TT ARI–94: A Study of 1.6…60 Minute Variability

Abstract

We report photometric results from 44 runs at 11 observatories during the international campaign ‘TT Ari–94’. No coherent oscillations in the frequency range 10… 900 cycle d−1 are found. The highest peaks in the power spectrum cover the wide range of 28… 139 cycle d−1. Variations occur at a few preferred time-scales rather than at one cycle length, with a possible secular decrease. In the frequency range 90… 900 cycle d−1 the power spectrum obeys a power law with slope γ ranging from 0.8 to 2.6 for different runs.TT Ari is one of the brightest cataclysmic variables and remains one of the most interesting objects of this class. It exhibits a variety of phenomena observed at time-scales from seconds to months. A recent detailed photometric study of this object and a bibliographical overview may be found in Tremko et al. (1996). Tremko et al. (1992, 1993, 1994) discuss aspects of the TT Ari–88 campaign. Our campaign TT Ari–94 was unprecedented, as the observations were longitude-dispersed, from Japan through Turkmenia, to Europe and the American continent. Moreover, our optical data on October 7 partially overlap with the HST observations obtained by Home & Welsh (1995, private communication). The numerical results of observations obtained during these nights are shown in Table 1.