Radial velocities of RZ Cas

Using weak absorption lines we obtain an improved orbital solution for both components. In the orbital RV curve we observe a strong, asymmetric rotation effect.

For the first time we detect rapid spectroscopic multi-mode pulsations in an Algol system. Whereas the photometrically observed oscillations were dominated by monoperiodic pulsations at frequency 64.19c/d until the year 2000, we find in 2001 a multiperiodic behaviour with two dominant frequencies of f1=56.600c/d and f2=64.189c/d. Both modes show amplitude variations over the orbital phase with a minimum at orbital phases phi=0.6-0.8 and a maximum just after the primary minimum (f2) and at phi=0.25 (f1).