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Ellipsoidal variables present light-curve modulations caused by stellardistortion, induced by tidal interaction with their companions. An analyticalapproximated model of the ellipsoidal modulation is given as a discrete Fourierseries by Morris and Naftilan 1993 (MN93). Based on numerical simulations usingthe PHOEBE code we present here updated amplitudes of the first three harmonicsof the model. The expected amplitudes are given as a function of the mass ratioand inclination of the binary system and the fillout factor of theprimary---the ratio between the stellar radius and that of its Roche lobe. Thecorrections can get up to 30% relative to the MN93 model for fillout factorsclose to unity. The updated model can be instrumental in searching forshort-period binaries with compact-object secondaries in large data sets ofphotometric light curves. As shown in one OGLE light-curve example, the minimummass ratio can be obtained by using only the amplitudes of the three harmonicsand an estimation of the stellar temperature. High enough amplitudes can helpto identify binaries with mass ratios larger than unity, some of which mighthave compact companions.

Search for Dormant Black Holes in Ellipsoidal Variables I. Revisiting the Expected Amplitudes of the Photometric Modulation