HII versus HI in the 'green valley' galaxies: direct comparison

We study the morphology and kinematics of the ionization state of the gas in four 'green valley' early-type galaxies at different stages of their transition from a 'blue cloud' of star-forming galaxies to the sequence of passive evolution. The previous HI mapping of the considered sample reveals a spatial offset between the cold gas reservoirs and stellar discs depending on the post-starburst age. Consideration of the ionized-gas properties is essential to understand the role of various feedback processes in star formation quenching. We performed long-slit and 3D optical spectroscopic observations at the 6-m Russian telescope and compared the gas and stellar kinematics. Spatial distribution of the ionized gas is in agreement with HI maps; however, the one-order higher angular resolution in the HII velocity fields allows us to study non-circular gas motions in detail, like the AGN-driven outflow in the nucleus of J1117+51. The most intriguing result is the global HI+HII gas counter-rotation relative to the stellar disc in J1237+39. Therefore, in this case all the observed gas in the 'green valley' galaxy was captured from the environment via accretion or minor merging.