The Local Galaxy Density and the Bars of Spiral Galaxies

Using a variety of parameters of local galaxy density, we have examined the effects of the environmental density on the presence of bar structures in spiral galaxies of various morphological types. For an extensive sample of nearby galaxies, listed in the Nearby Galaxies Catalog (Tully 1988a), we have found that the spirals characterized by a high local density tend to be barred if they are early-type and early- type if they are barred (at the significance level of ~3 σ), confirming some earlier suggestion of low statistical significance. This fact, which is observed substantially in low-luminosity spirals, indicates that galaxy interactions can simulate the formation of bars, primarily in early-type, low-luminosity spirals. This is in partial, qualitative agreement with the most recent relevant N-body simulations. On the other hand, no significant density segregation is observed between pure S-shaped [S(s)] spirals and spirals with inner rings [S(r)], which are often associated with bars.