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We present the analysis of six nights of spectroscopic monitoring of twoyoung and fast rotating late-type stars, namely the dMe star HK Aqr and thedG/dK star PZ Tel. On both stars we detect absorption features reminiscent ofsignatures of co-rotating cool clouds or prominences visible in H$\alpha$.Several prominences on HK Aqr show periodic variability in the prominencetracks which follow a sinusoidal motion (indication of prominenceoscillations). On PZ Tel we could not find any periodic variability in theprominence tracks. By fitting sinusoidal functions to the prominence tracks wederive amplitudes and periods which are similar to those of large amplitudeoscillations seen in solar prominences. In one specific event we also derive aperiodic variation of the prominence track in the H$\beta$ spectral line whichshows an anti-phase variation with the one derived for the H$\alpha$ spectralline. Using these parameters and estimated mass density of a prominence on HKAqr we derive a minimum magnetic field strength of $\sim$2G. The relatively lowstrength of the magnetic field is explained by the large height of this stellarprominence ($\ge$ 0.67 stellar radii above the surface).

Indications of stellar prominence oscillations on fast rotating stars: the cases of HK Aqr and PZ Tel