Further investigation of the high frequency optical oscillations during the flare phase of the red dwarf EV Lac

In this paper we present the results of the analysis of the U-light curve for a flare of magnitude 1.2, which was observed on September 2004, with the help of the 30-inch Cassegrain telescope of the Stephanion Observatory. The results of both, DFT-analysis and wavelet analysis, indicate that (a) Oscillations with period 1 to 1.5min, 11s, 7.5s and 5.5s appear during the pre-flare state and persist during the whole flare state, (b) From the flare maximum phase on, a progressive increase of oscillations with periods 20s up to 4.0s is markedly indicated and (c) At the end of the flare only the oscillation of the pre-flare state do remain. This result is in favour of (or does not contradict) the suggested explanation, i.e. the evolution of a fast mode magneto-acoustic wave generated at the impulsive phase of the flare and traveling through the magnetic loop.