Superfast line profiles variability in spectra of OBA stars

We present new results of our Large Project for revealing 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 massive OBA stars are well known. Recent observations of the A0 supergiant 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 for HD 93521 (O9.5III), rho Leo (B1Iab), alpha2 CVn (A0VpSiEu), gamma UMi 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 were detected. Our spectral observations of rho Leo at the 1.25-m telescopes of Crimean Astronomical Station of the Sternberg Astronomical Institute (Russia) also lets to detection of sfLPVs in spectra of rho Leo. The presence of the short-term spectral variability in massive OBA stars, which are (at least partly) suggested to be the progenitors of Type II supernova, was not studied 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