2006PASP..118..809N

Time-resolved Hα spectra of the Algol-type binary RZ Cas are obtained in the primary minimum. The observed spectral feature at the mid-primary minimum does not coincide with that of the secondary component. The observed equivalent widths are found to be larger than the modeled one, and the distribution of the differential equivalent widths of the Hα line is found to be asymmetric relative to the mid-primary eclipse. These features indicate that the temporal appearance of a ``flat bottom'' around the mid-primary minimum is caused by the superposition of the light variations due to eclipse and those due to the pulsation of the primary component, and also suggest the presence of circumstellar matter in the system.