Main relation Φ₀ constructed by a set of fitted lines. The simulation results are shown as points of different colours for different periods, from 50 days to 4500 days (see legend at right), while a series of fitted lines in the log – log space are also plotted in the same colour. The thick blue line is the fitting result of P = 1 yr. For comparison, the dotted line shows the result of A19, calculated by Eq. (9).