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D. M. Gelino, T. E. Harrison, B. J. McNamara (NMSU)
Soft X-ray Transients are binary systems that are believed to consist of a black hole and a 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 any contamination from an accretion disk is minimized. By modeling the ellipsoidal variations, we can determine the orbital period and inclination of the system. The orbital inclination can then in turn be combined with the observed mass function to determine the mass of the primary object. We present preliminary results on GRS 1124-68 (GU Mus, Nova Muscae 1991). We have obtained J and K-band data on this system with the CTIO 4 meter telescope over two nights in February 2000. We have modeled these data with the WD98 light curve modeling code, and find that an orbital inclination of 53 degrees best fits both the observed J and K-band data. Using this inclination angle, we estimate the mass of the primary object in GRS 1124-68. This work was supported by an American fellowship from the American Association of University Women Education Foundation.
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