Analysis of periodic optical variability in the compact X-ray source HER X-1/HZ Herculis

Abstract

Analysis of the large pool of optical photometric data now available on the X-ray binary Her X-1/HZ Her reveals considerable variability on a time scale of hours. These flux variations are found to repeat in a highly regular fashion over the 35d X-ray ON-OFF cycle. The frequency composition and symmetry properties of this pattern suggest that the time dependence results from the uniformly changing orientation of luminous elements in this system. Subject headings: binaries - stars: individual - X-rays: sources