ИСТИНА

Despite the general view that lenticular galaxies are `red and dead', they often possess large amount of cold gas, and roughly the half of gas-rich S0 galaxies reveal some level of current star formation organized in ring-like structures. We have undertaken a spectral study of a sample of starforming (UV-bright) rings in nearby S0 galaxies to clarify the origin of the gas and the regimes of star formation in the rings. We have found frequent decoupling between the gas and star kinematics implying the gas external origin. Also we have measured emission-line fluxes in the rings for all strong emission lines in the optical spectral range, trying to check the mechanism of gas ionization by plotting the emission-line flux ratios onto the diagnostic BPT-diagrams. Most emission-line rings confirm the gas excitation by young stars, and we have succeeded to estimate the gas oxygen abundance in these rings through the `strong-line method'. To our surprise, the gas oxygen abundance in the rings is always close to solar one, despite the subsolar metallicity of underlying old stellar populations and independently on the ring radius.