Radial velocity studies of close binary stars. VIII

Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the seventh set of 10 close binary systems: V410 Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD 93917, and NSV 223. All systems but three ( V523 Cas, HD 93917, NSV 223) were discovered photometrically by the Hipparcos mission. All systems are double-lined (SB2) binaries, and all but the detached, very close system V1130 Tau are contact binaries. The broadening function permitted improvement of the orbital elements for V523 Cas, which was the only system observed before for radial velocity variations. Spectroscopic/visual companions were detected for V410 Aur and HX UMa. Several of the studied systems are prime candidates for combined light and radial velocity synthesis solutions.