A type of pulsating variable that closely resembles a Delta Scuti star; abbr. SXPHE. These stars are subdwarfs and appear to belong to the spherical and older disk components of the Galaxy (Population II), as well as being present in globular clusters. They are metal-poor, whereas Delta Scuti stars are of Population I and hence metal-rich. The spectra are A2–F5, and multiple periods are present (range 0.04–0.08 days), with variable amplitudes up to 0.7 mag. SX Phoenicis itself varies between magnitudes 6.8 and 7.5 every 0.055 days (1.32 h).