We present results of our large project for searching the superfast line profile variations (sfLPVs) in spectra of bright OBA stars. The regular variations of the line profiles with periods ranging from a few hours to days in spectra of all OBA stars are well known. Recent observations of the A0 super giant HD 92207 using FORS 2 spectrograph in spectropolarimetric mode mounted on the 8-m VLT telescope showed moderate line profile variations of various lines on a time-scale of minutes. Such short time-scale LPVs were also detected in our spectral time series of HD 93521 (O9.5III), rho Leo (B1Iab), and alpha2 CVn (A0VpSiEu) and other stars obtained with the multi-mode focal reducer SCORPIO at the 6-meter telescope (Northern Caucasus, Russia). Both regular LPVs with periods from 1 to 90 minutes and non-regular LPVs with amplitudes of 1-2% of the continuum level are detected. Our spectral observations of rho Leo at the 1.25-m telescopes of Crimean Astronomical Station of the Sternberg Astronomical Institute of the Moscow State University (Russia) also revealed the sfLPVs in spectra rho Leo. The presence of the short-term spectral variability in massive OBA stars, which are suggested to be the progenitors of Type II supernova, was not studied systematically in the past and can be crucial for the current theoretical understanding of the supernova physics and for modeling the stellar evolution. We plan to increase the number of telescopes used for observations of OBA stars with ultra-high temporal resolution.

{"references": ["Kholtygin, A. F., et al. 2017, ASPC, 510, 299", "Kholtygin, A. F., et al. 2018, Astrophysical Bulletin, 73, 471", "Kholtygin, A. F., et al. 2020, Astronomy Letters, 46, 168"]}