A Search for Periodic and Quasi-periodic Photometric Behavior in the Cataclysmic Variable TT ARIETIS
Observations of TT Ari obtained at 11 observatories (campaign TT Ari-94) during 258 hr were carried out to study optical variability on timescales from minutes to weeks. The best-fit primary photometric period determined from 16 nights of data obtained at the Dushak-Eregdag station of the Odessa State University is P=0.133160°+/-0.000004° with a mean amplitude of 0.0513+/-0.0008 mag. This new primary photometric period is larger than that obtained during the TT Ari-88 campaign and is well outside the range of estimates published since 1961. Contrary to previous findings, the ``5-7 hr'' secondary photometric period is not seen. Our observations do show evidence for periods of 2.916° and 0.3040° with amplitudes of 43 and 25 mmag, respectively. The beat period between the spectroscopic and photometric periods is not seen. No coherent oscillations in the range f=10-2500 cycles day^-1 are found. The highest peaks in the power spectrum cover the wide range of 24-139 cycles day^-1. In the mean periodogram, the highest peak corresponds to 21 and 30 minutes for the largest sets of observations, i.e., those obtained at Odessa and Krakow Universities, respectively. In the instrumental B system, variations with an amplitude exceeding 0.011 mag occur 8 times (from 33 runs) at 24 minutes. We conclude that quasi-periodic variations occur at a few preferred timescales rather than at a relatively stable period with a secular decrease. In the frequency range 90-900 cycles day^-1, the power spectrum obeys a power law with a slope ranging from gamma=1.3 to 2.6 for different runs.