E. Kambe et al., SHORT-TERM LINE-PROFILE VARIATIONS AND EPISODIC MASS-LOSS IN THE BE STAR ZETA-OPHIUCHI, Astronomy and astrophysics, 273(2), 1993, pp. 435-450
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.