Activity indicators as a function of ν_max (inverted axis). LM and IM stars on the RGB are represented by grey and blue dots, respectively. LM and IM stars on the HB are represented by red and orange triangles, respectively. KIC 9267654 and KIC 9780154, which might have engulfed one or more planets since their surface rotates faster than their envelope, are shown with the magenta cross and star symbols, respectively. Vertical dotted lines indicate ν_max = 100 μHz. Continuous and dashed lines represent a fit by a power law to the RGB stars and the corresponding 2σ prediction interval around the fit, respectively.