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D. M. Gelino (UCSD/CASS), S. Balman, U. Kiziloglu, A. Yilmaz (Middle East Technical University), E. Kalemci (UC, Berkeley), J. A. Tomsick (UCSD/CASS)
We present optical and near infrared observations of XTE J1118+480, a black hole X-ray transient. The data were obtained with the Kitt Peak National Observatory 2.1 m telescope and the Tubitak National Observatory 1.5 m Russian-Turkish telescope, and are modeled with the WD98 light curve modeling program to find the inclination of the system, and hence, the mass of the black hole. As the distorted companion orbits the black hole, the observed flux rises and falls in a predictable manner, giving rise to ``ellipsoidal variations.'' By modeling the variations observed during X-ray quiescence, we determine the orbital inclination of the system. Both optical and infrared data are needed to fully account for any source of flux that may contaminate the ellipsoidal variations, as a constant source of light will dilute the variations giving an artificially lower inclination angle and higher black hole mass. Once the inclination is known, it is combined with the observed mass function and mass ratio (q = M_2/M_1) to find the mass of the black hole. This project is partially supported by a Center for Astrophysics and Space Sciences (CASS) Postdoctoral Fellowship.
The author(s) of this abstract have provided an email address for comments about the abstract: dgelino@ucsd.edu
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.