SIMBAD references

The High-Speed Photometer (HSP) was one of the four axial instruments on the Hubble Space Telescope (HST) from April, 1990 to December, 1993. We used this instrument to observe the X-ray binary systems HD 153919, Vela XR-1 and Cyg XR-1 both photometrically and polarimetrically in the UV. The photometric and polarimetric light curves of each target have been constructed by measuring the flux and linear polarization in several wavelength bands, at several different phases within one binary orbit.

The results obtained from the UV polarimetric observations provide strong evidence for Rayleigh (recombined material) scattering from gas streams and stellar wind in these systems. The amplitude of polarimetric variability increases significantly in the UV, for all three systems. The UV polarimetric light curves obtained for Vela XR-1 and HD 153919 show an added component of linear polarization present at first quadrature, inconsistent with the standards model of Brown et al. (1978). However, the UV polarimetric light curves obtained for Cyg XR-1 are well-represented by the standard model. There was also evidence for changes in the circumbinary scattering structure from one orbit to the next, in Cyg XR-1 and Vela XR-1. In addition to these results, we derived estimates for the orbital inclination, location of the scattering structure relative to the line of centers, and orientation of the orbital angular momentum for the system (and associated confidence intervals for each parameter). These results were compared to previously published ground based observations.