  Our search for magnetic fields in selected OBA stars using FOcal Reducer low
dispersion Spectrographs FORS 1 and FORS 2 in spectropolarimetric mode revealed
the presence of strong line profile variations (LPV) in spectra of magnetic OBA
stars. More specifically, we detected moderate line profile variations of
selected lines on a time scale of minutes in FORS 2 spectra of the A0
supergiant HD 92207 (Hubrig et al. 2014). Recently, we investigated the
variability of line profiles of selected OBA stars with the multi-mode focal
reducer SCORPIO at the 6-meter BTA telescope. We discovered regular variations
of H and He lines in the spectra of the O-type star HD 93521 (O9.5III) with
periods ~4-5 and ~32-36 minutes. The possible origin of short time-scale
spectral variations is discussed.
