Metallicities from high-resolution spectra of 49 RR Lyrae variables

Abstract

Accurate metallicities of RR Lyrae are extremely important in constraining period-luminosity-metallicity (PLZ) relationships, particularly in the near-infrared. We analyse 69 high-resolution spectra of Galactic RR Lyrae stars from the Southern African Large Telescope. We measure metallicities of 58 of these RR Lyrae stars with typical uncertainties of 0.15 dex. All but one RR Lyrae in this sample has accurate ($\sigma -{\varpi }\lesssim 10{{\ \rm per\ cent}}$) parallax from Gaia. Combining these new high-resolution spectroscopic abundances with similar determinations from the literature for 93 stars, we present new PLZ relationships in WISE W1 and W2 magnitudes, and the Wesenheit magnitudes W(W1, V - W1) and W(W2, V - W2).