SHORT-TERM LINE-PROFILE VARIATIONS AND EPISODIC MASS-LOSS IN THE BE STAR ZETA-OPHIUCHI

High-resolution spectra have been obtained for the rapidly rotating ea rly-type star zeta Oph at three epochs in 1990, covering its recent em ission episode. We found that at least two nonradial pulsation modes h ave been excited; an l = - m = 4 mode with a period of 3.33 h and an l = - m = 7 mode with period 2.43 h, if they are assumed to be sectoral modes. These modes are identical to those found in our previous obser vations from 1987 to 1989. Models other than nonradial pulsation to ex plain the origin of the line-profile variations are critically discuss ed. No significant change of the rotational velocity has been detected throughout our observations. The time scale of the acceleration of th e equatorial region by the observed nonradial pulsations is estimated and is shown to correspond to the Be-type quasi-periodic mass loss cyc le in the star. A correlation between amplitudes of line-profile varia tions and mass loss indication might be seen in this star. The amplitu de of line-profile variations are larger around the emission episode, and decreased at the end of the emission episode. This suggests a conn ection between line-profile variations and episodic mass loss in this star.