Full 1470-day-long Kepler time series of KIC 1431599 (grey; panel a) and 100- (red and blue) and ten- (orange) day-long subsets (panels b and c). Panel d: corresponding power density spectra along with a global fit (black line) consisting of two granulation components (dashed lines), a Gaussian, and instrumental white noise fitted to the full Kepler time series (Eq. (3)). The largest amplitude peaks in the 100 d PDS are marked with vertical arrows. The corresponding sinusoidal signal is overplotted to the respective time series. The inset shows the frequency range of the oscillation power excess with individual oscillation modes marked by their spherical degree. Panel e: autocorrelation functions of the various time series.