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Paper: Fast Microvariations in Spectra of Early-Type Stars
Volume: 494, Physics and Evolution of Magnetic and Related Stars
Page: 239
Authors: Kholtygin, A. F.; Hubrig, S.; Schöller, M.
Abstract: Our recent search for the presence of a magnetic field in the spectra of selected OBA stars using the FOcal Reducer and low dispersion Spectrographs FORS1 and FORS2 in the spectropolarimetric mode revealed strong line profile variations (LPV) in the spectra of magnetic OBA stars. The obtained low-resolution FORS2 polarimetric spectra allowed us to detect a significant LPV of several hydrogen and helium lines on a rather short time scale. We also detect moderate line profile variations of diverse lines on a time-scale of minutes or maybe even a fraction of a minute in the FORS2 spectra of the A0 supergiant HD 92207. The presence of short-term spectral variability in blue supergiants, which are proposed to be the Type II supernova progenitors, has not been a subject of systematic studies before and can be critical for the current theoretical understanding of their physics. The short-term periodicity was not known before for non-radially pulsating supergiants, and its confirmation is of great importance for modeling the stellar evolution.
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