  We present a theoretical analysis of the optical light curves (LCs) for
short-period high-mass transiting extrasolar planet systems. Our method
considers the primary transit, the secondary eclipse, and the overall phase
shape of the LC between the occultations. Phase variations arise from (i)
reflected and thermally emitted light by the planet, (ii) the ellipsoidal shape
of the star due to the gravitational pull of the planet, and (iii) the Doppler
shift of the stellar light as the star orbits the center of mass of the system.
Our full model of the out-of-eclipse variations contains information about the
planetary mass, orbital eccentricity, the orientation of periastron and the
planet's albedo. For a range of hypothetical systems we demonstrate that the
ellipsoidal variations (ii.) can be large enough to be distinguished from the
remaining components and that this effect can be used to constrain the planet's
mass. To detect the ellipsoidal variations, the LC requires a minimum precision
of 10-4, which coincides with the precision of the Kepler mission. As a test of
our approach, we consider the Kepler LC of the transiting object HAT-P-7. We
are able to estimate the mass of the companion, and confirm its planetary
nature solely from the LC data. Future space missions, such as PLATO and the
James Webb Space Telescope with even higher photometric precision, will be able
to reduce the errors in all parameters. Detailed modeling of any out-of-eclipse
variations seen in new systems will be a useful diagnostic tool prior to the
requisite ground based radial velocity follow-up.
