HEAD Division Meeting 1999, April 1999
Session 15. X-Ray Binaries
Poster, Tuesday, April 13, 1999, 8:30am-6:02pm, Gold Room

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[15.22] The Infrared Ellipsoidal Variations of SXTs: Measuring Black Hole Masses

D.M. Leeber, T.E. Harrison, B.J. McNamara (NMSU)

We have obtained infrared observations of several Soft X-ray Transients (SXTs). These binary systems are believed to consist of a normal late type dwarf star that fills its Roche Lobe, and a black hole. As the distorted companion star orbits the black hole, the observed flux rises and falls in a predictable manner. By modeling the "ellipsoidal variations" of the secondary star, we can determine the orbital period and inclination of the system. Observations in the near-infrared are better suited for detecting these ellipsoidal variations because the secondary star dominates the systemic luminosity and the contamination from the accretion disk is minimized. We have begun a program on the Apache Point Observatory 3.5 m telescope to observe all of the SXT systems visible from the northern hemisphere. We report our preliminary results on QZ Vul (GS 2000 +25), V518 Per (J0422+32), and V616 Mon (A0620-00). Our data for QZ Vul's color and orbital period are consistent with published values. Modeling of the ellipsoidal variations of QZ Vul suggests an orbital inclination of 70o.


If the author provided an email address or URL for general inquiries, it is as follows:

dleeber@nmsu.edu


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