THE ASTRONOMICAL JOURNAL    VOLUME 110, NUMBER 5, PAGE 2400       NOVEMBER 1995

      OBSERVATIONS AND ANALYSIS OF THE FIELD CONTACT BINARY V728 HERCULIS

                                 R. H. NELSON

 College of New Caledonia, 3330 22nd Avenue, Prince George, BC, Canada V2N 1P8
                       Electronic mail: nelson@cnc.bc.ca

                 E. F. MILONE, J. VanLEEUWEN, AND DIRK TERRELL

    Rothney Astrophysical Observatory, Department of Physics and Astronomy,
 University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
   Electronic mail: milone@acs.ucalgary.ca, vanleeuwen@bear.ras.ucalgary.ca,
                             terrell@astro.ufl.edu

                                 J. E. PENFOLD

    Department of Mathematics, Physics, and Engineering, Mt. Royal College,
               4825 Richard Road SW, Calgary, AB, Canada T3G 1R7
                    Electronic mail: penfold@mtroyal.ab.ca

                                  J. KALLRATH

   BASF-AG, ZX/ZC C13, D-67056 Ludwigshafen, Federal Republic of Germany and
       Astronomische Institute der Universitaet Bonn, Auf dem Huegel 71,
                   D-53121 Bonn, Federal Republic of Germany
                    Electronic mail: kallrath@zx.basf-ag.de


                                   ABSTRACT

    The W UMa system V728 Her has been observed photometrically in B, V,
    and I_C passbands at the RAO over five seasons and spectroscopically at
    DAO over three seasons to obtain radial velocities.  New times of
    minima are provided and a period analysis confirms previous
    ephemerides.  The light and radial velocity curves were analyzed with
    the latest University of Calgary enhancements to the Wilson-Devinney
    program and new solutions found.  The best model is that involving a
    contact system with convective atmospheres.  In probing the best
    solution possible, use was made of the enhanced reflection and
    second-order limb-darkening calculations available in the 1993 version
    of the WD program.  The mass ratio 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 Msun and 0.295 +/- 0.009 Msun and the
    radii are 1.784 +/- 0.015 Rsun and 0.867 +/- 0.054 Rsun, respectively.
    The determined temperature difference, T2 - T1 is 165 +/- 19 K, and the
    luminosities for components 1 and 2 are 5.5 +/- 0.5 Lsun and 1.4 +/-
    0.3 Lsun, respectively.