Dereddened 2MASS colour–magnitude diagram of the barium stars (filled diamond symbols) and the comparison stars (filled circles). The barium star ID 410 basically coincides with its comparison star ID 409, which is why only the comparison star (the brighter one) is visible here. All other stars shown here are within a 12.5 arcmin diameter field around (l,b) = (0 °,−10 °). The solid and dashed grey lines are isochrones from Girardi et al. (2000) with the metallicities and ages as indicated in the legend. They were used to select spectroscopic targets in the bulge (see Paper I) and are truncated at the RGB tip. The RGB bump of these isochrones is at .