Nature of Purely Stellar Rings in Lenticular Galaxies

The origin of several rings in lenticular galaxies with no signs of ongoing or recent star formation (without emission lines and a signal in the ultraviolet spectral range) is investigated. Stellar population parameters—the average age and the magnesium-iron ratio—are measured; structural features are analyzed. It is concluded that the rings in all the galaxies have a different history of formation and a different nature; i.e., for only two of the four rings does the resonance origin associated with the dynamics of the central triaxial structure (bar) seem preferable.