peer-reviewJournal article

DOI

  • K. Lind
    K. LindMax Planck Inst Astron, Max Planck SocietyMax Planck Inst Halbleiterlabor, Max Planck SocietyUppsala Univ, Uppsala University, Dept Phys & AstronUppsala Univ.Uppsala University Hospital, Uppsala
  • A. M. Amarsi
    A. M. AmarsiRSPAS, Australian National University
  • M. Asplund
    M. AsplundRSPAS, Australian National University
  • P. S. Barklem
    P. S. BarklemUppsala University Hospital, Uppsala
  • M A M Bautista
    M A M BautistaWestern Michigan University
  • M. Bergemann
    M. BergemannMax Planck Inst Halbleiterlabor, Max Planck Society
  • R. Collet
  • D. Kiselman
    D. KiselmanUniversity of Stockholm, Stockholm
  • J. Leenaarts
    J. LeenaartsUniversity of Stockholm, Stockholm
  • T. M. D. Pereira
    T. M. D. PereiraOslo University, Oslo University Hospital, Oslo

Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an extensive 463-level Fe atom with new photoionization cross-sections for Fe I and quantum mechanical calculations of collisional excitation and charge transfer with neutral hydrogen; the latter effectively remove a free parameter that has hampered all previous line formation studies of Fe in non-local thermodynamic equilibrium (NLTE). For the first time, we use realistic 3D NLTE calculations of Fe for a quantitative comparison to solar observations. We confront our theoretical line profiles with observations taken at different viewing angles across the solar disc with the Swedish 1-m Solar Telescope. We find that 3D modelling well reproduces the observed centre-to-limb behaviour of spectral lines overall, but highlight aspects that may require further work, especially cross-sections for inelastic collisions with electrons. Our inferred solar iron abundance is log(epsilon(Fe)) = 7.48 +/- 0.04 dex.

Original languageEnglish
JournalRoyal Astronomical Society. Monthly Notices
Volume468
Issue number4
Pages (from-to)4311-4322
Number of pages12
ISSN0035-8711
DOIs
StatePublished - Jul 2017

    Keywords

  • atomic data, line: formation, methods: numerical, methods: observational, Sun: abundances, Sun: atmosphere, RELATIVE OSCILLATOR-STRENGTHS, ATOMIC DATA, PRECISION-MEASUREMENT, I TRANSITIONS, STELLAR ATMOSPHERES, IRON ABUNDANCES, CROSS-SECTIONS, QUIET SUN, EXCITATION, SIMULATIONS

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