Plots of the period vs. stellar mass for primary (1) and secondary (2) from sub-SRASS, and the mass of primary (3) and secondary (4) vs. log L_X. The black dashed line in panels (1) and (2) is at 0.44 days. The small black points with dashed line in panels (3) and (4) indicate the X-ray luminosity of the main sequence star at saturation in the mass range (0.22–1.7 M_⊙). In panel (1), the blue contours contain the data points from the 10 000 simulated samples (see text) with masses corresponding to the spectral temperatures from Spec-EWX (extra adding 0−200 K random errors of uniform distribution for each object) against the period, while the gray line and light blue dashed lines are the best-fit relation of these points with periods of ≤0.44 days and its 95% uncertainty range. The blue and red histograms (with 0.02-day steps) with axis on the right represent the period distributions of the primary stars with masses less than 1.1 M_⊙ and greater than 1.1 M_⊙, respectively (the average value of 10 000 simulations).