Large-scale mixing in Barred galaxies

Numerical simulations including star formation and chemical enrichment have been carried out for bar formation in both dynamically unstable galactic disks and tidally perturbed disk galaxies. Spontaneous bars and tidally-triggered bars show the qualitatively same behavior in the change of chemical abundance gradient, defying the possibility of descriminating between the two types of bars by abundance study. Both models can explain the observed correlation between the spatial distribution of star forming regions in a barred galaxy and its abundance gradient slope as a manifestation of the chronological sequence of the infall of metal-poor interstellar gas.