On the Lengths, Colors, and Ages of 18 Face‐on Bars

Abstract

Along with a brief analysis we present data obtained from BVRI and K-simages of a sample of 19 galaxies (18 barred and 1 unbarred), which willbe further explored in a future paper. We measured the lengths andcolors of the bars, created color maps, and estimated global colorgradients. Applying a method developed in a companion paper, we coulddistinguish for seven galaxies in our sample those whose bars have beenrecently formed from the ones with already evolved bars. We estimated anaverage difference in the optical colors between young and evolved barsthat may be translated to an age difference of the order of 10 Gyr,meaning that bars may be, at least in some cases, long-standingstructures. Moreover, our results show that, on average, evolved barsare longer than young bars. This seems to indicate that, during itsevolution, a bar grows longer by capturing stars from the disk, inagreement with recent numerical and analytical results. Although thestatistical significance of these results is low, and further studiesare needed to confirm them, we discuss the implications from our resultson the possibility of bars being a recurrent phenomenon. We also presentisophotal contours for all our images as well as radial profiles ofrelevant photometric and geometric parameters.