Plots of the period vs. log T for primary stars (1), secondary stars (2), and the binary systems (3) of the W-subtype (‘+’ symbols) and A-subtype (‘×’ symbols) from sub-SRASS. (4): Plot of log T vs. log L_X. The dashed lines are at P = 0.44 days. The light blue points and gray line in the background of panel (4) are the Spec-EWX sample points and its fitting line from Fig. 5 (1 and 2).