Gaseous-phase metallicities and stellar populations in the centres of   barred galaxies
  Numerical simulations predict that bars represent a very important agent for triggering gas inflows, which in turn could lead to central star formation. Bars thus are thought to contribute to the formation of the bulge.This changes both, the gaseous-phase and stellar-phase metallicities in the centres of galaxies. With the aim of quantifying the importance of this process we present a comparative study of the gaseous-phase and stellar-phase metallicities in the centres of members of a sample of barred and unbarred galaxies from SDSS. We do not find a significant difference in the metallicity (neither gaseous nor stellar) of barred and unbarred galaxies, but we find different trends in the metallicities of early- and late- type galaxies, with larger differences in the metallicity in the early-type subsample. Our results contradict some previous research in this field, but we find a possible origin of the discrepancies between previous works and our results. 
Ra\'ul Cacho, Patricia S\'anchez-Bl\'azquez, Javier Gorgas and Isabel   P\'erez
astro-ph.GA