ИСТИНА

I will present the results of our observations of interacting and multi-spin (namely, with polar rings) galaxies conducted at the Russian 6-m telescope. I will focus on the oxygen abundance measurements as a diagnostic of evolution of the observed galaxies as well as of their individual star forming regions. Most galaxies from our sample demonstrate shallow or flat gradient of oxygen abundance indicating the well-mixing of ISM as result of interaction between the galaxies. Absence of the metallicity gradient in the galaxies with polar rings support the scenario of their formation in tidal accretion event and contradict the popular hypothesis of their formation as result of a cold accretion from cosmological filaments. We found few star-forming regions of peculiar oxygen abundance in the sample galaxies. In particular, significant oxygen underabundance is observed in the star-forming clump of the interacting galaxy NGC4656. We showed that it is a consequence of the recent accretion of the metal-poor gas; the recently published new HI data also support this hypothesis. I will briefly discuss the importance of the correct metallicity indicator selection on the example of this region.