DETECTION OF A PHOTOMETRIC PERIODICITY OF THE NOVA-LIKE VARIABLE MV LYRAE AT ACTIVE STATE

The results of the high-speed photometry obtained in July 1990 for the nova-like object MV Lyrae at maximum light (12.5 mag) are presented. Two modulations were present simultaneously, one with the mean period of 0d1379 +/- 0d0008 and another with the mean period 3d8. The light variations with the 0d1379 period had an amplitude near 4% and a coherence time of at least 36 cycles. The 3d8 beat period of the 0d1379 photometric and the 0d1336 spectroscopic period is seen in the photometry with an amplitude of 0.15 mag in unfiltered light. Quasi-periodic oscillations have been also detected in the "active state" with a period near 47 min and a mean amplitude of 2%. The general characteristics of "coherent" and quasi-periodic oscillations are reviewed and compared. Additional long series of observations are needed to confirm the reality of this type of variability.