Observations of rapid blue variables - XVIII. Rapid oscillations in dwarf novae

Abstract

Observations of rapid oscillations in brightness during outbursts of the dwarf novae CN Ori, AH Her, Z Cha, VW Hyi and V436 Cen are described. Correlations of oscillation period with orbital phase are found. The oscillations show a large phase shift during eclipses of Z Cha. A 413-s modulation of the 30-s oscillations in VW Hyi has been found. Evidence is given for the existence of a period–luminosity relationship. These observations put new restrictions on possible models for the rapid oscillations in dwarf novae.