The mass ratios of SB2 binaries (Table 1) derived from the orbital solutions and CMD analysis. The diagonal line indicates the agreement of the estimates. The error bars of the photometric mass ratio account only for distance uncertainty; values of q ≲ 0.5 have particularly low credibility. For QQ Tau, an enlarged extinction assumption is required to explain the photometric data (Section 6.4.1). The right panel shows a comparison with the best-fit result from the photometric analysis of R. Liu et al. (2025).