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D.M. Gelino, T.E. Harrison, B.J. McNamara (NMSU)
Soft X-ray Transients (SXTs) are binary systems that are believed to consist of a black hole, and a normal late type dwarf star which fills its Roche Lobe. As the distorted dwarf companion orbits the black hole, the observed flux rises and falls in a predictable manner, giving rise to "ellipsoidal variations". We observe these systems in the near infrared since the secondary star dominates the systemic luminosity and the contamination from the accretion disk is minimized. Observations in the near infrared are therefore better suited for detecting true ellipsoidal variations. By modeling these variations, we can determine the orbital period and inclination of the system. The inclination can be combined with the observed mass function to determine the mass, and therefore the nature, of the primary object. This thesis project will determine masses for five SXT primary objects. Here, we present results on GRS 1124-68 (GU Mus) and GS 2000\+25 (QZ Vul). We have obtained data on these systems with the Victor M. Blanco 4 meter telescope at Cerro Tololo, and the Apache Point Observatory 3.5 meter telescope, respectvely. We have modeled the data with the WD98 light curve modeling program. This projet is supported by an American Fellowship from the American Assocition of University Women (AAUW).