unveiling systematic biases in the 1d lte excitation-ionization balance of fe for fgk stars: A novel approach to determination of stellar parameters

Gregory R. Ruchti*, Maria Bergemann, Aldo Serenelli, Luca Casagrande, Karin Lind

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    51 Citations (Scopus)

    Abstract

    We present a comprehensive analysis of different techniques available for the spectroscopic analysis of FGK stars and provide a recommended methodology which efficiently estimates accurate stellar atmospheric parameters for large samples of stars. Our analysis includes a simultaneous equivalent width analysis of Fe I and Fe II spectral lines, and for the first time, utilizes on-the-fly non-local thermodynamic equilibrium (NLTE) corrections of individual Fe I lines. We further investigate several temperature scales, finding that estimates from Balmer line measurements provide the most accurate effective temperatures at all metallicities. We apply our analysis to a large sample of both dwarf and giant stars selected from the Radial Velocity Experiment (RAVE) survey. We then show that the difference between parameters determined by our method and that by the standard 1D LTE excitation-ionization balance of Fe reveals substantial systematic biases: up to 400 K in effective temperature, 1.0 dex in surface gravity and 0.4 dex in metallicity for stars with [Fe/H] -2.5. This has large implications for the study of the stellar populations in the Milky Way

    Original languageEnglish
    Pages (from-to)126-134
    Number of pages9
    JournalMonthly Notices of the Royal Astronomical Society
    Volume429
    Issue number1
    DOIs
    Publication statusPublished - 11 Feb 2013

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