Rapid multiperiodic variability in a high-mass X-ray binary
  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 OGLE and MACHO collaborations. The light curves of two such candidates are examined for evidence of Be star behavior and for periodicity. 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; a combination of radial and non-radial pulsations is discussed. 
Daniel Fabrycky (Princeton)