PSD for five low-mass red giants (grey lines in the five panels) observed by Kepler. Panels a, b, and c: three low-mass CHeB stars KIC 5271626, KIC 6032981, and KIC 8694070 (first three rows in Table 1 and coloured stars in Fig. 2). Panels d and e: RC star KIC 1161618 and the RGB star KIC 2436824, for comparison. All five panels contain a smoothed PSD (red lines) computed with a box kernel of width 0.5 μHz in panels a, b, c, and d, and of width 0.1 μHz in panel e.