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arXiv · 1306.3883

The Near Infrared Ca II Triplet as Metallicity Indicator: II Extension to extremely metal-poor metallicity regimes

R. Carrera·E. Pancino·C. Gallart·A. del Pino
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Abstract

We extend our previous calibration of the infrared Ca II triplet as metallicity indicator to the metal-poor regime by including observations of 55 field stars with [Fe/H] down to -4.0 dex. While we previously solved the saturation at high-metallicity using a combination of a Lorentzian plus a Gaussian to reproduce the line profiles, in this paper we address the non-linearity at low-metallicity following the suggestion of Starkenburg et al 2010 of adding two non-linear terms to the relation among the [Fe/H], luminosity, and strength of the Calcium triplet lines. Our calibration thus extends from -4.0 to +0.5 in metallicity and is presented using four different luminosity indicators: V-V_{HB}, M_V, M_I, and M_K. The calibration obtained in this paper results in a tight correlation between [Fe/H] abundances measured from high resolution spectra and [Fe/H] values derived from the CaT, over the whole metallicity range covered.

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R. Carrera, E. Pancino, C. Gallart, A. del Pino. 2013-06-17. The Near Infrared Ca II Triplet as Metallicity Indicator: II Extension to extremely metal-poor metallicity regimes. https://doi.org/10.1093/mnras/stt1126

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