Analysis and calibration of CaII triplet spectroscopy of red giant branch stars from VLT/FLAMES observations

Description

We demonstrate that low-resolution Ca II triplet (CaT) spectroscopic estimates of the overall metallicity ([Fe/H]) of individual red giant branch (RGB) stars in two nearby dwarf spheroidal galaxies (dSphs) agree to ±0.1-0.2 dex with detailed high-resolution spectroscopic determinations for the same stars over the range −2.5 < [Fe/H] < −0.5. For this study, we used a sample of 129 stars observed in low-and high-resolution modes with VLT/FLAMES in the Sculptor and Fornax dSphs. We also present the data-reduction steps we used in our low-resolution analysis and show that the typical accuracy of our velocity and CaT [Fe/H] measurement is ∼2 km s −1 and 0.1 dex, respectively. We conclude that CaT-[Fe/H] relations calibrated on globular clusters can be applied with confidence to RGB stars in composite stellar populations over the range −2.5 < [Fe/H] < −0.5.

Abstract

Monthly Notices of the Royal Astronomical Society, 383, pp. 183-199, http://dx.doi.org./10.1111/j.1365-2966.2007.12532.x

Abstract

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