SIMBAD references

We present a series of high resolution spectra of the HeI λ667.8nm line of η Cen obtained in 1990 and 1992. Features < 1% of the continuum were detected moving from blue to red through the line profiles. These variations are examined in terms of nonradial oscillations. The acceleration and average spacing of the features are consistent with an l=|m|=14±4 sectorial mode or with an l≃7, m≃6 tesseral mode. The azimuthal degree did not change during the time span of the observations which sets a lower limit of about two years for the stability of stellar surface pattern.