Time series observations of O stars. I - IUE observations of variability in the stellar wind of Zeta Puppis

Stellar wind variability in zeta-Pup (O4 I(n)f) is described based on 31 high-resolution IUE observations secured over 5 1/2 days in 1989 April. Extensive changes are evident in the absorption regions of Si IV lambda-lambda-1393.76, 1402.77 and N IV lambda-1718.55 P Cygni profiles. Both lines exhibit similar patterns of variability, which are characterized by the development (at about -1000 km s-1), and subsequent blueward migration, of discrete absorption components. The formation of four discrete features is identified over approximately 2.2 days of intensive observations, with a recurrence time of approximately 15 hr. The time scales, velocities, and accelerations of the progressive absorption enhancements are determined. These changes are accompanied by fluctuations of up to approximately 200 km s-1 in the maximum observed blue edge velocities in saturated C IV and N V P Cygni profiles.