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We report the results of 143.2 hours of time-series photometry over a 12 day period for AM CVn (= HZ 29) as part of the Whole Earth Telescope (WET) project.ˡ This star is believed to be an ultra-short period cataclysmic binary. In the temporal spectrum of the light curve we find a series of 5 harmonically related frequency mo dulations, some with sidebands with a constant frequency spacing of 20.8 μHz always on the high-frequency side. The set of harmonics has a fundamental frequency of 951 μHz. No modulation is detected at this frequency in the light curve. In addition, modulations with frequencies 972.5 and 988.9 μHz are detected with low amplitudes. The structure of the dominant 1903 Hz modulation explains part of the “phase jitter” observed earlier. The amplitude of this peak is modulated with a period of 13.32 ± 0.05 hrs.

We present our analysis of 240 hr of white-light, high-speed photometry of the dwarf nova-like helium variable PG 1346+082 (CR Boo). We identify two frequencies in the low-state power spectrum, at 679.670±0.004 μHz and 669.887±0.008 μHz. The 679.670 μHz variation is coherent over at least a 2 week time span, the first demonstration of a phase-coherent photometric variation in any dwarf nova-like interacting binary white dwarf system. The high-state power spectrum contains a complex fundamental with a frequency similar, but not identical, to the low-state spectrum, and a series of harmonics not detected in low state. We also uncover an unexpected dependence of the high-frequency powerÏs amplitude and frequency structure on overall system magnitude. We discuss these Ðndings in light of the general AM CVn system model, particularly the implications of the high-order harmonics on future studies of disk structure, mass transfer, and disk viscosity.

We report on the analysis of 154 hours of early continuous high-speed photometry on the pulsating DB white dwarf (DBV) GD 358, obtained during the Whole Earth Telescope (WET) run of 1990 May. The power spectrum of the light curve is dominated by power in the range from 1000 to 2400 μHz, with more than 180 significant peaks in the total spectrum. We identify ali of the triplet frequencies as degree l = 1, and from the details of their spacings we derive the total stellar mass as 0.61 ± 0.03 Mʘ , the mass of the outer helium envelope as 2.0 ± 1.0 x 10-6 M*, the absolute luminosity as 0.050 ± 0.012 Lʘ and the distance as 42 ± 3 pc. We find strong evidence for differential rotation in the radial direction−the outer envelope is rotating at least 1.8 times faster than the core−and we detect the presence of a weak magnetic field with a strength of 1300 ± 300 G. We also find a significant power at the sums and differences of the dominant frequencies, indi­ cating nonlinear processes are significant, but they have a richness and complexity that rules out resonant mode coupling as a major cause.