Hertzsprung-Russell diagram showing our categorised stars. The dashed line shows the zero-age main sequence, while the evolutionary tracks are shown with the dash-dotted lines. The empirical boundaries of the DSCT IS are shown with continuous blue and red lines. The ZAMS, evolutionary tracks, and IS boundaries are taken from Murphy et al. (2019). The GDOR instability region (Dupret et al. 2005) is shown with the shaded area limited by the dotted lines. All the stars in our sample including non-variable stars are shown with grey dots.