2005PASP..117.1372C

We use an SX Phe period-luminosity relation to derive distance estimates and Galactic kinematic parameters for the short-period pulsating blue metal-poor stars CS 29499-057 and CS 22966-043. The resulting kinematics are quite distinctive relative to the metal-poor halo field. Even though these two field blue stragglers' binarity is consistent with the idea of formation in a mass transfer system, we speculate that these stars' origin instead lies in a Galactic merger or interaction with a dwarf galaxy satellite, or in the merger of a stellar binary system. The former possibility is consistent with CS 22966-043's significant [α/Fe] deficiency. A non-mass-transfer origin for both binaries is also consistent with (though not necessarily precluded by) the lack of any significant s-process enhancement seen in either star, and the long orbital period of CS 29499-057 that may preclude a mass transfer origin. In an effort to determine distances to additional blue metal-poor stars, we have photometrically monitored CS 22890-069, CS 22872-062, and CS 22884-065. However, the light curves of these three objects indicate no short-period photometric variability at the level of a few hundredths of a magnitude.