OBSERVATIONS AND ANALYSIS OF THE FIELD CONTACT BINARY V728 HERCULIS

The W UMa system V728 Her has been observed photometrically in B, V, a nd I-C passbands at the RAO over five seasons and spectroscopically at DAO over three seasons to obtain radial velocities. New times of mini ma are provided and a period analysis confirms previous ephemerides. T he light and radial velocity curves were analyzed with the latest Univ ersity of Calgary enhancements to the Wilson-Devinney program and new solutions found. The best model is that involving a contact system wit h convective atmospheres. In probing the best solution possible, use w as made of the enhanced reflection and second-order limb-darkening cal culations available in the 1993 version of the WD program. The mass ra tio is found to be 0.1786+/-0.0023. The contact parameter is found to be f=0.71+/-0.11. The masses are determined to be 1.654+/-0.037 M. and 0.295+/-0.009 M. and the radii are 1.784+/-0.015 R. and 0.867+/-0.054 R., respectively. The determined temperature difference, T-2-T-1 is 1 65+/-19 K, and the luminosities for components 1 and 2 are 5.5+/-0.5 L . and 1.4+/-0.3 respectively. (C) 1995 American Astronomical Society.