CORRELATED VARIABILITY IN THE X-RAY AND H-ALPHA EMISSION FROM THE O4IF SUPERGIANT ZETA-PUPPIS

The Position Sensitive Proportional Counter (PSPC) onboard the ROSAT s atellite was used to monitor zeta Pup for 56651 seconds spread over 11 days in 1991 October. During the first 8 days, 592 high-resolution H alpha profiles were also obtained simultaneously. In a detailed time s eries analysis we investigate the X-ray observations and the H alpha l ine profiles for variability. We find a 1.44 c/d (cycles/day) modulati on both in the H alpha line profiles as well as in the X-ray band pass between 0.9 and 2.0 keV; the amplitude of the X-ray variability amoun ts to +/-6%. Thus, our observations provide evidence for periodic vari ations in the wind density at the base of the wind of zeta Pup.