The Chemical Compositions of the SRd Variable Stars. I. XY Aquarii, RX Cephei, AB Leonis, and SV Ursae Majoris

Abstract

Chemical compositions are derived from high-resolution spectra for four stars classed as SRd variables in the General Catalogue of Variable Stars. Two stars—XY Aquarii and RX Cephei—are of solar metallicity and most likely not variable stars. Their spectroscopic effective temperatures and surface gravities correspond to the spectral types G0 V for XY Aqr and G8 III for RX Cep. Two stars are undisputed variables and shown here to be metal-poor supergiants: AB Leonis with [Fe/H] and SV Ursae Majoris with [Fe/H] . The metallicities and high radial velocities show them to be halo stars