I will give the review on the spectroscopic
methods for search for rapid oscillations in magnetic
chemically-peculiar stars and present our recent results.
For the roAp star Gamma Equulei we discovered 4 new p-modes. These frequencies, in concert with previously known, exibits well defined 62.8 $muHz general frequency spacing in the oscillation spectrum and in
echelle-diagram. We concluded, that consecutive overtones of even and odd modes are excited in Gamma Equulei. We found the increase of pulsation amplitude from the photosphere to upper layers and existence transition layer at superficial layer at the atmosphere above which the amplitude of pulsations is decreasing. I will present a discovery of a rich, sub-meter-per-second amplitude p-mode spectrum of roAp star Alp Cir that is based on the HARPS precise
radial velocity time-series. Discovered spectrum consist of 36 oscillation modes in the interval of 2173-2641 $mu$Hz and ranging in amplitude from 46 m/s to 56 cm/s. The density of frequencies and their
spacings in the spectrum indicates about first detection of excited high-degree (l>3) modes in a spectrum of a roAp star.
These discoveries established a new detection limits in the asteroseismology of roAp stars and shows the need for updates in theory and pulsation models of magnetic stars.
Dr. Mkrtichian is senior researcher at NARIT, Thailand