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

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    K. Lind, Max Planck Inst Astron, Max Planck Society, Max Planck Inst Halbleiterlabor, Max Planck Society, Uppsala Univ, Uppsala University, Dept Phys & Astron, Uppsala Univ., Uppsala University Hospital, Uppsala, A. M. Amarsi, RSPAS, Australian National University, M. Asplund, RSPAS, Australian National University, P. S. Barklem, Uppsala University Hospital, Uppsala, M A M Bautista, Western Michigan University, M. Bergemann, Max Planck Inst Halbleiterlabor, Max Planck Society,
  • R. Collet
  • D. Kiselman, University of Stockholm, Stockholm, J. Leenaarts, University of Stockholm, Stockholm, T. M. D. Pereira, Oslo 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
Publication statusPublished - Jul 2017

    Research areas

  • 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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