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D.C. Fabrycky (Princeton University)
Positions of High-Mass X-ray Binaries are often known precisely enough to unambiguously identify the optical component, and a number of those stars are monitored by the Optical Gravitational Lensing Experiment (OGLE) and MACHO collaborations. The light curves of two such candidates are examined for evidence of Be star behavior and for periodicity. These stars are likely companions to long-period X-ray pulsars in the Small Magellanic Cloud. One of the stars exhibits two periods of 6.833 and 15.586 hours, much shorter and more stable than periods of Be/X-Ray Binaries that are attributed to the Be star’s disk, but consistent with short-term Be variability attributed to pulsations. The multiperiodicity is quantified with Fourier techniques and examined for phase stability. The phase of both variations has wandered by more than a cycle during the 11 years of optical monitoring. A combination of radial and non-radial pulsations is a possible physical mechanism. Support was provided by NSF grant AST-0204908 and NASA grant NAG5-12212 to Bohdan Paczynski.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.