The greater a star's metallicity, the better its chances to have planets.
If the metallicity is too low, there is not enough material to build Earth-like planets.
The process can make planets with enriched metallicities as seen in our own solar system.
For example, the radial galactic metallicity gradient determines isotope concentrations, silica and magnesium concentrations, etc., all of which are important for forming habitable planetary systems.
The bar will hence be able to relocate stars, and stars with low or high metallicity could be found far away from their original orbits.
For example, until sufficient metallicity has developed by the stellar burning of light elements, terrestrial type planets will not form.
This occurs more rapidly in stars that are more massive and lower in metallicity.
Thus, high metallicity stars could be found in all parts of a barred galaxy.
