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

作者：Battaglia G^*; Irwin M; Tolstoy E; Hill V; Helmi A; Letarte B; Jablonka P

来源：Monthly Notices of the Royal Astronomical Society, 2008, 383(1): 183-199.

DOI：10.1111/j.1365-2966.2007.12532.x

• techniques : spectroscopic
• stars : abundances
• galaxies : dwarf
• galaxies : star clusters

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 similar to 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.

• 出版日期2008-1-1