Peculiarities of the Stellar Population of Bars in the LMC and Other Barred Galaxies

Abstract

The age distributions in the bar and disk of the Large Magellanic Cloud are studied using data for 262 clusters with known ages, of which 89 are located in the bar. The spatial distributions for clusters in different age groups are investigated. Epochs of active star formation are determined for the bar and disk of the LMC. The ages of the stellar populations in the bar differ from that for the galaxy as a whole: in the bar, there is a deficit of intermediate-age clusters (5 × 10⁸–6 × 10⁹ yr) and an excess of young clusters with ages 3 × 10⁷–5 × 10⁸ yr. This indicates that the star formation history in the bar differs from that in regions outside the bar at the same distances from the center of the galaxy. Data on the composition of the old stellar populations in the bar and the disk of the LMC and the spatial distribution of intermediate-age clusters in the galaxy suggest that the LMC bar formed (2–6) × 10⁹ years ago. Deviation of colors of bars from the normal color sequence of galaxies on several two-color diagrams is found using multicolor surface photometry for eight barred galaxies. Using results of evolutionary synthesis modeling, I can model the abnormal colors of bars by an intermediate-age star (~ 10⁹ yr) deficiency. I find that the deficiency of an intermediate-age stellar population is a general property of bars.