TY - JOUR
T1 - Estimation of Stellar Metal Abundance. II
T2 - A Recalibration of the Ca II K Technique, and the Autocorrelation Function Method
AU - Beers, T.C.
AU - Rossi, S.
AU - Norris, J.E.
AU - Ryan, Sean G.
AU - Shefler, T.
N1 - Original article can be found at: http://www.iop.org/EJ/journal/aj Copyright American Astronomical Society DOI: 10.1086/300727 [Full text of this article is not available in the UHRA]
PY - 1999
Y1 - 1999
N2 - 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.
AB - 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.
U2 - 10.1086/300727
DO - 10.1086/300727
M3 - Article
SN - 0004-6256
VL - 117
SP - 981
EP - 1009
JO - The Astronomical Journal
JF - The Astronomical Journal
ER -