Metal Abundance Calibration of the Ca II Triplet Lines in RR Lyrae Stars

Abstract

The GAIA satellite is likely to observe thousands of RR Lyrae stars within a small spectral window, between 8470A and 8750A, at a resolution of 11,500. In order to derive the metallicity of RR Lyrae stars from Gaia, we have obtained numerous spectra of RR Lyrae stars at a resolution of 35,000 with the Apache Point Observatory 3.5 m echelle spectrograph. We have correlated the Ca II triplet line strengths with metallicity as derived from Fe II abundances, analogous to Preston's (1959) use of the Ca II K line to estimate the metallicity of RR Lyrae stars. The Ca II line at 8498A is the least blended with neighboring Paschen lines and thus provides the best correlation.

arXiv commentAccepted for publication in Astrophysics & Space Science

References in corpus (2)

• The Effects of Age on Red Giant Metallicities Derived from the Near-Infrared Ca II Triplet
• The Luminosities and Distance Scales of Type II Cepheid and RR Lyrae variables

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• On the Use of Field RR Lyrae as Galactic Probes. III. The $\alpha$-element abundances
• Chemical abundances in a high velocity RR Lyrae star near the bulge
• RR Lyrae stars as probes of the outer Galactic halo: Chemical and kinematic analysis of a pilot sample
• Metal-Poor Type II Cepheids with Periods Less Than Three Days
• An empirical metallicity tracer in CEMP and C-normal stars