High-speed photometry of Z Camelopardalis

High-speed photometry of Z Cam shows that its light curve bears a strong resemblance to the light curves of U Gem and VV Pup. Strong flickering is always present in Z Cam and has an amplitude correlated with the position of Z Cam in its eruption light cycle. Z Cam does not show eclipses. Low-amplitude sinusoidal periodicities have been found in the light curve during eruptions with periods between 16 and 19 seconds. A model of Z Cam is constructed whose major new feature is a bright spot on the disk of gas around the white dwarf. The bright spot contributes at least 20 percent of the total light of Z Cam during minima, and is the source of the flickering. The periodicities are interpreted as nonradial pulsations of the white dwarf. On the basis of the pulsations, it is shown that the white dwarf must be the seat of the eruptions. During the eruption the disk of gas increases in radius. Subject headings: binaries - stars, individual - U Geminorum stars