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        Estimation of Stellar Metal Abundance. II : A Recalibration of the Ca II K Technique, and the Autocorrelation Function Method

        Author
        Beers, T.C.
        Rossi, S.
        Norris, J.E.
        Ryan, Sean G.
        Shefler, T.
        Attention
        2299/2728
        Abstract
        We have recalibrated a method for the estimation of stellar metal abundance, parameterized as [Fe/H], based on medium-resolution (1–2 Å) optical spectra (the majority of which cover the wavelength range 3700–4500 Å). The equivalent width of the Ca II K line (3933 Å) as a function of [Fe/H] and broadband B-V color, as predicted from spectrum synthesis and model atmosphere calculations, is compared with observations of 551 stars with high-resolution abundances available from the literature (a sevenfold increase in the number of calibration stars that were previously available). A second method, based on the Fourier autocorrelation function technique first described by Ratnatunga & Freeman, is used to provide an independent estimate of [Fe/H], as calibrated by comparison with 405 standard-star abundances. Metallicities based on a combination of the two techniques for dwarfs and giants in the color range 0.30 ≤ (B-V)0 ≤ 1.2 exhibit an external 1 σ scatter of approximately 0.10–0.20 dex over the abundance range -4.0 ≤ [Fe/H] ≤ 0.5. Particular attention has been given to the determination of abundance estimates at the metal-rich end of the calibration, where our previous attempt suffered from a considerable zero-point offset. Radial velocities, accurate to approximately 10 km s-1, are reported for all 551 calibration stars.
        Publication date
        1999
        Published in
        The Astronomical Journal
        Published version
        https://doi.org/10.1086/300727
        Other links
        http://hdl.handle.net/2299/2728
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