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Astron. Astrophys. 321, 145-150 (1997)

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10. Conclusion

We detect here a significant increase of the amplitude of [FORMULA], one of the non-radial modes in 16 Lac. For the first time since precise photometry is being achieved, this amplitude is greater than that of [FORMULA], which underwent a slow amplitude decrease in the past decades and still is at a low level. [FORMULA] and [FORMULA] are not in a good agreement with their previous ephemeris: the value of the periods could have changed by a small but significant amount or/and their maximum light epoch has to be shifted: the ephemeris calculated from the 1950's to 1984 cannot represent our 1987-1992 [FORMULA] and [FORMULA] data with the same precision as before.

We confirm here that [FORMULA] is probably of a different nature from [FORMULA] and [FORMULA], and likely a radial mode with, in our 1987-1992 data, a possible dissymetric light curve.

All other previous low amplitude periods appear as non-existent or marginal in our observations. The period 0.139 d belongs to the principal comparison star, with a very low (under 2 mmag) amplitude.

The amplitudes of [FORMULA] are still in phase with the orbital period, or in phase with the rotation as they are very probably synchronized, but further studies have to confirm this behavior, as it is based until now on rather low correlations.

It is shown here that the total pulsational energy available in the visible part of the spectrum does vary: at least in the 0.15 - 0.20 d range, there is no redistribution of the pulsation energy between the different modes.

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© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998