Kiel diagrams showing the atmospheric parameters of the observed stars as determined via the spectroscopic best-fit with model spectra representing MS and BHB stars (top and bottom panels, respectively). Top panel: evolutionary tracks for rotating MS stars are plotted in black (Ekström et al. 2012). The initial masses of each model are noted below the zero-age MS (thick solid curve), while the stellar ages for selected evolutionary points along the tracks are given in mega years. Bottom panel: the horizontal branch is represented by the gray-shaded area, and the evolutionary tracks for post-horizontal branch stars of different masses are drawn as solid curves (Dorman 1992).