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ИСТИНА ЦЭМИ РАН |
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Many galaxies contain kinematically decoupled structures of different types, one such a type being counter-rotating stellar discs. Recently, full-spectral fitting techniques have been exploited to extract kinematical features and stellar population properties of counter-rotating discs from integrated light spectra of galaxies. Studies of stellar counter-rotating components in disc galaxies shed light on processes of accretion and mergers which are thought to be responsible for their formation. I review recent results in this field and present our study of lenticular galaxies IC 719 and NGC 448. We observed both galaxies with the Russian 6-m telescope in the long-slit mode and used archival IFU data. We found that both galaxies have younger ages and higher metallicities of secondary counter-rotating stellar components consistent with previous studies of objects of such a type. By comparing of metallicities of counter-rotating ionized gas disc and stellar one for IC 719 we conclude that the accretion history of the external gas onto the main disc consists of two events, each with a subsequent starburst. We found that ages of the stellar secondary counter-rotating component of NGC448 are virtually indistinguishable from the main disc component and conclude that it is formed due to satellite merging event.