Both accurate and precise gf-values for Fe II lines

J. Meléndez, B. Barbuy

Abstract
We present a new set of oscillator strengths for 142 Fe ii lines in the wavelength range 4000–8000 Å. Our gf -values are both accurate and precise, because each multiplet was globally normalized using laboratory data (accuracy), while the relative gf -values of individual lines within a given multiplet were obtained from theoretical calculations (precision). Our line list was tested with the Sun and high-resolution (R ≈ 105), high-S/N (≈700–900) Keck+HIRES spectra of the metal-poor stars HD 148816 and HD 140283, for which line-to-line scatter (σ) in the iron abundances from Fe ii lines as low as 0.03, 0.04, and 0.05 dex are found, respectively. For these three stars the standard error in the mean iron abundance from Fe_ii lines is negligible (σ_mean ≤ 0.01 dex). The mean solar iron abundance obtained using our gf -values and different model atmospheres is A_Fe = 7.45(σ = 0.02).

Keywords
Sun: abundances – Sun: photosphere – stars: abundances – atomic data

Notes
Based in part on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration.

Astronomy and Astrophysics
Volume 497, Page 611
April 2009

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